Cattle Practice 9.1

BCVA 2001 49 CATTLE PRACTICE VOL 9 PART 1 cow was recumbent. Milk samples were plated onto sheep blood and blood aesculin (Edward's) media. Streptococcus uberis was identified by aesculin splitting on Edward's media. Where the original clinical case was caused by S. uberis, farmers were asked to take post-treatment samples 7, 14 and 21 days after the last treatment. Samples were plated up and identified as for the initial clinical samples on the day of diagnosis. RESULTS AND DISCUSSION One thousand three hundred and sixty two milk samples from clinical cases of mastitis, from 1313 cows on 75 dairy farms were submitted for bacteriological examination. Figure 1 shows the percentage of different bacteria isolated. The most prevalent bacteria isolated were S. uberis (27%), coliforms (23%), coagulase negative Staphylococcus spp. (12%) and various other bacterial species (13%). There was also a high percentage of no growths (17%), possibly due to rapid elimination of the pathogen by the cow, continued activity of natural inhibitors in the milk between sampling and culturing, or the presence of inhibitory substances. The presence of antibiotics is unlikely in the light of good farmer compliance. Study of Bacteria Causing Clinical Mastitis and Pilot Investigation of the Response to Treatment of Cases Caused by Streptococcus uberis (Reproduced from Proceedings of the International Dairy Federation Symposium on Immunology of the Ruminant Mammary Gland, Stresa, Italy, 11-14 June 2000) Milne M.H1., Barrett D.C1., Fitzpatrick J.L1., Biggs A.M2. 1Division of Farm Animal Medicine and Production, Department of Veterinary Clinical Studies, University of Glasgow Veterinary School, Bearsden Road, Glasgow, G61 1QH. 2Vale Veterinary Centre, The Laurels, Station Road, Tiverton, Devon, EX16 4LF. INTRODUCTION Streptococcus uberis is an increasingly common cause of clinical mastitis (Leigh 1999). It is also recognised as being particularly difficult to treat and thus frequently causes persistent infections (Thomas et al 1995). The primary aim of this study was to identify the bacteria responsible for clinical mastitis on dairy farms in Devon, serviced by the Vale Veterinary Centre. As a secondary aim, the response of clinical mastitis caused by S. uberis to treatment was monitored. MATERIALS AND METHODS Farmers were requested to take a pre-treatment milk sample, using an aseptic technique, from each case of clinical mastitis and to record details of the milk yield, udder texture, appearance of the milk and demeanour of the cow. Farmers were asked to record milk yield as normal if it was unchanged, low if it reduced by ≥5% and very low if it reduced by ≥10%, compared to the pre-infection yield. Udder texture was judged by palpation of the udder and classified as normal, swollen or hard. The appearance of the milk was classified as having few clots, many clots, or of watery consistency. The demeanour of the cows was assessed as normal if the cow was unchanged, sick if the cow was inappetant and very sick if the ABSTRACT The prevalence of bacteria causing clinical mastitis was determined on farms in Devon, England. The farmers recorded the clinical signs in cattle with clinical mastitis and the appearance of the mammary secretions prior to treatment. In mastitis cases caused by Streptococcus uberis, the response to conventional treatment was monitored by routine bacteriological culture of milk samples on days 7, 14 and 21 post-treatment. Despite conventional treatment, 43% of S. uberis cases were considered to have remained persistently infected, as assessed by at least one positive isolation at one of the three time points post-treatment. Fifteen percent of these were detected at day 14 or 21 but not on day 7. The results of the post-treatment sampling show that repeated sampling is needed to monitor if S. uberis infection has been cleared effectively from the mammary gland.

CATTLE PRACTICE Table 1 shows data collected by farmer observation. The numbers in this table do not always add up to 100%, as the farmers did not pass judgement on all the signs in each category, or occasionally indicated the presence of more than one sign in a particular category. The clinical appearance of cases infected with different classes of organisms was seen to differ. In general, the clinical signs were least severe with Staph. aureus infections, most severe with coliform infections and intermediate with Staphylococcus spp. infections. The severity of signs in cases with E. coli mastitis may be due to the production of endotoxins by this Gram negative organism and the induction of a marked inflammatory reaction. Cases caused by E. coli had the greatest proportion of cases presenting with watery milk, hard udders, low or very low milk yields and sick, or very sick, cows. The clinical effects of Staph. aureus infections may be less obvious as they may have existed in a subclinical state for some time prior to the clinical episode, or they may inherently produce less dramatic signs. Coagulase negative Staphylococcus spp. tended to BCVA 2001 VOL 9 PART 1 induce intermediate changes in the milk and udder and most cows appeared normal in demeanour. Persistent infections with S. uberis were presumed when any uncontaminated post-treatment milk sample yielded three or more S. uberis colonies. In total, 368 cases of S. uberis mastitis were identified, of these 180 were reassessed and re-sampled posttreatment. Based on the criteria of one positive isolate at any one of the three time points post-treatment, 43% (78/180) of S. uberis infections were shown to persist. Thirty seven percent (66/180) of cases proved to be persistent infections when examined on day 7 post-treatment, a further 4% (8/180) on day 14 and an additional 2% (4/180) on day 21 (Figure 2). This highlights the fact that in some cases of S. uberis mastitis, bacteria were not isolated one week after conventional treatment but were isolated when samples were checked again two and three weeks after treatment. Thus, a single post-treatment sample would have underestimated the prevalence of persistent infections caused by S. uberis. 50 Figure 1. Bacterial isolates from milk samples from 1362 clinical cases of mastitis. Staphylococcus aureus 3% Streptococcus dysgalactiae 5% Miscellaneous bacteria 13% Table 1. Percentage of 313 cases of clinical mastitis showing local mammary gland and systemic signs as assessed by the farmer. Bacteria Milk Appearance Udder Texture Milk Yield Demeanour of Cows Few clots Many clots Watery Normal Swollen Hard Normal Low Very Low Normal Sick Very Sick Streptococcus uberis 41 47 5 31 54 10 55 28 6 84 8 1 Coliforms 26 31 33 13 56 13 13 62 23 51 31 13 Staphylococcus aureus 37 63 0 63 37 0 63 25 0 100 0 0 Streptococcus dysgalactiae 42 50 4 8 79 8 25 58 4 92 4 0 Coagulase negative Staphylococcus spp. 52 39 4 45 38 13 57 34 2 95 2 0 No growth 48 28 8 46 33 6 56 23 3 77 8 0

CATTLE PRACTICE CONCLUSIONS • The main organisms identified from clinical cases of mastitis were S. uberis, coliforms and coagulase negative Staphylococcus spp. • Forty three percent (78/180) of S. uberis infections were shown to be persistent after conventional treatment. • Fifteen percent (12/78) of the persistent S. uberis infections detected would have been missed if only a day 7 post-treatment sample had been cultured, as these were isolated only from samples submitted either 14 or 21 days after treatment. FUTURE It is proposed to use retrospective strain typing to distinguish true persistent infections from reinfections. It would be expected that re-infections BCVA 2001 VOL 9 PART 1 would have different strain types to the initial infection due to the large strain diversity of S. uberis (Jayarao et al 1991). As an adjunct to this investigation, a comparative field trial has just started using extended (pulse) treatment using two different intramammary preparations for persistent S. uberis infections. ACKNOWLEDGEMENTS The authors wish to acknowledge Pfizer Animal Health, the RCVS Trust Fund and the University of Glasgow Veterinary School for financial support, and the organisers of the International Dairy Federation Symposium on Immunology of the Ruminant Mammary Gland for allowing us to reproduce this poster here. We also wish to thank Anthea Ellicott and Bruce Richards for their technical assistance and the dairy farmers who contributed to this study for their continued co-operation. REFERENCES Leigh J. A. (1999) Streptococcus uberis: a permanent barrier to the control of bovine mastitis? The Vet. J. 157: 225-238 Thomas L. H., Haider W., Finch J. M. (1995) Cows with chronic infections of the mammary gland with Streptococcus uberis mount little inflammatory response and have an intact humoral immune response. Proceedings of the Third IDF International Mastitis Seminar Tel-Aviv, Israel Jayarao B.M., Oliver S.P., Tagg J.R., Matthews K.R. (1991) Genotype and phenotype analysis of Streptococcus uberis isolates from bovine mammary secretions. Epidemiol. Infect. 107: 543- 555 51 Figure 2. Percentage of cases from which Streptococcus uberis was isolated from posttreatment samples. 0 10 20 30 40 50 % 7 days 14 days 21 days first detected total re-isolates

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BCVA 2001 53 CATTLE PRACTICE VOL 9 PART 1 the first three week period or 600 g/d in the second 4 week period. Hoof lipids were analysed from slivers from 4 cows from S and 4 from C approximately 8 weeks after supplementation. The fatty acid profile of the total lipids extracted from the hoof slivers was determined using gas-liquid chromatography. Blood samples taken whilst the animals were on the experimental diets were fractionated into different lipid fractions and also analysed using gas-liquid chromatography. Significant differences were seen in the blood lipid profiles of animals in the supplemented and control diets. Supplementation with fish oil significantly changed the blood lipid profile and gave significant increases in the levels of polyunsaturated fatty acids (p=0.041) in the hoof lipids of S. Saturated fats were decreased and long chain and n-3 fats were increased but these differences were not significant. In terms of specific fatty acids there were significantly more C17:1 (n-7) and significantly less C18:2 (n-6) in S. The study demonstrates that the claw horn lipid profile of dairy cattle can be altered by manipulation of dietary fat intake. It remains to be demonstrated if this will also reduce lameness due to claw horn disruption. Effects of Dietary Fish Oil Supplementation on the Hoof Lipid Fatty Acid Profiles of Dairy Cattle Offer J.E1., Offer N.W2., Logue D1. 1Dairy Health Unit, SAC Veterinary Science Division, Auchicruive, Ayr, Scotland, KA6 5AE. 2Food and Farming Systems Division, SAC Auchincruive , Ayr, Scotland, KA6 5AW. The profiles of fatty acids found in hoof lipids from lame cattle are quite different to those from sound animals. Although the underlying mechanism for these changes this remains unclear there is the possibility of influencing levels of lameness by manipulating hoof lipid composition. In many species this could easily be achieved by dietary means, however in the ruminant, fatty acids are biohydrogenated by rumen micro-organisms, thereby changing the nature and the characteristics of the fatty acids absorbed from the gut. Nevertheless, it has been shown that dietary supplementation with fish oil can change the nature of circulating milk and tissue lipids. In the present study the hoof lipids from animals that had been either offered dietary fish oil supplements (S) or not (C) were compared. Two groups of 28 mid to late lactation mature Holstein Friesian and Ayrshire dairy cows were included in a continuous design experiment. All cows received ad libitum a complete diet of grass silage (757), (kg/tonne FW) Supergrains (149), barley (75) and soya (19) plus 1 kg/day dairy concentrate at milking. Animals in group C also received 2.76 kg/day molassed sugar beet pulp (MSBP) whilst animals in S received 2.76kg/d MSBP and 300 g/d fish oil for

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BCVA 2001 55 CATTLE PRACTICE VOL 9 PART 1 that had been owned by the farmers in recent years. Culling reasons were classified into 7 broad categories (for details see Table 1). Information was also gathered on general health and husbandry factors relating to the bulls. From the total of 498 questionnaires sent, 287 were returned giving a response rate of 58%. From these 287 there was complete data on a total of 606 bulls which had been culled following use. The breeds of bull included in the survey are summarised in Table 2. The commonest breeds of bulls being used were Charolais, Simmental and Limousin. The average age at culling was 5.8 years. The reasons for culling are summarised in Table 3. The commonest reason for culling was due to musculoskeletal problems. This is the first survey of this kind to be reported in the UK and the results suggest that most beef stock bulls are culled before six years of age. Since young bulls are not usually used until they are at least 18 months old then this suggests that most purchased bulls will only work for 4 years in a beef herd. A Survey of the Longevity and Reasons for Culling in UK Beef Stock Bulls Penny C.D., Faulkner G., Boreland J., Doyle B., Wilson A., Gibson D., Ballard D., Department of Veterinary Clinical Studies, Royal(Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian, EH25 9RG Beef stock bulls represent a considerable investment for commercial suckled calf producers. An estimate of the working life of stock bulls is important when working out farm economics and considering costings of alternative breeding options such as artificial insemination(AI). In the United Kingdom (UK) at present the cull value of an adult bull is negligible due to the over thirty month scheme (OTMS) payment limits. This means the annual depreciation costs on an expensive bull are considerable unless it has a long working life. There is little information in the literature regarding the longevity of stock bulls and the reasons they are finally culled. A survey was therefore carried out to try and establish the average working life of beef stock bulls in the UK and what the reasons for culling were. A total of 498 UK beef farmers were surveyed by postal questionnaire as part of a final year veterinary student undergraduate project. The questionnaires were designed to get retrospective information on the longevity and reasons for culling in beef stock bulls Table 1. Description of culling reasons used to categorise bulls. Culling Reason Details Musculoskeletal problem Included culling due to foot and leg lameness, back problems, fractured limbs Management decision Included reasons such as poor offspring, risk of inbreeding daughters and change of farm breeding policy Old age Bulls culled due to age at end of working life with no problem specified Infertility Bulls culled due to fertility problems including lack of libido Disease Bulls culled due to miscellaneous infectious diseases, abdominal catastrophe or sudden death Penile problems Bulls culled due to spiral deviation, penile rupture/haematoma Poor temperament Bulls specifically culled due to poor temperament in themselves and /or offspring Table 2. Breeds of 606 bulls represented in survey. Breed Number of Bulls(%) Charolais 224 (37%) Limousin 126 (20.8%) Simmental 120 (19.8%) Aberdeen Angus 71 (11.7%) Blonde Aquitaine 19 (3.1%) Hereford 14 (2.3%) Belgian Blue 12 (2%) Galloway 8 (1.3%) Shorthorn 5 (0.8%) Miscellaneous 7 (1.2%) Table 3. Summary of culling reasons in 606 bulls. Reason for culling Number of bulls (%) Musculoskeletal problem 188 (31%) Management decision 174 (28.7%) Old age 91 (15%) Infertility 58 (9.6%) Disease 42 (7%) Penile problem 27 (4.5%) Poor temperament 26 (4.3%)

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BCVA 2001 57 CATTLE PRACTICE VOL 9 PART 1 differences were demonstrated between strains from Dumfries and Galloway and those from elsewhere apart from all isolates from one farm which were uniquely found to contain an additional plasmid. Work carried out at the Institute for Animal Health at Compton using in vitro epithelial cell culture assays showed no differences in the adhesive and invasive potential of strains from Dumfries and Galloway 1999 and control strains. There is therefore no evidence to support the hypothesis that the increased incidence is the result of the emergence of a more virulent clone. Further investigations are on-going. ACKNOWLEDGEMENTS The authors thank Dr. P. Watson of the Institute for Animal Health at Compton for in vitro testing of adhesive and invasive abilities of outbreak strains. SAC VSD receives financial support from SERAD. Salmonella Dublin in Dumfries and Galloway Seaton A1., Mather H2., Brown D. J2 1SACVSD Dumfries, St. Mary's Industrial Estate, Dumfries, DG1 1DX. 2Scottish Salmonella Reference Laboratory, Stobhill Hospital, 133 Balornock Road, Glasgow, G21 3UW. Salmonella Dublin is a host adapted serotype of Salmonella enterica subsp enterica. Levels of diagnosed infection in cattle in the UK have remained low since the early 1970s. However since Spring 1999 an increased number of Dublin infections have been diagnosed at Dumfries DSC. The increase has been peculiar to the South West of Scotland with 90% of outbreaks being reported through Dumfries or the neighbouring centre at Ayr. The peak of disease in both 1999 and 2000 occurred in the late Summer and Autumn. The pattern of clinical signs seen in the last two years is similar to that seen previously with abortion and enteritis in adults and enteritis pyrexia and pneumonia in preruminant calves predominating. The Scottish Salmonella Reference Laboratory at Stobhill carried out serological confirmation, pulsed-field gel electrophoresis and plasmid screening. No significant

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BCVA 2001 59 CATTLE PRACTICE VOL 9 PART 1 routine visits are usually scheduled every seven or 14 days and involve tasks such as postpartum examinations, pregnancy diagnosis (PD), examination of cows not observed in oestrus and the examination and treatment of cows with specific pathology of the reproductive tract. In many instances the veterinarian simply examines those cows presented by the farmer and reports his findings back to the farmer. However, a minority of veterinarians also maintain detailed herd records for their clients, and are therefore able to select cows for examination and monitor trends in herd fertility in their client's herds. Those farmers that don't employ their veterinary surgeon to maintain their herd records either maintain paper based or computerised systems themselves on the farm, or use one of the commercially available central recording systems such as the National Milk Records (NMR). THE UK NATIONAL HERD The total UK national herd consisted of approximately 11.5 million cattle in 1999, with the breeding herd being made up of 2.44 million dairy cows and 1.92 million beef suckler cows. A detailed breakdown of the herd size is shown in Table 1. Cattle Fertility Management in the UK Barrett D.C., Division of Farm Animal Medicine and Production, Department of Veterinary Clinical Studies, University of Glasgow Veterinary School, Bearsden Road, Bearsden, Glasgow, G61 1QH. INTRODUCTION This paper originally written for presentation to the Portuguese Buiatrics Association describes in general terms the UK national herd, and as far as available data allow, determines the trends in cattle fertility over recent years. It then discusses briefly the possible reasons for these trends and the ways in which the veterinary profession is working, and will continue to work, with the cattle industry to try to optimise fertility within the constraints of current production systems. Cattle fertility management in the UK is largely in the hands of herd owners and stockmen with variable veterinary input. Where there is direct veterinary involvement in the management of herd fertility this is usually provided by the local private practice veterinarian. The level of such involvement varies greatly from practice to practice and farm to farm. In many instances the veterinarian only becomes involved if the farmer requires a specific veterinary task undertaken or if (s)he considers that a problem has arisen which requires veterinary intervention. On the other hand some specialist practitioners are involved in the provision of regular and routine veterinary herd health visits where fertility management is usually the major objective. These ABSTRACT Cattle fertility management in the UK involves variable levels of veterinary intervention, from minimal involvement when veterinary attention is sought for individual problem cows only, to routine herd health visits when veterinarians are responsible for much of the herd record keeping and data analysis. The number of dairy cattle in the UK is falling while beef suckler cow numbers are rising. Herd sizes are rising in both sectors and fewer personnel are now employed on cattle units than was the case in the past. While dairy cow milk yields are steadily increasing, fertility seems to be falling, in part due to pregnancy rates reducing by approximately 0.5-1.0% per annum and also probably due to poor oestrus detection rates on many farms. Veterinary involvement in cattle in the UK is decreasing due in part to the current economic crisis facing the industry, and partly due to the decreasing size of the national dairy herd. However, lost revenue due to falling fertility on many farms and the current development of farm assurance schemes requiring veterinary input, provides an opportunity for cattle veterinarians. Those wishing to move from reactive "fire-brigade" work towards more structured herd health programmes need to motivate their clients and convince them of the potential mutual benefits. In both dairy and beef suckler herds there is a need to control endemic diseases that may be contributing to poor fertility, this will be best achieved within a cohesive herd health and quality assurance framework, involving cooperation between the farmer, veterinarian and other interested parties. Technical advances in animal husbandry such as automated milking systems, and biosensors capable of automatically detecting milk progesterone levels and predicting time of ovulation without a need for oestrus detection, are likely to have a major impacts on fertility management in some dairy herds in the future. KEYWORDS: fertility review, fertility management, UK national herd, Daisy, NMR, herd health schemes, new technology.

CATTLE PRACTICE Since 1960 there has been a steady rise in the number of beef suckler cows in the UK from less than one million to the current level approaching two million. Dairy cow numbers rose from approximately 3.2 million in 1960 to peak in the early 1970s at close to 3.5 million. After remaining at around this level for almost ten years the size of the national dairy herd then began to decline with the introduction of milk quotas in 1984. The result is that there are now approximately one million less dairy cows in the UK than there was 25 years ago (Anon 1998). These long-term trends have continued with a general decline in the number of dairy cattle in the UK and a slight increase in the number of breeding beef suckler cows over the last 5 years. However, the general trend towards larger herds is probably far more significant when one considers possible effects on herd fertility. Tables 2 and 3 illustrate the change in structure of the national dairy and beef herds respectively between 1994 and 1999. BCVA 2001 VOL 9 PART 1 Between 1994 and 1999 there has been a reduction in the size of the national dairy herd of over 250,000 cows, this has been accompanied by a reduction in the number of herds of over 7,000. Approaching 5,000 of these herds were of less than 50 cows, with the remainder being predominantly herds of less than 100 cows. The result has been that the average dairy herd size has jumped from 66.9 to 73.0 cows over the same period (MAFF 2000). This trend is set to continue and it is projected that by 2005 there will be just 25,000 milk producers in the UK keeping 2.2 million cows, with the average herd size being 88 cows (Brigstocke 2000). The trend in the beef herds has also been towards fewer larger herds, with the average herd size increasing from 24.4 cows in 1994 to 27.4 cows in 1999, with approximately 2,500 less herds but an overall increase in the national breeding herd of about 142,000 suckler cows. The average 305-day milk yield of the dairy herd has risen over the last decade from approximately 5,000 l in 1990 to in excess of 6,000 l in 2000. Individual cows with 305-day lactation yields in excess of 10,000 l are becoming commonplace on UK farms and many herd average yields now exceed 7,000 l. However, the rapid fall in the value of cattle products has severely reduced or even eliminated profit margins over recent years. Both milk and beef were only worth on average 74% of their 1995 value in 1999! Net dairy farm incomes in 1999-2000 are estimated to be only about 25% in real terms (adjusted against retail price index) of their value in 1989-90 (MAFF 2000). In addition to the demise of many smaller herds a major effect of this economic downturn has been a reduction in the number of staff employed on cattle units. It is now commonplace for one individual to undertake all the day to day management of a 100 cow dairy herd; those with smaller herds generally have other enterprises or also work off the farm. In the USA and New Zealand one farm employee per 750,000 l of milk produced per 60 Table 1. The UK National Herd in the late 1990s (‘000 animals) 1995 1996 1997 1998 1999 Total Cattle and Calves 11,857 12,040 11,633 11,519 11,423 Dairy Cows 2,603 2,587 2,478 2,439 2,440 Beef Suckler Cows 1,840 1,864 1,862 1,947 1,924 In-calf Dairy Heifers 566 608 599 563 549 In-calf Beef Heifers 209 209 249 225 214 (Source: MAFF Statistics) Table 2. The number and size of dairy herds in the UK in 1994 and 1999 (‘000 cows or ‘000 holdings) Dairy Herd 1994 1999 Size (cows) Holdings Cows Holdings Cows 1 to 49 18.1 477 13.3 350 50 to 99 14.2 1,007 12.0 857 100 and over 8.2 1,229 8.2 1,230 TOTAL 40.5 2,713 33.4 2,437 Table 3. The number and size of beef suckler herds in the UK in 1994 and 1999 (‘000 cows or ‘000 holdings) Beef Suckler 1994 1999 Herd Size (cows) Holdings Cows Holdings Cows 1 to 19 44.1 329 39.8 328 20 to 49 18.2 564 19.1 594 50 and over 9.7 868 10.7 981 TOTAL 72.1 1,761 69.6 1,903 (Source: MAFF Statistics) (Source: MAFF Statistics)

CATTLE PRACTICE annum is a standard rule of thumb (Brigstocke 2000), if UK milk production is to be competitive in the current climate of free world trade, similar targets may have to be achieved. This will inevitably have an effect on levels of individual cow care, with associated implications for time-consuming tasks such as oestrus detection, and therefore, an impact on fertility management in addition to possible adverse effects on cow welfare. NATIONAL DAIRY HERD FERTILITY PERFORMANCE One of the major problems in monitoring and assessing trends in herd fertility in the UK is obtaining reliable data. There is no national database of information on cattle fertility, and the data available are subject to problems such as the underrecording of key information, particularly service dates and the lack of pregnancy diagnoses in many herds. Despite the fact that many farmers now have detailed records of their own herd performance, data are fragmented and there is no central collation of information. The two reasonably reliable sources of reproductive data in the UK are the National Milk Records (NMR) which records data on approximately 9,000 herds and the computer software programme Dairy Information System (DAISY) database originally produced by the University of Reading and now belonging to Agrisoft, NMR. National Milk Records Data Analysis of data from NMR recorded herds between January 1997 and September 2000 has shown that the average herd size of NMR herds has risen from 97 to 112 cows, and that the herd average yield has risen from below 5,500 l to approach 7,000 l (Figure 1). Over the same period the mean calving to first service interval has risen from 84 to 88 days, the calving to conception interval from 113 to 121 days (Figure 2) and the calving interval from 391 to 399 days (Figure 3). The pregnancy rate to first service (based on available PD data and non-return rates at 48 days) fell from 61.5% to 52.5% over the same period (Figure 4). It should be noted that changes were made to the way these pregnancy rate data were calculated in early 1999 resulting in a downward step in this figure of approximately 6%, unfortunately NMR have been unable to give a specific explanation of how these calculations were modified. Despite this, there seems to be a downward trend in first service pregnancy rate of approximately 3% over the last 3-4 years. BCVA 2001 VOL 9 PART 1 61 Figure 1. NMR data from approximately 9,000 UK dairy herds showing trends in mean herd size and milk yield between Jan. 1997 and Sept. 2000. 101 103 105 107 109 111 113 herd size (cows)…... Figure 2. NMR data from approximately 9,000 UK dairy herds showing the trend in calving to conception interval between Jan. 1997 and Sept. 2000. 116 118 120 122 124 ving to conception erval (days) Figure 3. NMR data from approximately 9,000 UK dairy herds showing the trend in calving interval between Jan. 1997 and Sept. 2000. 394 396 398 400 g interval (days)

CATTLE PRACTICE It is also clear from the NMR data for herds categorised by average yield, that fertility parameters and particularly pregnancy rates, are poorer in the higher yielding herds (Table 4). However, these herds also tend to be larger and it is not possible from the available data to determine which factor is most important, although it is likely that both increasing herd size and average yield contribute to poorer fertility. Although cull rates for failure to conceive are not available in the NMR database, and alterations in culling would obviously alter other fertility parameters, the data that are available seem to consistently show that there has been a fall in fertility over the last 3-4 years. BCVA 2001 VOL 9 PART 1 During 1997 and 1998 dairy farmers in the NMR recording system consistently inseminated around 70% of their herds with dairy semen and about 30% with beef semen. However, from early in 1999 the dairy inseminations began to decline and beef inseminations rise, in September 2000 dairy inseminations had fallen to nearly 60% with beef inseminations exceeding 35%. In addition to the increase in the size of the national beef suckler herd and the shrinking national dairy herd there are many possible reasons for this change in insemination patterns. The most important is probably the removal of the subsidised payment "calf processing aid scheme" in the summer of 1999 which resulted in a rapid fall in the value of dairy bull calves, stimulating a move towards more beef inseminations in dairy herds. There is a tendency to inseminate a greater proportion of the herd with dairy semen in the higher yielding herds. This may be due to a number of factors; these herds probably breed more of their own replacements, they may also sell excess dairy heifers or the herds may be expanding more rapidly than smaller herds. Although the NMR data set does not provide information on longevity, one might also speculate that cows remain in these high yielding herds for a shorter time and thus proportionately more replacements are needed. This is expected due to higher levels of voluntary culling to improve yield and increase their rate of genetic improvement and more involuntary culling for reasons including poorer fertility than that seen in smaller herds (Table 5). 62 (*Based on available PD data and non-return rates at 48 days postservice, the method of calculation altered in April 1999 resulting in a downward shift of approximately 6% in pregnancy rate to first service). 56 58 60 62 64 ate to first service* (%) Figure 4. NMR data from approximately 9,000 UK dairy herds showing the trend in pregnancy rate to first service* between Jan. 1997 and Sept. 2000. Table 4. NMR aggregate herd data as of June 2000. Average herd yield (litres) Mean herd size Calving interval (days) Mean calving to 1st service interval (days) Pregnancy rate to 1st service (%) Services/ conception Calving to conception (days) 4500 - 5500 78 394 90 59.8 1.46 117 5501 - 6500 95 393 87 58.5 1.54 114 6501 -7500 98 397 87 52.8 1.68 119 7501 - 8500 114 401 88 50.8 1.70 122 8501 -9500 111 402 92 46.8 1.74 127 9501 - 10500 139 404 89 44.9 1.85 127 10501 + 130 409 95 38.7 2.01 140 Table 5. NMR data showing percentage of dairy and beef inseminations within dairy herds of different average yields, as of June 2000. Average herd yield(litres) % served to dairy bulls % served to beef bulls 4500 - 5500 69.8 26.9 5501 - 6500 57.7 41.0 6501 -7500 66.0 33.9 7501 - 8500 65.8 34.1 8501 -9500 70.4 27.2 9501 - 10500 77.8 22.2 10501 + 78.8 21.1

CATTLE PRACTICE DAISY Data Esslemont and Kossaibati (2000a) have reported fertility performance in 52 Holstein-Friesian dairy herds averaging 168 cows in England over a period of 11 calving seasons (1987/88 to 1997/98). The calving to first service interval gradually increased from 70 to around 77 days (Figure 5). The proportion of cows re-served within 16 to 28 days of first service declined slightly over the study period, with an average of 50.4%. The pregnancy rate to first service slipped from around 50% in the early seasons of the study to 43.7% in 1997/98 (Figure 6) and the pregnancy rate to all services declined from 49% to 42.5% during the same period, with an overall average value of 46.4%. Following the same trend, the number of services per conception increased from an average of 1.96 in 1987/88 up to 2.36 in 1997/98, with an overall average of 2.13. The calving to conception interval increased from 96.4 days in 1987/88 season to 110.4 days in the 1997/98 season (Figure 7), with an overall average interval of 103.4 days. Similarly, calving interval tended to increase from an average of 379.4 days in 1987/88 to 390.2 days in 1997/98 (Figure 8), achieving an overall average interval of 384.7 days. BCVA 2001 VOL 9 PART 1 The culling rate due to failure to conceive in this study was relatively constant over the 11 calving seasons at 11.5% on average. The overall culling rate in the UK national dairy herd is considered to be around 25% (Esslemont et al 1997) although during the height of the BSE crisis this reached 30% (Forbes 1999). Other data In a small scale study undertaken by workers at the University of Nottingham and the Roslin Institute, the reproductive performance of 714 HolsteinFriesian dairy cows from seven commercial dairy units was closely monitored between October 1995 and June 1998 using twice weekly milk progesterone determinations (Royal et al 2000). Defined endocrine parameters such as the interval to commencement of postpartum luteal activity, inter-ovulatory intervals, and length of luteal and inter-luteal intervals were used to investigate the fertility in this sample of UK dairy herds. A comparison was undertaken between the results of this 1995-98 trial with a database of milk progesterone profiles from a previous study of 2503 lactations from 1682 dairy cows in 20 herds undertaken between 1975 and 1982. Between 1975-82 and 1995-98, pregnancy rate to first service declined from 55.6% to 39.7% at an 63 Figure 5. DAISY data from 52 dairy herds in England showing an increase in calving to first service interval over eleven breeding seasons (1987/88-1997-98) (Esslemont and Kossaibati 2000a). 72 74 76 78 to first service interval (days) Figure 6. DAISY data from 52 dairy herds in England showing a decrease in pregnancy rate to first service over eleven breeding seasons (1987/88-1997-98) (Esslemont and Kossaibati 2000a). 44 46 48 50 52 gnancy rate to first service (%) Figure 7: DAISY data from 52 dairy herds in England showing an increase in the calving to conception interval over eleven breeding seasons (1987/88-1997-98) (Esslemont and Kossaibati 2000a)s. 100 102 104 106 108 110 112 Calving to conception interval (days) Figure 8: DAISY data from 52 dairy herds in England showing an increase in calving interval over eleven breeding seasons (1987/88-1997-98) (Esslemont and Kossaibati 2000a). 382 384 386 388 390 392 ving interval (days)

CATTLE PRACTICE average rate approaching 1% per year. This decline in pregnancy rate was associated with an increase in the proportion of animals with one or more atypical ovarian hormone pattern. There was an increase in the mean luteal phase length from 12.9 (S.E. 0.09) to 14.8 (S.E. 0.17) days and an increase in interovulatory intervals from 20.2 (S.E. 0.1) to 22.3 (S.E. 0.2) days. The decline in fertility was also reflected in traditional measures of fertility since although the interval to first service remained relatively unchanged (74.0 to 77.6 days), calving interval lengthened from 370 to 390 days. Discussion of dairy herd fertility data Three sources of fertility data have been considered in this review, the first is an extensive database containing limited information on approximately one million cows or 40% of the UK dairy herd. These data, while representing a large sample, are based mainly on calving dates, service dates and returns to service from the larger higher yielding herds. The accuracy of some parameters such as pregnancy rate is thus questionable and direct comparisons with the data held in the DAISY databases is not possible. DAISY hold very detailed individual cow data on a much smaller sample of herds. While the data are considered to be accurate the sample size is relatively small and DAISY recorded herds may not be representative of the dairy cattle population. It is to be expected that DAISY recorded herds are better managed than the average herd in the UK. The third study included here from the University of Nottingham is a detailed investigation of reproductive physiology based on regular milk progesterone assays in seven commercial herds. These three sources of information can not be directly compared as they are derived from very different samples of the population and cover differing time frames. However, it seems to be evident from all three that the fertility of the national dairy herd in the UK is declining. There seems to be a downward trend in pregnancy rates in the order of 0.5-1.0% per annum and increases in all of the generally recognised measures of fertility such as calving to first service interval, calving to conception interval and calving index. This fall in fertility has coincided with changes in the industry that have resulted in higher milk yields, larger herds and falling staff numbers on UK dairy farms. BCVA 2001 VOL 9 PART 1 NATIONAL BEEF HERD FERTILITY PERFORMANCE There are no reliable data on the fertility of the national beef suckler herd, the majority of herds use natural service and so indirect measures of fertility such as length of calving season and culling rate have to be used to assess fertility. Statistics from the Meat and Livestock Commission provide some limited indication that fertility may be declining at least in lowland and hill units where calving periods are extending and barren cow numbers increasing (Table 6) (Anon 1996, Anon 1999a). Furthermore, there is considerable anecdotal evidence that fertility may be declining, farmers who use artificial insemination (AI) are finding it increasingly difficult to observe cows in oestrus, and are facing increased culling rates for failure to conceive or extended calving patterns. Where beef suckler producers wish to use AI, problems with oestrus detection have prompted the increased use of controlled breeding programmes with repeated oestrus synchronisation and fixed-time AI (Penny et al 1997, Penny et al 2000). These programmes remove the need for oestrus detection and have the advantage of allowing farmers to use superior bulls via AI and remove the risk of bull infertility, venereal transmission of diseases such as Campylobacter fetus venerealis and accidents involving bulls. Despite the possibility of using AI in suckler beef herds, with or without oestrus synchronisation and fixed-time AI, the majority of farmers still use natural service. Many farmers hire or borrow bulls, and few take precautions against the introduction of infectious diseases, with the result that Campylobacter fetus venerealis infection seems to be increasing at least in Scotland and the North of England (Caldow and Taylor 1997). REASONS FOR DECLINING FERTILITY The declining fertility seen in the UK cattle herd may be due to a number of factors. These include high levels of peri-parturient disease (Peeler et al 1994a & b), inadequate nutrition (Webb et al 1997, Wathes et al 1998, Webb et al 1999), increasing genetic merit for milk production (Nebel and McGilliard 1993, Lamming et al 1997, Lucy and Crooker 1999), infectious diseases or numerous other independent or 64 Table 6. Indirect measures of herd fertility in suckler herds*. 1995 1998 Lowland Upland Hill Lowland Upland Hill Calving Period (weeks) 12 12 12 14 11 11 Barren Cows (per 100 mated) 9 7 7 7 7 11 (Source: MLC Statistics) *data represents average for herd type in MLC Beefplan Surveys, sample sizes range from 93 to 23 herds (Anon 1996, Anon 1999a))

CATTLE PRACTICE interrelated factors. Specific breeding management changes such as the increase in the use of do-ityourself AI, with variable amounts of training of personnel, may also be significant (Howells et al 1999). In dairy herds increasing milk yields and increasing herd sizes are almost certainly contributing to the problem. The fact that the majority of beef suckler cows in the UK are F1 Beef x Dairy hybrids may also be significant. If modern high yielding high genetic merit Holstein-Friesian dairy cattle are inherently less fertile, this trait may be passed to the beef suckler cows. The overall effect is greater difficulty in getting cows in calf and increased costs of trying to do so. It is also highly likely that the decreasing availability of labour on farms (Farrar and Franks 1998, Andrews 2001) is resulting in reduced labour hours per cow per year. This may contribute to inadequate husbandry on some units, leading to declining levels of efficiency of heat detection, as well as less attention to detail in other areas. In these times of expensive labour and drastically falling profit margins, with many UK milk producers actually trading at a loss, farmers often question the costeffectiveness of spending time simply observing cows to detect signs of oestrus. INFECTIOUS DISEASE Many infectious diseases which are known to be detrimental to fertility such as bovine virus diarrhoea virus (BVDV), infectious bovine rhinotracheitis (IBR), leptospirosis, and Neospora caninum are endemic in the UK. In addition, the use of bulls in suckler herds and their increased use in dairy herds to remove the need for oestrus detection is resulting in a resurgence of previously rare infectious conditions such as Campylobacter fetus venerealis (Caldow and Taylor 1997). Over recent years there have been both government and privately run cattle health schemes to encourage the control of BVDV, IBR, leptospirosis, enzootic bovine leucosis and Johne's disease. Of these BVDV, IBR and leptospirosis are known to reduce fertility and/or cause abortion. There have also been a number of commercial campaigns by pharmaceutical companies marketing vaccines against BVDV, IBR and leptospirosis. Despite this, there is little evidence to suggest that these diseases are being adequately controlled in the UK, or that the control measures that are being adopted are having any impact on fertility at the national level. This may be due in part to poor uptake of the health schemes by the industry. However, it is to be hoped that recent moves to pull the numerous schemes together under one unifying standard "Cattle Health Certification Standards (UK) - CheCS" will improve the situation (Duncan 2000) and lead to a unified national disease control strategy BCVA 2001 VOL 9 PART 1 for BVDV, IBR, leptospirosis and Johne's disease. Individual herds undoubtedly benefit from specific disease control measures and vaccination strategies, but what is needed is a national control programme for these and other economically important diseases. There is statutory control of Brucella abortus in the UK under the control of the Ministry of Agriculture; England, Scotland and Wales have been essentially free of the disease for many years, although there was a small outbreak in 1993. However, there have been recent outbreaks of brucellosis in Northern Ireland, with 29 herds affected in 1998 (Anon 1999b). THE COST OF POOR FERTILITY Esslemont and Kossaibati (1997) studied 50 dairy herds in England in the early 1990s and found that the annual culling rate was 23.8%, with poor fertility being the most common reason for culling (36.5% of disposals). They estimated that producers were losing £770 for every cow culled over an optimum of 18% per annum. In addition they recognised that an extended calving interval over 368 days cost the farmer £3/cow/day and that every service over a target of 1.8 per pregnancy cost an additional £20 (Kossaibati & Esslemont 1997). Based on these figures an average herd in their study was losing £76/cow/year, with herds in the worst quartile losing over £140/cow/year. Losses of this magnitude allow considerable scope for improvement and should stimulate both farmers and veterinarians to work together to improve the situation. However, to date, many farmers still do not have comprehensive fertility control programmes in place to minimise these losses. In fact many of the financial losses could be easily avoided by undertaking simple tasks such as pregnancy diagnosis. Wassell and Esslemont (1992) found that only a third of veterinary practices seeing cattle ran fertility programmes, and many of those that did ran them on only a small number of farms. In addition, a study by Singleton and Dobson (1995) showed that 23.5% of cull cows in an abattoir in South West England were pregnant. In 51% of cases the farmers who sent pregnant cows to slaughter were unaware that they were pregnant, it was estimated that culling errors of this type cost the UK cattle industry over £30 million per annum (Singleton and Dobson 1995). Given the magnitude of the losses attributable to poor fertility and culling errors, and the fact that fertility is falling in the national herd as a whole, one would expect that it would be fairly easy to persuade farmers of the merits of veterinary intervention. However, this is not always the case and while there are no reliable data on the number of herds involved in fertility control programmes it is evident that many farmers see this type of routine work as an expense they can avoid during these financially difficult times. 65

CATTLE PRACTICE THE FUTURE The future of veterinary involvement in cattle fertility in the UK is dependent on the future structure of cattle practice. It is likely that those veterinary practices that maintain an interest and involvement with cattle will either become primarily consultants or act as first opinion veterinarians working with the guidance of consultants. In many areas farmer's skill levels are increasing, paraprofessionals are becoming involved in what were traditionally veterinary tasks (e.g. pregnancy diagnosis by ultrasound examination), and the demand for "fire-brigade" work is declining. More veterinarians' time in the future will be devoted to herd health work where the professional fee for the veterinarians' intervention is offset against the returns from the whole herd. Increasingly it will become uneconomic for veterinarians to spend time investigating and treating individual commercial animals. Herd Health Schemes Dairy herd health schemes concentrating on herd fertility have been operated in the UK for over 20 years. However, the uptake of these schemes by farmers has been relatively limited. In a study of herd health schemes in the early 1990s, Wassell and Esslemont (1992) found that less than 12% of dairy herds were provided with routine fertility visits. Similar schemes in the beef sector are even rarer, with many beef suckler producers not even bothering to have cows examined for pregnancy. The emphasis in herd health schemes is currently moving away from purely performing fertility related tasks. All encompassing schemes to monitor the health and welfare of the herd are being developed within the framework of quality assurance programmes (Kruif 1998, BCVA 1999). There is a growing realisation amongst successful farmers that they must optimise returns from their herd to remain in business. This requires control of diseases likely to affect all aspects of production and optimisation of fertility within a predetermined herd health management strategy. This can best be achieved by considered interventions within the structure of a well-managed herd health and quality assurance scheme. Regardless of the underlying causes of falling fertility in the national herd, progress may be made to maintain or improve fertility if a multidisciplinary approach is undertaken. This should involve the farmer, stockman, veterinarian and other interested parties such as dairy nutritionists (Kelly and Whitaker 1999). In the longer term including fertility traits in the selection indices for future breeding programmes is also likely to produce benefits (Simm 1999). BCVA 2001 VOL 9 PART 1 Farmer motivation There are considerable benefits to be gained from improvements in herd health; a farmer with 77 cows, who went onto the DAISY scheme and adopted a planned approach to management, saw his farm profits improve by £13,000 in 2 years. It was estimated that £6,000 of this came from improved fertility management alone (Esslemont and Kossaibati 2000b). This in itself should be enough to motivate farmers to undertake schemes of this type. The economic appraisal of herd health schemes has been extensively reviewed previously (Esslemont and Peeler 1993, Esslemont 1995) and will not be discussed in-depth here. However, it is important to realise that the financial benefits are often hidden and not immediately apparent to the farmer unless the herd records are analysed regularly and benefits quantified in monetary units. It is therefore essential that accurate herd records be maintained and that they are analysed and acted upon regularly (Varner and Brand 1996, Bailey et al 1999). This is greatly aided by the use of specialised computerised recording systems such as DAISY (Agrisoft, NMR), InterHerd (Agrisoft, NMR) or DairyCHAMP (University of Minnesota) or other software produced specifically for on-farm use. However, with modern software packages such as Microsoft Office containing easy to use spreadsheet programs it is possible to construct customised spreadsheets to undertake most, if not all, the analysis that a farmer or veterinarian require to monitor fertility within a herd (Logue et al 2000). The interpretation and understanding of herd records can also be greatly enhanced by the use of computer generated graphs and charts, for example those quickly and easily produced by computer programs such as Microsoft Excel (Hendry 1999). The proper operation of herd health schemes leads to benefits for the cows, farmer and veterinarian, and is equally applicable to beef suckler herds as it is to dairy herds. However, without regular assessment of progress motivation of both the farmer and the veterinarian is likely to fall. New technologies and industry advances The decreasing availability of staff on farms in the UK is presenting a real challenge to many farmers and veterinarians as they attempt to maintain and improve herd fertility. Over recent years there have been numerous technological developments that can help, particularly aids to oestrus detection such as the KaMaR heat mount detector, pedometers and milk progesterone assays (Peters and Ball 1995). It is probable that in the future accurate and reliable automated systems to assess the cow's physiological 66

CATTLE PRACTICE state using biosensors will be developed (Mottram 1997). New developments of this type may allow automatic milk progesterone assays to be performed while cows are being milked, allowing the timing of ovulation to be accurately predicted and removing the need for oestrus detection. In addition technologies such as automated milking may become more widespread freeing stockmen from routine mundane tasks and allowing them to concentrate on improving cow care. Until technical developments of these types become available, herd owners will continue to use the tools at their disposal such as conventional milk progesterone assays to aid breeding management (Watson 1996, Watson 1997). It is also likely that pharmacological interventions to synchronise ovulation such as the Ovsynch/Intercept regimens in dairy cattle (Borsberry 1998), and Crestar (Intervet UK) in beef suckler cows and heifers (Penny et al 1997) will continue to be used to negate the need for oestrus detection in many herds. CONCLUSIONS Available data suggest that fertility in UK cattle appears to be falling. The aim of the veterinary profession should be to help and motivate farmers to get their cows in-calf without putting unrealistic burdens on them by expecting the levels of individual animal care, and oestrus detection, that were possible when more staff cared for far fewer cows in smaller herds. This may be achieved in part by close cooperation between the farmer and veterinarian to control endemic diseases and optimise management of the herd. In the future, new technological developments will go some way to offset the reduction in manpower on farms and improve health, production and fertility in the UK cattle herd. ACKNOWLEDGEMENTS The author would like to thank Dr Dick Esslemont and Dr Mohamad Kossaibati for allowing him access to their paper "Trends in Fertility in 52 dairy herds over 11 seasons" prior to publication. Special thanks are also due to Catherine Smith of NMR for making available data from the NMR database for analysis and Professor Julie Fitzpatrick and Dr Nick Jonsson for their constructive comments on the paper. This paper was initially prepared following an invitation to speak to the Portuguese Buiatrics meeting in November 2000 and is reproduced here by kind permission of the Portuguese Buiatrics Association. The paper has previously been published in Portuguese: Barrett, D.C. 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Galway, Ireland, September 1999. pp 27-28 67

CATTLE PRACTICE MAFF (2000) Various MAFF publications and statistical reports. www.maff.gov.uk Mottram T. (1997) Automatic monitoring of the health and metabolic status of dairy cows. Livestock Production Science 48: 209-217 Nebel R.L., McGilliard M.L. (1993) Interactions of high milk yield and reproductive performance in dairy cows. Journal of Dairy Science 76: 3257-3268 Peeler E.J., Otte M.J., Esslemont R.J. (1994a) Recurrence odds ratios for periparturient disease and reproductive traits of dairy cows. British Veterinary Journal 150: 481-488 Peeler E.J., Otte M.J., Esslemont R.J. (1994b) Interrelationships of periparturient diseases in dairy cows. Veterinary Record 134: 129-132 Penny C. D., Lowman B.G., Scott N.A., Scott P.R. (1997) Repeated oestrus synchrony and fixed-time artificial insemination in beef cows. Veterinary Record 140: 496-498 Penny C. D., Lowman B.G., Scott N.A., Scott P.R. (2000) Repeated oestrus synchronisation of beef cows with progesterone implants and the effect of a gonadotrophin-releasing hormone agonist at implant insertion. Veterinary Record 146: 395-398 Peters A.R., Ball P.J.H. (1995) Reproduction in Cattle 2nd Ed. Blackwell Science, Oxford. Royal M.D., Darwash A.O., Flint A.P.F., Webb R., Woolliams J.A., Lamming G.E. (2000) Declining fertility in dairy cattle: changes in traditional and endocrine parameters of fertility. Animal Science 70: 487-501 BCVA 2001 VOL 9 PART 1 Simm G. (1999) Genetic improvement of cattle and sheep. Farming Press, Miller Freeman UK Ltd. Ipswich. Singleton G.H., Dobson H. (1995) A survey of the reasons for culling pregnant cows. Veterinary Record 136: 162-165 Varner M., Brand A. (1996) Monitoring reproductive performance: Decision making and follow-up In: Herd Health and Production Management in Dairy Practice. Ed. A. Brand, J.P.T.M. Noordhuizen, Y.H. Schukken. Wageningen Pers, Wageningen pp 313-332 Wassell T.R., Esslemont, R.J. (1992) Survey of the operation of dairy herd health schemes by veterinary practices in the United Kingdom. Veterinary Record 130: 260-263 Wathes D.C. Robinson R.S., Pushpakumara A., Cheng, Z,. Abayasekara D.R.E. (1998) Nutritional effects on reproductive performance in dairy cows. Cattle Practice 6: 371-377 Watson C. L. (1996) Milk progesterone analysis - An underused asset in fertility control of the dairy cow. Cattle Practice 4: 277- 280 Watson C. L. (1997) "Playing the odds to get results" Milk progesterone sampling and fertility control in the dairy cow. Cattle Practice 5: 373-377 Webb R., Garnsworthy P.C., Gong J.G., Gutierrez C.G., Logue D., Crawshaw W.M., Robinson J.J. (1997) Nutritional influences on subfertility in cattle. Cattle Practice 5: 361-367 Webb R., Royal M.D., Gong J.G., Garnsworthy P.C. (1999) The influence of nutrition on fertility Cattle Practice 7: 227-234 68

BCVA 2001 69 CATTLE PRACTICE VOL 9 PART 1 caninum antibody was 17.9% in 107 neonates, 26.2% in 233 yearling heifers and steers, 39.1% in 218 older heifers and 26.9% in 465 milking cows. Serological reactivity was associated with production grouping on the farm, with the greatest risk of serologic reactivity appearing in the yearling and older heifers. Within the milking herd there was a significant (P=0.0008) non-linear increase in seroprevalence with increasing longevity, suggesting that animals that remained in the herd longest had the greatest risk of exposure. The evidence suggests that at least in this herd horizontal transmission is a significant route of infection. There was one aged female dog resident on the farm. We still have a lot to learn about the epidemiology of this parasite; these papers show it can act very differently in different herds. ACUTE PHASE PROTEINS There is growing interest at the present time in the use of acute phase proteins (APP) as markers of inflammation and infection in the monitoring of animal health and welfare and food safety. Eckersall (2000) has reviewed this whole subject area in the Irish Veterinary Journal. This review explains that the acute phase response is the immediate reaction of an animal to infection, inflammation or trauma and is stimulated by pro-inflammatory cytokines such as interleukins 1 and 6 and tumour necrosis factor-α. During the response, circulating levels of a number of plasma proteins increase, and their concentrations can be used to provide valuable diagnostic and prognostic information. In cattle, haptoglobin and serum amyloid A are the most sensitive and therefore useful of the APP. As well as aiding in the diagnosis of clinical disease, measuring levels of these proteins may have an important future role in monitoring animal health during production, as moderately elevated serum concentrations will indicate the presence of sub-clinical disease. In addition, monitoring the level of APP at slaughter would identify animals with active disease processes, which could then be removed from the food chain. CALF MORBIDITY A study of the risk factors for high herd level calf morbidity from birth to weaning in beef herds in the USA has recently been reported (Sanderson and Dargatz 2000). Questionnaire data were analysed from 2490 beef herds, comprising 77.6% of herds and 85.7% of beef cows in the USA. Farmers were Cattle News 2000 Parts 10-12 Barrett D. C., Department of Veterinary Clinical Studies, University of Glasgow Veterinary School, Bearsden Road, Bearsden, Glasgow, G61 1QH. INTRODUCTION This paper follows on from Cattle News 2000 Parts 7-9 published in the October 2000 issue of Cattle Practice (8: 433-437). The material covered here is reproduced from the Cattle News columns that appeared in the UK Vet in the second half of 2000 and the early part of 2001. In writing the BCVA Cattle News column it is the author's aim to provide a summary of some of the more interesting, and topical, recent publications related to Cattle Health and Production which are not readily available to those remote from a veterinary reference library. NEOSPORA CANINUM It seems that there are new papers on Neospora infection of cattle appearing in the literature so frequently at the present time that we return to the subject in almost every edition of Cattle News. Here we consider two papers published in the Canadian Veterinary Journal (Bergeron et al. 2000) and Veterinary Parasitology (Dyer et al. 2000). The first of these papers is an investigation into vertical and horizontal transmission of N. caninum in dairy herds in Québec. The pedigree of each cow tested from 23 dairy herds was investigated on the dam's side to identify the serological status of related individuals. The seroprevalence amongst animals in the study herds varied from 4.3% to 61.8% with a mean seroprevalence of 21.9% in the study population. The overall rate of vertical transmission was estimated to be 44.4 %, varying from 0% to 85.7% between herds. Seven cases of horizontal transmission were identified in 6 of the 23 herds studied. The estimated vertical transmission rate varied from herd to herd, but appeared to be higher in herds with a high prevalence of seropositive animals. The correlation coefficient between vertical transmission rate and prevalence of seropositive animals was 0.74 (P<0.0001). No association was identified between the number of dogs on the farms and identification of horizontal transmission. Although horizontal transmission was identified in 6 herds, it does not appear to be a significant route of infection in this study. In contrast to the Canadian study, a cross-sectional consensus survey of 1029 cattle in a dairy herd with endemic Neospora-induced abortion in the USA has revealed that horizontal transmission seems to predominate in the herd. There was no clear relationship between the serological status of dam and offspring. In this herd the prevalence of N.

CATTLE PRACTICE asked to give general information about the herd, as well as estimate the number of calves experiencing morbidity from respiratory disease, diarrhoea, keratoconjunctivitis and lameness and the number of cows and heifers experiencing dystocia. The results showed that any level of dystocia in a herd was associated with increased odds of being a highmorbidity herd (≥10%) compared with herds with no dystocia. Having >70% of cows and heifers calving in confinement also increased the odds of being a high-morbidity herd. This study has quantified what many clinicians probably already suspected, namely that many calf problems start at, or before, the moment of birth. Results presented here show that the effects of increased levels of dystocia are responsible for high morbidity levels in approximately 41% of the high-morbidity herds. They also show that 46% of the herds with high morbidity could be moved to the low-morbidity category (<10%) by eliminating the effects of dystocia and confined calving. In short this suggests that if we want healthy calves, we must make every effort to prevent dystocia and calve cows at pasture when ever possible. A second interesting study (Brückmann et al. 2000) looks at the concentrations of growth hormone (GH), cortisol, luteinizing hormone (LH) and insulin in early-postnatal calves affected with diarrhoea. Blood samples were collected from 10 male and 10 female calves every 15 minutes for 6 hours at Days 3, 9 and 21 of life. Animals were classified into three groups. Group 1: healthy controls (n=9), Group 2: calves affected with spontaneous diarrhoea at Day 9 (n=7) and Group 3: calves affected with spontaneous diarrhoea at Days 3 and 9 (n=4). Mean GH concentrations in the calves in Groups 2 and 3 had increased by Day 3 compared to control calves. Cortisol levels of calves in all groups were highest at Day 3 and then decreased. However, the cortisol concentrations were lower at Day 3 in animals in Groups 2 and 3 than in the controls. Pulsatile LH release was detectable at Days 9 and 21 only in healthy calves. Insulin increased at Day 9 during diarrhoea. Low cortisol concentrations were related to higher susceptibility toward diarrhoea in neonatal calves. Increased GH concentrations were evident even before the appearance of clinical diarrhoea. It is suggested therefore that GH may play an important role in activating the body's defences against diarrhoea and in intestinal healing. The onset of pulsatile LH release was delayed in the diarrhoeic calves. This study has shown that even mild diarrhoea may alter the concentration of reproductive and metabolic hormones in the early postnatal calf. Whether these hormonal disturbances have consequences for later growth and reproductive performance remains to be investigated. This work may be beginning to shed some light on why calves BCVA 2001 VOL 9 PART 1 experiencing disease in early life often never seem to fully recover and become "poor doers". QUALITY ASSURANCE SCHEMES An investigation undertaken in 1993 in the USA tested the hypothesis that dairy farms certified in their Milk and Dairy Beef Quality Assurance Program (QAP) were more likely to use prudent drug management practices than farms not in the scheme (Gibbons-Burgener et al. 2000). The study population consisted of 141 Michigan dairy farms of which 74 were not certified on the scheme. Dairy farmers were asked to complete a self-administered questionnaire focussing on herd health management, drug use, record keeping, personnel management, and descriptive characteristics of their farm. The results suggested that farms adopted specific management practices irrespective of certification. The authors conclude that the QAP appeared to have been associated with the adoption of only a few prudent drug use practices and that veterinary care would benefit from the development and encouragement of better record keeping on farms. Perhaps not surprisingly this all sounds rather familiar. The better farmers will want to adopt best practice regardless of QAP; others will require considerable motivation and encouragement. The simple act of having a scheme in place may not in itself bring about improvements unless the motivation is there. The carrot and stick comes to mind again! BEHAVIOUR AND WELFARE There has been debate over recent years about the welfare implications of early separation of dairy calves from their dams. However, there has been little objective research to inform the debate. This is changing with the publication of the first in a series of papers from a group in British Columbia (Weary and Chua 2000). Their study set out to investigate the effects of age of separation on the behavioural responses of the dairy cow and calf. Calves were separated from their dams at 6 hours, 1 day or 4 days after birth (n=9 cow-calf pairs in each group) and their behaviour was video- and audio-taped from 1 hour pre-separation until 21 hours post-separation. Calves separated at older ages made significantly more movements in the pen, spent more time standing and spent more time with their heads out of the pen, than calves separated sooner after birth. A similar pattern was seen with the cows. After separation, cows in the 4-day group called approximately four times that of those separated at 6 hours or 1 day. Calves separated at older ages tended to require fewer days of treatment for scouring, but calf weight gain and cow milk production did not differ between the treatment groups. The authors 70

CATTLE PRACTICE conclude that behavioural responses of both cow and calf increased in relation to calf age at separation. However, there may be health benefits in delaying the time of separation. It is evident from the paper that the calves separated later are likely to have received more colostrum. However, it is not clear if this wholly explains the enhanced health of the later separated calves or if other factors are involved. Galindo and Broom (2000) have investigated the relationship between social and individual behaviour of dairy cows and the occurrence of lameness in three herds. The herds consisted of 50,70 and 90 HolsteinFriesian cows housed in cubicles. The cubicle:cow ratio was 1:1 in all three herds. Their findings show that low-ranking cows spent less time lying and more time standing still and standing half in the cubicles than middle and high-ranking cows. As the time spent standing half in the cubicles increased, the number of soft tissue lesions increased and as total time standing increased the number of cases of lameness increased. The survival rate to lameness for low-ranking cows was significantly lower than for middle or highranking individuals. Less than 40% of low-ranking cows avoided lameness during the housing period compared with the survival rates of 67% and 82% for middle and high-ranking cows. While this may not be a surprise, it does underline that we should attempt to identify low ranking cows and heifers and offer them some protection if we are serious about controlling lameness, particularly in larger herds. RESPIRATORY DISEASE A Dutch study attempted to quantify the risk factors for respiratory disease in dairy youngstock using expert opinion (Fels-Klerx et al. 2000). This was considered necessary, as many of the previous epidemiological studies undertaken elsewhere in the world may not be relevant to dairy youngstock in the Netherlands. Twenty-one individuals considered to be experts in the field of bovine respiratory disease (BRD) were consulted in the study. Although numerous risk factors were considered, for calves 0- 3 months of age the most important were thought to be poor air circulation and the purchase of cattle. The latter risk factor was also considered as having the highest impact on the incidence of severe outbreaks of disease in youngstock aged 3-6 months, whereas a previous case of BRD was considered to be the most important risk factor for mild outbreaks. Outbreaks, both mild and severe, in dairy youngstock aged 6-24 months were perceived to be influenced most by air circulation. It seems that the Dutch experience is not that different from the UK. In these days of increasing interest in disease control and Herd Health Plans, a paper on the airborne transmission of BHV-1 in calves may be of interest to those advising on its control. Mars et al. (2000) report the result of a small study investigating BCVA 2001 VOL 9 PART 1 the spread of two BHV-1 virus strains. Five calves were experimentally infected with one of two strains of virus and then placed 4 m from five susceptible sentinel calves. Transmission was detected using virus isolation, BHV-1 specific PCR and serology. Only one of the strains (Lam) was reliably transmitted under these conditions. That strain was transmitted to all the sentinel calves within 3 weeks. The probability per day of a sentinel becoming infected over a 4m distance was 0.15. The duration of virus excretion was 8 days. Thus the infection rate was calculated to be 8 x 0.15=1.18. In other words, on average 1.18 susceptible calves would be infected by one infectious calf at a distance of 4m, or the transmission ratio R between two groups of cattle at 4m distance is 1.18. Extrapolation from these data suggests that R<1 at a distance of 4.4 m and R<0.5 at a distance of more than 6.2 m. Therefore, at least for the Lam virus strain, it should be possible to prevent the spread of infection by separating cattle by relatively short distances. It is often said that stress is a risk factor for respiratory disease. However, what we mean by stress is often unclear, as is its mode of action. In a further study using BHV-1 strain Lam the stress associated with social isolation of veal calves was investigated (Reenen et al. 2000). Group housed specific pathogen free veal calves (n=8) were inoculated at 12 weeks with BHV-1, half were immediately socially isolated to prevent all physical contact with other calves. Their clinical, virological and serological responses to BHV-1 and adrenocortical reactivity to exogenous ACTH were examined. The isolated group showed a diminished fever and clinical response, and delayed virus excretion when compared with the group-housed calves. Four weeks after isolation, basal cortisol levels and the integrated cortisol response after administration of a low dose of ACTH were significantly depressed in socially isolated calves. It is suggested that this is due to desensitisation of the hypothalamo-pituitary-adrenal axis, in response to a stress-induced rise in ACTH and cortisol, and that the earlier stress-induced rise in cortisol may have diminished the clinical signs and development of fever in the socially isolated (stressed) calves. Stress may therefore not always be bad! A group from Dublin have reported a polymerase chain reaction (PCR) assay for the detection of BHV1 based on the selection and amplification of a portion of the viral thymidine kinase (tk) gene (Moore et al. 2000). They report that the PCR is more sensitive and independent of sample quality than either virus isolation or FAT, and is faster than virus isolation. This assay would also permit discrimination between animals naturally infected with wild type BHV-1 and those vaccinated with the tk-BHV-1 strain but not other vaccine strains such as 71

CATTLE PRACTICE those based on glycoprotein gene deletions. The assay is also capable of detecting BHV-5, a virus previously reported to have caused encephalitis in Australia, Canada, Argentina and Hungary, and differentiating it from BHV-1. The development of rapid and highly specific assays of this type is to be welcomed. If commercially available in the future, they along with marker vaccines, may offer us new tools with which to combat BHV-1 in the national herd. TB CONTROL AND ERADICATION Once again we return to the thorny issue of TB control as further papers appear in the literature. Firstly there are two articles in the medical literature which critically appraise bovine TB control and eradication strategies (Hancox 2000a & b). In these articles the author reviews published material on bovine TB control strategies from various parts of the world set within the context of the pathogenesis of tuberculosis in both cattle and humans, and also in light of the epidemiology of bovine TB. The problems of TB test sensitivity and specificity are discussed, as are the particular problems that arise in eradication programmes as the TB incidence falls to very low levels in the population. While not denying that badgers may be infected with bovine TB in problem areas, it is concluded that this is an unlikely cause of herd breakdowns as a minimum dose of 400,000 bacilli may be required to establish infection in cattle and infected badger sputum only contains 200,000 bacilli/ml. The view is taken that, "it is quite extraordinary that the importance of cattle-to-cattle transmission is seriously questioned". The author concludes that the current rise in levels of bovine TB in the UK is due to premature relaxation of annual testing in some areas and inadequate movement restrictions. The risk to human health posed by the increasing incidence of TB in cattle is also discussed; the view is taken that pasteurisation of all milk should be compulsory throughout the UK. Menzies and Neill (2000) have recently published an extensive review of the literature regarding cattleto-cattle transmission of bovine TB. They state that the respiratory system is the main route by which infection occurs and spreads between cattle, and possibly, in contrast to Hancox, report that a single viable Mycobacterium bovis organism reaching the alveolar surface may be enough to establish infection. It is also noted that there can be a significant latent period following infection before excretion of the organism begins, followed by regular excretion of the tubercle bacilli in nasal mucus before excretion becomes intermittent, although the quantities of M. bovis may vary significantly between animals. A minimum of approximately 20% of cattle with tuberculous lesions may have M. bovis in their nasal secretions at any point in time. Under certain BCVA 2001 VOL 9 PART 1 circumstances that are as yet undetermined, a small proportion of these cattle may become effective disseminators of infection. Poor nutrition or persistent viral infections such as bovine viral diarrhoea virus and bovine immunodeficiency virus are postulated to increase the susceptibility of cattle to infection with M. bovis, although it is acknowledged that no studies have demonstrated this. While some may take issue with the conclusions drawn by Hancox with regard to the risk of badgerto-cattle transmission, all three of these papers should be of interest to those involved in the control and eradication of bovine TB. A paper by Scanlon and Quinn (2000) provides us with some useful information on the survival of Mycobacterium bovis in cattle slurry. They report that M. bovis can survive in slurry for up to 171 days. On the strength of this study it would seem that slurry has to be stored for 6 months before it can be considered safe. This is very useful information for those advising on the isolation and testing of cattle for TB before they enter a herd, producing a herd health plan to aid in the control of TB, or unfortunate enough to have to advise a client after a TB breakdown. BIOSECURITY Biosecurity is becoming an increasingly topical issue in relation to cattle production in the UK. While the term biosecurity means slightly different things to different people, there is general agreement that much could be done to improve herd health and productivity by implementing well designed 'biosecurity plans' that are proactive in preventing the introduction and spread of infectious diseases at a herd level. There have been three recent papers published in this area from the USA, the first Gillespie (2000) takes a very broad view of the subject and defines biosecurity as those cumulative steps taken to prevent transmission of pathogens or other harmful agents to individuals or populations of humans. This paper discusses various aspects of safeguarding the food chain including the prospect of having to guard against the threat of bioterrorism and biowarfare in the future! While these issues of national security are outside the scope of individual veterinary surgeons, the paper does underline the fact that with regard to zoonotic and food-borne disease, herd level biosecurity is an important step in safeguarding public health. As such it is likely to become an increasingly important aspect of quality assurance in the future. A paper by Wells (2000) looks specifically at biosecurity related to infectious diseases in US dairy operations, using Johne's disease as an example, and is perhaps closer to what most readers of this review 72

CATTLE PRACTICE would consider biosecurity to mean in relation to their clients' herds. The paper characterises risks related to the use of certain management practices and possible risk reduction within an infectious disease biosecurity programme. The biosecurity practices discussed focus on the prevention of introduction of pathogens to the herd, and estimates of risk associated with the introduction of different sources of cattle. In addition, biosecurity practices to limit the transmission of pathogens within an infected herd are discussed; with regard to Johne's disease these focus on sick cow management, calving area management and manure management. In conclusion the author states that it is important for each dairy enterprise to evaluate the risks for various hazards, and use this to design and implement the appropriate risk management plan, as biosecurity programmes are not one size fits all. They make the point that many of the biosecurity practices discussed in the paper have not been adopted on US dairy farms, indicating a risk of disease and opportunity for animal health improvement, the same would be true in the UK. The third paper on this subject (Sanderson et al. 2000) reports the results of an investigation into current biosecurity practices in beef cow-calf (suckler) operations in the US. The study found that cow-calf producers commonly engaged in management practices that increased the risk of introducing disease to their cattle, such as introducing cattle, failing to quarantine introduced cattle, and communal grazing. Furthermore, producers inconsistently adjusted their management practices for this increased risk, and did not always implement appropriate vaccination schedules or quarantine and test procedures to minimise the risks. It was concluded that veterinary involvement in education of producers regarding biosecurity risks and the development of rational and economic biosecurity plans was needed. There are substantial gains that could be made in herd health and profitability, as well as potential benefits to public health, if veterinary practitioners in the UK were more proactive in promoting biosecurity plans to their beef and dairy clients. BABESIOSIS A paper from Dublin (Sherlock et al. 2000) reviews the clinical assessment of cases of babesiosis and criterion used in determining whether a blood transfusion is indicated as part of therapy. The clinical and haematological findings in 163 cases of bovine babesiosis were examined. Mucous membranes were recorded as pink, pale, congested or jaundiced in 53%, 22%, 15% and 9.6% of cases respectively. Mucous membrane colour was not a reliable indicator of PCV status, as 45% of animals BCVA 2001 VOL 9 PART 1 with pink mucous membranes and 59% with congested mucous membranes were anaemic (PCV≤0.24 l/l). Animals with pipestem diarrhoea had significantly higher body temperatures than those that presented with either constipation or normal faeces, while animals with constipation had significantly lower body temperatures than those that presented with normal faeces. Blood transfusions were administered in 25.7% of cases. It was concluded that had a PCV≤0.15 l/l been used as the threshold for a decision to transfuse, the clinical signs most likely to indicate the need for a blood transfusion were pale or jaundiced mucous membranes, body temperature < 37.8°C (<100°F) and constipation. Clinical signs least likely to be associated with a PCV≤0.15 l/l were pink or congested mucous membranes, pipestem diarrhoea or normal faeces. However, there was no significant difference in case fatality rate in this study when animals with a PCV£0.15l/l that received a blood transfusion were compared with animals with a similarly low PCV that did not receive a transfusion. These findings highlight the difficulty in establishing definitive guidelines based solely on clinical signs, with respect to assessing the requirement for transfusion therapy in cattle suffering from babesiosis caused by Babesia divergens under Irish conditions. In view of the above discussions on biosecurity it is worth remembering that blood transfusions may transmit disease, for this reason wherever possible blood donors and recipients should at least be from the same herd! ACKNOWLEDGEMENTS The author would like to thank UK Vet Publications for permission to reproduce the Cattle News columns in Cattle Practice. REFERENCES Bergeron N., Fecteau G., Paré J., Martineau R., Villeneuve A. (2000) Vertical and horizontal transmissioin of Neospora caninum in dairy herds in Québec. Can. Vet. J. 41: 464-469. Brückmann A., Höck C., Linke K., Hennies M., Schallenberger E. (2000) Alterations of growth hormone, cortisol, luteinizing hormone, and insulin concentration in early-postnatal calves affected with diarrhea. Dom. Anim. Endo. 18: 187-197. Dyer R.M., Jenkins M.C., Kwok O.C.H., Douglas L.W., Dubey J.P. (2000) Serologic survey of Neospora caninum infection in a closed dairy cattle herd in Maryland: risk of serologic reactivity by production groups. Vet. Para. 90: 171-181. Eckersall P.D. (2000) Acute phase proteins as markers of infection and inflammation: monitoring animal health, animal welfare and food safety. Irish Vet. J. 53: 307-311. Fels-Klerx van der. H.J., Horst H.S., Dijkhuizen A.A. (2000) Risk factors for bovine respiratory disease in dairy youngstock in the Netherlands: the perception of experts. Livestock Prod. Sci. 66: 35-46. Galindo F., Broom D.M. (2000) The relationships between social behaviour of dairy cows and the occurrence of lameness in three herds. Res. in Vet. Sci. 69: 75-79. Gibbons-Burgener S.N., Kaneene J.B., Lloyd J.W., Erskine R.J. (2000) Influence of the milk and dairy quality assurance 73

CATTLE PRACTICE program on dairy farm drug management practices. J.A.V.M.A. 216: 1960-1964. Gillespie J.R. (2000) The underlying interrelated issues of biosecurity. J.A.V.M.A. 216: 662-664. Hancox M. (2000a) Cattle tuberculosis schemes: Control or eradication. Letters in Applied Microbiology 31: 87-93. Hancox M. (2000b) Cattle TB schemes: control or eradication - a critical reappraisal. Respiratory Medicine 94: 1007-1008. Mars M.H., Jong M.C.M. de., Maanen C van., Hage J.J., Oirschot J.T van. (2000) Airborne transmission of bovine herpesvirus 1 infections in calves under field conditions. Vet. Micro. 76: 1-13. Menzies F.D., Neill S.D. (2000) Cattle-to-cattle transmission of bovine tuberculosis. The Vet. J. 160: 92-106. Moore S., Gunn M., Walls D. (2000) A rapid and sensitive PCRbased diagnostic assay to detect bovine herpesvirus 1 in routine diagnostic submissions. Vet. Micro. 75: 145-153. Reenen C.G. van., Mars M.H., Leushuis, I.E., Rijsewijk, F.A.M., Oirschot, J.T. van., Blokhuis, H.J. (2000) Social BCVA 2001 VOL 9 PART 1 isolation may influence responsiveness to infection with bovine herpesvirus 1 in veal calves. Vet. Micro. 75: 135-143. Sanderson, M.W., Dargatz D.A. (2000) Risk factors for the high herd level calf morbidity risk from birth to weaning in beef herds in the USA. Prev. Vet. Med. 44: 97-106. Sanderson M.W., Dargatz D.A., Garry F.B. (2000) Biosecurity practices of beef cow-calf producers. J.A.V.M.A. 217: 185-189. Scanlon M., Quinn P.J. (2000) The survival of Mycobacterium bovis in sterilized cattle slurry and its relevance to the persistence of this pathogen in the environment. Irish Vet. J. 53: 412-415. Sherlock M., Healy A., Larkin H.A., Doherty M.L. (2000) Bovine babesiosis: Clinical assessment and transfusion therapy. Irish Vet. J. 53: 572-578. Weary D.M., Chua B. (2000) Effects of early separation on the dairy cow and calf 1. Separation at 6 h, 1 day and 4 days after birth. Applied An. Behaviour Sci 69: 177-188. Wells S.J. (2000) Biosecurity on dairy operations: Hazards and risks. J. Dairy Sci. 83: 2380-2386. 74

BCVA 2001 75 CATTLE PRACTICE VOL 9 PART 1 the three tests and to assess the value of measuring the specific gravity of colostrum on farm. In cattle the specific gravity of colostrum has been shown to be linearly related to immunoglobulin concentration (Fleenor et al 1980). From these results it can be seen that there was a good correlation between the ZST and the total protein (correlation coefficient 0.83) but a much poorer correlation between either of these two tests and IgG (0.479 and 0.449). An Investigation of On-Farm Measurement of Colostrum Quality and Comparison of Serological Tests for the Measurement of Colostral Immunoglobulin Transfer in Dairy Calves Carrington I.R., Hadrian Veterinary Group, Hexham, Northumberland, NE46 1HJ. In the late spring of 1994 a problem of high calf mortality was identified in a 170 cow dairy unit. Calf mortality for the previous 12 months was recorded at 34%, and the owner considered his problem to be caused by neonatal diarrhoea and pneumonia. A farm visit revealed an inability to wean before 12 weeks of age and poor growth rates in surviving calves. Inadequate colostrum intake was suspected. The beneficial effects of feeding colostrum to calves has been suspected for more than 80 years, and ensuring adequate and timely colostrum intake is a cornerstone of good calf husbandry. A variety of tests are available for assessing the efficacy of passive immunoglobulin transfer. 1) The zinc sulphate test (ZST). The method used was a modification of that described by McEwan. (McEwan et al 1970). This is a measure of the turbidity of serum after the addition of zinc sulphate measured against a standard solution; the results are then expressed in 'units'. 2) Serum protein by refractometer. 3) Radial immunodiffusion is usually regarded as the gold standard, but is relatively expensive and takes longer to perform than other tests (Blood et al). The test was carried out using the ICN Immunobiological Bovine IgG Kit, this uses the Fahey and McKelvey technique (Fahey et al 1965).The zinc sulphate test (ZST) and the measurement of serum protein by refractometer both offer a more rapid result and previous studies have shown a reliable correlation between these tests and radial immunodiffusion (Blood et al, Fahey et al 1965). Initially six clotted blood samples were taken from calves under one week of age; these were submitted for ZST estimation. All were considerably below the target of 20, one being only 1.6 units. It was decided to play closer attention to colostrum intake; calves were left with the cow to allow natural suckling and this was supplemented with oral dosing if necessary. During the next twelve months the effectiveness of the passive transfer of immunoglobulins to the calves was measured by testing serum from calves bled at less than seven days of age. In addition, specific gravity determination was carried out on colostrum samples from each cow, using a wine hydrometer. This was in an effort to gain a quantitative measurement, 'Colostrometers' (Fleenor et al 1980) are available commercially but these are generally small and read qualitatively. These readings afforded the opportunity to compare Table 1. Comparison of results of measuring colostrum uptake by ZST, serum refractometry and radial immunodiffusion on serum, related to n farm measurement of colostrum quality by specific gravity. Average of 89 samples taken. ZST and Refractometer 0 10 20 30 40 50 60 4567 ZST ZST v RID 0 10 20 30 40 50 60 0 10 1 20 ZST ZST (units) Refractometer Total Protein (g/l) RID IgG (g/l) Colostrometer Specific Gravity 23.2 5.8 16.2 1.04

CATTLE PRACTICE This apparent poor correlation was not observed in previous studies (McBeath 1970, Fisher et al 1976). It has been suggested that proteins other than immunoglobulins, such as Fibrinogen and Acute Phase Proteins are also measured by the ZST and refractometry methods and that this may lead to the poor correlations observed. The Author has been advised that these other proteins would not have significantly influenced the results (personal communication). Problems did arise with the on farm measurement of colostrum quality by hydrometer. The temperature of the colostrum had to be assumed to be constant and to this end readings were taken immediately after stripping the sample from the cow. During the process of sample collection however, a 'head' formed on the colostrum and the liquid had to be decanted into the measuring cylinder to take the measurement. This may have led to temperature fluctuations between samples. Fleenor and Stott (Fleenor 1980) considered specific gravities of colostrum lower than 1.035 to represent poor quality, readings between 1.036 and 1.046 to be moderate and values greater than 1.047 to be excellent. On this basis forty-two of the samples were classified as poor quality (estimated globulin level of<22mg/ml); thirty-seven samples were classed as moderate (estimated globulin level of 22- 50mg/ml) and ten as excellent (estimated globulin level of >50 mg/ml). Their paper however does not indicate at what temperature the colostrum was tested, but implies it was tested immediately after collection. McGuirk (McGuirk 1992) in her paper on colostrum quality and quantity suggests that readings should be made at 20C; lower temperatures over estimate immuno-globulin concentration while warmer temperatures under estimate the true value. McGuirk's paper emphasizes that the single most important factor in the acquisition of passive BCVA 2001 VOL 9 PART 1 immunity is the volume of colostrum ingested. Diligent administration of large amounts of colostrum will to some extent overcome any shortcoming in colostral quality. The paper also states that calves should receive between 200-300 grams of immunoglobulin mass before 12 hours of age or up to 400grams by 24 hours of age to ensure successful passive transfer. Extrapolating this data and that of Fleenor and Stott: in the case of colostrum with specific gravity of 1.030 (equivalent to 9mg of immunoglobulin per ml), 4 litres of colostrum would provide only 36 grams of immunoglobulin. This would seem to question the accepted wisdom of ensuring a minimum of 2 litres of colostrum for a newborn calf and suggest this figure should be revised upward. Yet calves, which received such colostrum, showed ZST values of 29.0, 12, 21.3, 2.4, 35.5, 27.4, 29.6 and 16.1. In conclusion the results confirm a good correlation between ZST and refractometry and suggest that there is little benefit in using the more expensive and time consuming radial immunodiffusion. Copper sulphate solution has also been used in a trial for an on farm test of the immunoglobulin status of calves (Munro 1996). Unfortunately its use was found to be unsatisfactory. In my experience, the determination of colostral specific gravity did not appear to be of any value in assessing the likelihood of effective immunoglobulin transfer. I would like to acknowledge the help of Mr Derek Challoner and the Veterinary Laboratory Agency, Newcastle upon Tyne in preparing this paper. REFERENCES Blood, Henderson, Radostits. Veterinary Medicine - Eighth edition. Bailliere Tindall Fahey J.L., McKelvey E.M., (1965), J. Immunology, 94: 84 Fisher & Martinez Vet Rec (1976) 9831 Fleenor & Stott. Journal of Dairy Science (1980) 63: 973 McBeath. Vet Rec (1970) 88: 266 McEwan A.D.,Fisher E.W., Selman I.E., Penhale W.J., (1970). Clin. Chim. Acta. 27: 155 McGuirk. ,World Buiatrics Congress (1992) Vol. 2: 162-167 Munro., Cattle Practice 1996 Vol. 4:2 Page 167 76 ZST and Colostrimeter 20 40 60 ZST Refractometer v RID 0 1 2 3 4 5 6 7 8 Refractometer

BCVA 2001 77 CATTLE PRACTICE VOL 9 PART 1 On examination 2 days later, the heifer's rectal temperature had reduced to 102.5 and the conjunctivitis and lachrimal discharge had greatly reduced. She remained anorexic and dull. The mouth and nasal lesions had worsened considerably with necrosis and sloughing of all visible oral mucous membranes, the development of a severe and malodorous purulent nasal discharge and necrosis of the muzzle area. The lymph nodes had further enlarged, although no further skin lesions could be found apart from the development of a coronitis and evidence of interdigital dermatitis. Despite a very guarded prognosis, the owner was reluctant to give up on the animal until blood results had come through. A further injection of 'Nuflor' was given as before, and 'Zenecarp' dispensed for injection the following day. The owner was also advised to inject the heifer daily with 20 mls of 'Pen and Strep' (Norbrook Laboratories Ltd., UK) by intramuscular injection and to drench fluids as well as a pulp nut and 'Pro-Rumen' (Vetoquinol Ltd., UK) broth made up with warm water. Serum analysis for BVD antigen and antibody using ELISA revealed serum negative for BVD virus and positive for BVD antibody. This ruled out Mucosal Disease as a cause of the clinical findings. With the weekend approaching and nasties such as Vesicular stomatitis and Foot-and-Mouth bearing down upon me, a phone call to Geoff Pritchard, FRCVS was much needed. No evidence of illness in other cattle or sheep on the farm allowed a presumptive diagnosis of MCF (and a sigh of relief for myself at not having to entertain the DVO that weekend!). The heifer's condition had plateaued and the owner was keen to have a diagnosis despite the extremely grave outlook. Analysis for MCF using an immunofluorescent antibody test and PCR on serum and buffy coat respectively, was undertaken. The serum tested positive for antibodies for MCF which confirmed disease. The buffy coat tested negative for virus. Blood sample shuffling and testing with the odd postal go-slow thrown in for good measure, had taken up nearly 14 days. The owner now reported the heifer drinking and he was keen to keep her going. On the 16th day she actually began eating softened feed of her own accord. The heifer went from strength to strength rapidly gaining her quickly lost condition - I patted the owner on the back for his inexhaustible stockmanship ... and he refused to pay for the blood tests! Unusual Manifestations of Malignant Catarrhal Fever (BVD) in a Yearling Heifer Rawdon T.G., Manor Veterinary Centre,10 Manor Road, Chatham, Kent, ME4 6AG. INTRODUCTION Bovine Malignant Catarrhal fever (MCF) occurs in two similar forms worldwide. In Africa, the Wildebeest associated form results from infection with alcephaline herpes virus 1 and 2. In the rest of the world an as yet unidentified sheep associated herpes virus, possibly ovine herpes virus-2 appears to be responsible for a sheep associated form. Both the wildebeest associated and sheep-associated forms cause similar clinical disease, most notably fever, a mucopurulent nasal discharge, oral erosions, severe centripetally progressive keratoconjunctivitis and lymphadenopathy (Blood and others, 1990; Smith, 1990). I was called early one morning to see a prize winning show heifer belonging to an extremely good stockman running a mixed family farming enterprise with a sheep flock, a suckler herd and small feedlot as well as an arable side. The 18 month old Belgian Blue cross Blonde d'Aquitane heifer was in peak condition, being ready for the show circuit. The owner that morning was very concerned as he thought she was coming down with a severe case of Infectious Bovine Rhinotracheitis (IBR). HISTORY AND CLINICAL FINDINGS AND TREATMENT On questioning, the heifer was found to have been vaccinated 9 months earlier against IBR (Tracherine, Pfizer Ltd., UK), when she first arrived on the farm. Examination revealed a very dull animal, a rectal temperature of 103.5°F, bilateral conjunctivitis with a clear lachrimal discharge, inflammation and evidence of ulceration of the tongue, gingiva and hard palate, excess ropey salivation and a rhinitis with a clear-tomucopurulent nasal discharge. Also evident were discrete teat, perineal and skin ulcerations and superficial lymphadenopathy especially evident in the prescapular lymph nodes. The heifer was treated with 9 grams florfenicol (Nuflor, Schering-Plough Animal Health, UK) intramuscularly and 750 mg carprofen ( Zenecarp, now Rimadyl, Pfizer Ltd., UK) intravenously. A blood sample was taken and sent to VLA for Bovine Viral Diarrhoea (BVD) virus analysis. The owner was warned that either BVD/Mucosal Disease or MCF was at work with an extremely grave outlook. It was recommended that the heifer be kept in a separate stall and a reexamination was advised for 48 hours.

CATTLE PRACTICE Six weeks elapsed when the owner reported sudden onset blindness. I returned to investigate and found that she had developed a severe bilateral keratitis rendering her virtually blind. There were no other signs of disease and she remained in excellent body condition. Topical antibiotic (Cepravin Eye Ointment, Schering-Plough Animal Health, UK) and subconjunctival steroid (Voren Suspension, Boehringer Ingelheim Ltd., UK) injections failed to alleviate the keratitis. About two weeks later, she was slaughtered. This was undertaken despite her coping well with the disability, because the owner was under the fear that full blown clinical disease may once again rear its head. DISCUSSION It is generally assumed that most or all cattle with MCF die after a short clinical illness, so much so that many veterinarians would amend their clinical diagnosis on recovery of an animal that initially presented with symptoms typical of MCF (O'Toole and others 1997., Smith, 1990). This view has been upheld until recently because recovered animals are unlikely to be examined post-mortem and because reliable diagnostic assays in the live animal have only recently been developed. Finding only antibodies to MCF with no antigen presence, yet with the clinical findings described and the absence of BVD antigen, it can be assumed that this heifer succumbed to sheep-associated MCF (G. Pritchard, pers. communication). This case differed from many described cases in a number of ways. There was no corneal opacity in the initial disease course - this only became apparent with recrudescence 6 weeks later. A centripetally progressive keratitis is a key feature in the clinical course of MCF (Blood and others, 1990). No diarrhoea and only a short-lived and very mild pyrexia were evident in this heifer. A persistent pyrexia is considered standard and the presence of diarrhoea a common feature of the clinical course of MCF (Collery and Foley, 1996). The most notable difference of the disease course in this heifer was her recovery from the acute phase. BCVA 2001 VOL 9 PART 1 A recent American study into 11 cases of sheepassociated MCF that survived for between 39 and over 800 days on four farms in Wyoming, indicated a survival rate of between 30 and 50 percent (O'Toole and others, 1997). This is in contradiction with popular opinion. In the described American cases, the most distinctive clinical feature in recovered animals was the presence of persistent bilateral leucomata. These lesions correspond to oedematous thickening within the substantia propria of the cornea. Other ocular lesions included unilateral anterior synechiae developing secondarily to perforating corneal ulceration and corneal melanosis as a result of migration of limbal melanocytes. The reason the described heifer showed no apparent corneal lesions in the acute phase of disease may have resulted from the use of a potent NSAID given intravenously at the first visit. My first visit I would judge to have been very early on in the course of disease as the farm has an extremely high standard of stockmanship and disease surveillance. So too, the failure to develop persistent pyrexia may have had its origins in the use of potent anti-inflammatory and antibiotic combinations. MCF manifest in this heifer differs from textbook descriptions of the disease and has some similarities to cases described in Wyoming. This emphasises the findings of O'Toole and coworkers where they concluded that the clinical spectrum of sheep-associated MCF may be wider than currently assumed. REFERENCES Blood D.C., Radostits O.M., Arundel J.H. and Gay C.C. (1990). Bovine malignant catarrh. In Veterinary Medicine. Blood D.C. and Radostits O.M. Editors. Bailliere Tindall, London. 841- 845. Collery P. and Foley A. (1996). An outbreak of malignant catarrhal fever in cattle in the Republic of Ireland. Veterinary Record 139: 16-17. O'Toole D.O., Li H., Miller D., Williams W.R. and Crawford T.B. (1997). Chronic and recovered cases of sheep-associated malignant catarrhal fever in cattle. Veterinary record, 140: 519- 524. Smith B.P. (1990) Malignant Catarrhal Fever. In Large Animal Internal Medicine. Smith B.P. Editor. The C.V. Mosby Company, St. Louis, 737-740. 78

BCVA 2001 79 CATTLE PRACTICE VOL 9 PART 1 Evidence of an active immune response (seroconversion) to the organism in the TTW was a specified rise in titer between paired sera. Falsenegative results, i.e. failure to seroconvert to the organism isolated in the TTW, were seen in 8/9 (89%) calves with bovine virus diarrhea virus in their TTW, 43/75 (57%) calves with Mycoplasma sp. in their TTW, 20/53 (38%) calves with Pasteurella multocida, 4/16 (25%) calves with Pasteurella haemolytica and 5/13 (38%) calves with Haemiophilus somnus isolates in their TTW. We do not recommend reliance on paired-serological testing to identify the respiratory pathogens present in the respiratory tract of clinically pneumonic dairy calves less than 3 months of age. Association of Seroconversion with Isolation of Agents in Transtracheal Wash Fluids Collected from Pneumonic Calves Less than Three Months of Age Bovine Practitioner May 2000 ABSTRACT The objective of this study was to investigate the potential association between seroconversion to organisms important in respiratory disease and isolation from transtracheal wash fluids (TTW) collected from pneumonic dairy calves less than 3 months of age. These calves had naturally acquired infections and represented 18 commercial dairy farms. Each calf had at least one respiratory pathogen cultured from the TTW, which was carried out at the time of clinical diagnosis. Blood samples were first collected at the time of diagnosis and a second sample was collected 3 weeks later. Most calves had evidence of maternal antibodies (at 2 days of age) to the same pathogens isolated from the TTW at the time of respiratory diseases diagnosis. Choosing the Right Cut Off Level of Milk Progesterone to Determine Pregnancy Status of Dairy Cows on Day 21 PostBreeding ABSTRACT A field study was conducted between February and November 1995 in three Holstein dairy herds (193 inseminations) to determine the overall accuracy and usefulness of the skim milk progesterone pregnancy test on day 21 post-breeding and to examine the effects of using different cut off values and conception rates on predictive value of this pregnancy test. Results of the milk progesterone test were compared to pregnancy diagnosis after 25 days post-breeding using transrectal ultrasonography and palpation as a non-perfect gold standard. The conception rate of the study population based on transrectal palpation was 42%. The relative sensitivity, specificity, positive and negative predictive values of the milk progesterone test at a cut off level of 1ng/ml were 90%, 67% 66% and 90%, respectively. These results confirm that in a herd population with a conception rate of 42%, the milk progesterone test is not a good predictor of pregnancy because the proportion of false positive results was high at 19% (37/193). The capacity of the test to detect open cows is acceptable with an overall proportion of false negative tests of 4% (8/193). Because 8 out of 83 cows tested negative were subsequently diagnosed pregnant by transrectal examinations, this milk progesterone test would be expected to result in a 10% probability of misdiagnosing pregnant cows as non-pregnant. If this test was applied in the field, the 1ng/ml cut off value would be expected to result in optimal probabilities (>90%) in predicting non-pregnancy in dairy herds with a conception rate of less than 50%. Herds with a conception rate over 50% would not be expected to benefit as much from the test since the predictive value of a negative test is less than 90%. Finally, considering that a false negative diagnosis is more costly than a false positive, the optimal cut off value was also calculated at a three to one ration in favour of finding fewer false negatives. In this case, the optimal cut off value for the herd with a 42% conception rate was 1.2 ng/ml. This study shows that the usefulness of the progesterone test relies on assessing the right cut off level for the milk progesterone pregnancy test which relies not only on the measurement itself but also on the expected conception rate and the ratio between false negative and false positive test results. Bovine Practitioner May 2000

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 between higher rates of mastitis in cows housed in straw yards as opposed to cubicles and also between higher rates of lameness in cows housed in cubicles as opposed to yards (P<0.015). However, there were farms with low rates of mastitis in cows kept in straw yards and low rates of lameness in cows kept in cubicles. Larger herds tended to have more problems with lameness and higher bulk milk somatic cell counts (BMSCC). There was a positive association between BMSCC and mastitis rate. 80 Data derived from 340 dairy herds, mainly in Southern England, between April 1998 and March 1999, showed that the average total culling rate was 22.1% with 5.6% for infertility, 3.6% for mastitis, 1.7% for lameness, 2.0% for poor milk yield, 3.7% for age and 5.5% for miscellaneous reasons which included death. The average annual rate of assisted calvings was 8.7%, of injury 0.9%, digestive disease 1.3%, ketosis 0.4%, hypomagnesaemia 0.7%, hypocalcaemia 5.3%, mastitis 36.6% and lameness 23.7%. There was a significant association (P<0.001) Disposal and Disease Rates in 340 British Dairy Herds Bovine Practitioner May 2000 Evaluation of the Early Conception Factor (ECF™) Dip Stick Test in Dairy Cows Between Days 11 and 15 Post-Breeding Bovine Practitioner May 2000 ABSTRACT A field study was conducted between February and November 1995 using 139 Holstein cows to determine the accuracy and the usefulness of the ECFä Dip Stick Test performed between days 11 and 15 post-breeding. Results of the ECFä tests were compared to pregnancy diagnosis after 25 days postbreeding using ultrasonography and transrectal palpation. The apparent conception rate of the study population based on transrectal palpation was 38%. The ECFä test sensitivity, specificity, positive and negative predictive values were 81%, 26%, 40% and 69%, respectively. The Kappa value (0.06, 95% CI - 0.19 to 0.30) demonstrated no agreement between the ECFä test and the final pregnancy status of dairy cows. These results would indicate that the ECFä test is not a good predictor of pregnancy because the proportion of false positive results was high at 46% (64/139). Furthermore, the accuracy of the test to detect open cows is not acceptable with the high proportion of false negative tests of 31% (10/32). This finding would indicate that 19% (10/53) of the cows diagnosed pregnant rectally were misdiagnosed as non-pregnant by the ECFä test. Finally, many factors such as the incubation time, the personal assessment of the test reaction and the source of light can also affect the ECFä test reading. Based on the current technology the authors would not recommend the use of the ECFä test to help dairy producers reduce non-productive days. Bovine Practitioner May 2000 ABSTRACT Hematologic data from 45 adult Holstein cows with coliform mastitis and systemic clinical signs were studied retrospectively. They developed panleukopenia that resolved over several days, first through an increase in immature forms and later be an increase in mature neutrophils. Neutropenia lasted three days in most cows. The majority of cows in early lactation did not develop neutropenia for an unknown reason. Cows with fatal disease could not be distinguished based on hematologic analysis, because most died early in the disease, while both surviving and non-surviving cows still had panleukopenia. Cows with coliform bacteremia had prolonged neutropenia and higher metamyelocyte and myelocyte counts during the regenerative phase. These findings suggest that hematologic analysis during the regenerative phase may be useful to identify cows with bacteremia for more aggressive treatment. Hematologic Abnormalities Over Five Days in Cows with Acute Escherichia coli Mastitis

CATTLE PRACTICE ABSTRACT Immunohistochemical (IHC) testing of skin biopsies (ear notch samples) is a method to identify cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV). Skin biopsies were taken from 90 calves upon arrival (day 0) at a feedlot and on days 14, 28 and 42 following arrival. Calves were vaccinated with modified live virus (MLV) BVDV vaccine on days 1 and 14 following arrival. Additional samples were taken from 50 of the calves between days 1 and 10 when they were treated for bovine respiratory disease. Immunohistochemical testing for BVDV antigen was performed on all samples. One calf was positive for BVDV antigen by IHC BCVA 2001 VOL 9 PART 1 techniques on 5 skin biopsies. This calf was also positive by virus isolation (VI) on the buffy coat of a blood sample taken on day 42 following arrival. All samples from the remaining calves were negative when tested with the IHC method. Other tests, VI and polymerase chain reaction (PCR) used to identify PI cattle may give positive results in cattle recently vaccinated with MLV BVDV vaccine. This study suggests that IHC testing of skin biopsies may be advantageous over other tests to identify PI cattle recently vaccinated with MLV BVDV. Further studies are needed to better define the utility of this testing method for cattle that are PI with BVDV. 81 Ultrasound Guided Percutaneous Lung Biopsy in Sheep Bovine Practitioner May 2000 ABSTRACT Lung biopsies were taken through the ninth intercostal space on the two sides of the thorax of 10 clinically healthy sheep, using a Tru-Cut needle on one side and the Bard Biopty System on the other. Nine of the 10 sheep remained clinically healthy but one coughed transiently and had a mild bloody discharge from the right nostril immediately after the biopsy. The sheep were slaughtered 10 days later and the lungs and pleura were examined macroscopically, there were either no lesions or only small scars visable at the sites of the biopsies. However, welldeveloped subpleural nodules due to parasites were observed in some of the lungs, There were no adhesions between the costal and pulmonary pleurae. Of the 20 biopsy specimens, 18 were ideal for histological examination and none of them was histologically normal. Mild interstitial pneumonia was diagnosed in 15 specimens, chronic bronchiolitis in 9 specimens and hyperplasia of smooth muscle or connective tissue in 17. Johne's Disease in Sheep and Goats Bovine Practitioner May 2000 ABSTRACT Johne's Disease or paratuberculosis is a chronic enteric disease of ruminants and has a worldwide distribution. Economic losses from the disease can be measured in terms of reduced production as well as culled animals. Unlike cattle, in which the disease has been more extensively studied, chronic diarrhoea is not a consistent feature of Johne's disease in sheep and goats, the predominant clinical sign in these smaller ruminants is weight loss over a period of weeks or months, Johne's disease is caused by the bacterium Mycobacterium avium subspecies paratuberculosis. Sheep strains generally fail to grow, or grow poorly, on routine culture media which support luxurious growth of the organism isolated from cattle. Goat strains tend to be more akin to cattle strains. A Preliminary Evaluation of the Effect of Vaccination with Modified Live Bovine Viral Diarrhea Virus (BVDV) on Detection of BVDV Antigen in Skin Biopsies Using Immunohistochemical Methods Bovine Practitioner May 2000

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 82 Case Report - Nephrectomy for the Treatment of Ectopic Ureter in a Holstein Heifer Calf Bovine Practitioner May 2000 ABSTRACT A two week old Holstein heifer was examined for dribbling of urine and scalding of the perineum since birth. The history and clinical findings were suggestive of an ectopic ureter. Contrast radiography, endoscopic examination of the vagina and urinary bladder and ultrasonography were supportive of a left ectopic ureter. A definitive diagnosis of a left extopic ureter and hydronephrosis was made during abdominal exploratory surgery. The left kidney and ureter were removed. The calf recovered without complications or urinary incontinence. Pasture Deworming and /or Subsequent Feedlot Deworming with Fenbendazole. I. Effects on Grazing Performance, Feedlot Performance and Carcass Traits of Yearling Steers (Dedicated to the memory of Dr. Jerry R. Rains, who died on 6th December 1999) Bovine Practitioner May 2000 ABSTRACT Seven hundred and thirty-four steers (629lb, 286kg) were utilised during a 118 day grazing period, after which six hundred and forty were placed in a feedlot for finishing (average of 121 days, range of 111-133 days) to measure the main effects and interactions of two pasture deworming treatments (negative control, strategically dewormed with fenbendazole) and two feedlot deworming treatments (negative control, dewormed with fenbendazole) on grazing performance, feedlot performance, carcass traits and production economics for yearling steers. Strategic deworming with fenbendazole (FBZ) during the grazing phase increased pasture gain by 48lb (22kg P=.014) compared to control steers. Final weight, daily gain, dry matter intake and feed/gain ratios in the feedlot were affected by pasture treatment x feedlot treatment interactions, showing that while feedlot deworming improved performance of steers in all treatments, it had a much greater effect on performance of pasture control steers. On a live basis (deads not included), deworming with FBZ in the feedlot improved daily gain of pasture control steers by 13.4% (P<.001), compared with a 4.2% improvement (P = .01) for steers that had been strategically dewormed on pasture. Similarly, feedlot deworming improved feed/gain 4.65% (P <.0003) for pasture control steers, vs. a non-significant improvement of 0.4% (P = .74) for steers, that had been strategically dewormed. On a carcass-adjusted basis, feedlot deworming of strategically dewormed steers increased daily gain 6.8% (P<.0001) and feed/gain by 2.9% (P = .07). Feedlot deworming of pasture control steers increased daily dry matter intake (DDMI) by 7.8% (P<.0001) compared to no feedlot deworming while feedlot deworming increased DDMI by 3.2% (P<.005) in the same comparison for strategically dewormed steers. Carcass traits were affected similarly. Dressing percentage was increased by both strategic deworming on pasture (P = .08) and feedlot deworming with fenbendazole (P <.0001). Feedlot deworming of pasture control steers increased carcass weight by 49lb (22kg; P<.0001)), while feedlot deworming of steers that were strategically dewormed on pasture increased carcass weight 21lb (9.5kg; P<.002). The percentage of choice carcasses was lower (P<.001) and the percentage of select carcasses was higher (P<.001) for the pasture control feedlot control steers compared to the other treatment groups. Strategic deworming during grazing resulted in a net benefit of $33.75 per head, had steers been sold at the end of the grazing phase. For the complete grazing/finishing system, feedlot deworming of previously non-dewormed steers with FBZ produced a net benefit of $30.61 per head on a carcass adjusted basis, while feedlot deworming of strategically dewormed steers produced a net benefit of $11.07. Under the conditions of this study there were clear performance and economic benefits to strategically deworming grazing steers with FBZ on pasture and to deworming yearling steers with FBZ that were entering the feedlot from summer pasture.

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 83 Diagnosis of Lyme Disease in Two Cows by the Detection of Borrelia burgdorferi DNA Bovine Practitioner May 2000 ABSTRACT Two cows from different herds in a district of Switzerland known to harbour ixodid ticks had erythematous lesions on the hairless skin of the udder, were in poor general condition with a poor appetite and decreased milk production and had a stiff gait and swollen joints. Borrelia burgdorferi sensu strictu DNA was detected in samples of synovial fluid and milk from one of the cows and Borrelia afzelii DNA was detected in synovial fluid from the other by means of a real time PCR Pasture Deworming and/or Subsequent Feedlot Deworming with Fenbendazole. II. Effects on Abomasal Worm Counts and Abomasal Pathology of Yearling Steers Bovine Practitioner May 2000 ABSTRACT Seven hundred and thirty four steers (629lb, 286kg) were utilised during a 118 day grazing period, after which 640 were placed in a feedlot for finishing (average of 121 days, range of 111-133 days) to measure the main effects and interactions of two pasture deworming treatments (negative control, strategically dewormed with fenbendazole) and two feedlot deworming treatments (negative control, dewormed with fenbendazole) on faecal egg counts, abomasal worm counts and abomasal pathology. The companion paper in this series discussed the effect of deworming treatments on animal performance, carcass traits and production economics. Seven to ten abomasa from steers on each of the four pasture-feedlot treatments (pasture control, feedlot control; pasture control-dewormed in the feedlot, strategically dewormed on pasture feedlot control, strategically dewormed on pasturedewormed in the feedlot) were selected at slaughter to determine total worm counts and to evaluate gross pathology and histopathology of the abomasal mucosa. Pasture deworming with fenbendazole (FBZ) in a strategic progrmme on days 0, 28 and 56 reduced (P<.01) adult and L4 and EL4 larval stages of Ostertagia ostertagi and adult and L4 stages of Trichostrongylus axei (P<.03) residing in the abomasum at slaughter. Feedlot deworming with FBZ reduced (P<.05) L4 and EL4 stages of Ostertagia ostertagi and adult and L4 stages of Trichostrongylus axei. An interaction (P <.05) between pasture deworming treatment and feedlot deworming treatment showed that pasture deworming has a significant effect on reducing the number of Trichostrongylus adult parasites, which was not further reduced by feedlot deworming. Strategic pasture deworming with FBZ followed by FBZ administration at the beginning of the finishing period reduced total Ostertagia ostertagi, Trichostrongylus axei and Haemonchus adult and larval stages by 99.13% compared to untreated controls. There was no relationship between faecal egg counts and total worm counts. Gross pathology data showed that strategic deworming on pasture reduced (P = .02 the mean abomasal lesion score at slaughter, An interaction (P <.01) between pasture treatment and feedlot treatment showed that feedlot deworming of pasture control steers reduced mean histopathology score, while feedlot deworming of steers strategically dewormed on pasture had no impact. Distribution of histopathology scores showed that strategic deworming on pasture resulted in more steers (P <.03; Chi-square statistic) with no histpathological changes to the abomasal mucosa and fewer steers with higher histopathology scores.

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 84 Efficacy of Two Non-antibiotic Therapies, Oxytocin and Topical Liniment, Against Bovine Staphylococcal Mastitis Bovine Practitioner May 2000 ABSTRACT Eight cows were challenged by a single quarter intramammary infusion of a relatively low-virulence strain of Staphylococcus aureus on four occasions five weeks apart and after each challenge, each cow received one of four treatments, according to a duplicated Latin-square design. The treatments were massage alone (negative control), massage with a proprietary liniment, oxytocin and a single course of a proprietary intramammary antibiotic. The massage treatments were applied at every milking for three weeks, oxytocin was given for one week and the antibiotic was given after three successive milkings. Milk samples were collected immediately before and for three weeks after each challenge and a scoring system was used to quantify the presence of bacteria during the whole of the period. None of the treatments completely eliminated bacteria from all the cows. Relative to the negative control, the liniment had no significant effect, but both oxytocin and the antibiotic reduced the numbers of bacteria significantly and did not differ significantly in efficacy. Effect of Castration on Weight Gain of Beef Calves Bovine Practitioner May 2000 ABSTRACT Many management practices can be utilised to maximise weight and increase value of calves at weaning. Combining the two management practices of castration and implanting male calves allows producers to maximise weaning weights and avoid discounts for intact males. Crossbred bull calves were randomly assigned at birth to one of three treatment groups:- castrated (n = 22) banded (n = 18) left intact (n = 20). Calves that were castrated or banded within 24 hours after birth received a zeranol implant at that time. Calves in the intact group were castrated at 150 days of age and then implanted and the calves in the other two treatment groups were re-implanted at that time. There were no differences in weaning weight, average daily gain (ADG) or weight per day of age between the three treatment groups. Castrating calves shortly after birth reduces stress on the animal compared to castration at a older age (day 150 to weaning). Also, early castration may be more acceptable as an animal welfare issue. Combining castration and implanting allows producers to maximise weaning weight of calves as well as reducing the stress of castration at an older age. Case Report - Phosphine Gas Detected in the Rumen Content of Dead Calves Bovine Practitioner May 2000 ABSTRACT One hundred and fifty eight calves were fed whole corn containing aluminium phosphide tablets added to it the previous day. Twenty four hours later, 4 calves were found dead at the feed trough and 15-20 others were sick. The only significant findings at necropsy were lung lesions caused by previously diagnosed pneumonia. A strong odour resembling garlic or rotten fish was noted in the rumen of all dead calves. The owners indicated that they noticed the same odour when they fed the corn. Rumen content was placed in bags inside a sealed glass jar and sent to the Oklahoma Animal Disease Diagnostic Laboratory for analysis. Toxic phosphine gas was detected in the rumen content of necropsied cattle.

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 85 Case Study - Use of Compounded Antibiotics for Treatment of Mastitis Bovine Practitioner May 2000 ABSTRACT Extra label treatment of mastitis in dairy cows may be of questionable efficacy and legality. This study examines the extra label use of an antibiotic mixture compounded by a veterinary clinic to treat cows for mastitis on three farms. The mixture contained penicillin, spectinomycin and dexamethasone. The literature and regulations regarding use of each of these drugs for treatment of mastitis are discussed. The requirements established by the Animal Medicinal Drug Use Clarification Act (AMDUCA) were not met. The objective of this report is to increase awareness of risks involved in extra label use of antibiotics. Adulteration of the compounded product and potential for drug residues in foods from animal origin, are of particular concern. Effect of Three Programmes for the Treatment of Endometritis on the Reproductive Performance of a Dairy Herd Bovine Practitioner May 2000 ABSTRACT Three management programmes to improve the reproductive performance of a dairy herd were compared in a prospective controlled field study on one commercial farm. A total of 542 cows were examined for endometritis 22 to 28 days postpartum and assigned to one of three treatment groups. In Group 1 the cows with signs of endometritis were treated with an intrauterine infusion of 100ml of a 2% polycondensated m-cresolsulphuric acid formaldehyde solution. In Group 2 the cows with signs of endometritis were treated with an intrauterine infusion of 125ml of a 20% eucalyptus compositum solution. In Group 3 all the cows were injected intramuscularly with 0.75mg of tiaprost, an analogue of prostaglandin F2α (PGF2α) at two week intervals, starting on day 43, until they were inseminated. 34% of the cows showed signs of endometritis. In Group 3, oestrus detection efficiency was significantly higher than in Groups 1 and 2 (P<0.05), the interval to first service was shorter and the cows had fewer days open than the cows in Groups 1 and 2 (P<0.05). The results indicate that management programmes based on the strategic use of PGF2α are an effective alternative to traditional programmes based on rectal palpations and intrauterine infusions to control endometritis at a herd level.

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 86

BCVA 2001 87 CATTLE PRACTICE VOL 9 PART 1 about 20 feet in range. While moving away from the bull's flight zone, you should watch the bull at all times until you get to a fence, crawl space, or other safe retreat. Turning and running invites being chased. Not as likely, but the same can be said for aggressive fresh cows with their newborn calves as they too can attack and maul. Understand postures, threats There are certain major behavioural activities related to bulls. These are threat displays, challenges, territorial activities, female seeking and directing (nudging) and female tending. These activities tend to flow from one to another, Threat displays are a broadside view. This posture is observed when a person or another bull invades its flight zone. The threat display of the bull puts him in a physiological state of fight or flight. The threat display often begins with a broadside view with back arched to show the greatest profile, followed by the head down, sometimes shaking the head rapidly from side to side, protrusion of the eyeballs and erection of the hair along the back. The direct threat is head-on with head lowered and shoulders hunched and neck curved to the side toward the potential object of the aggression. Pawing with the forefeet, sending dirt flying behind or over the back, as well as rubbing or horning the ground are often components of the threat display. If, in response to the threat display, the recipient animal advances with head down in a fight mode, a short fight with butting of horns or heads ensues. If the recipient of the threat has been previously subdued by the animal, he will likely withdraw with no further interaction. While a bull is showing a threat display, if an opponent such as another bull (or person) withdraws to about 20 feet, the encounter will subside and the bull will turn away. If not, the bull will circle another bull or animal, drop into the cinch (flank) body position, or start with head-to-head or head-to-body pushing. At the first sign of any of the above behaviours, humans should avoid the bull and exit rapidly, hopefully via a predetermined route. With the advent of artificial insemination, the bull initially left many dairy farms. With poor oestrus detection and difficult breeding cows, the yearling bull has made a comeback as a "clean-up" bull. While Why and How to Read a Cow or Bull Knowing Behaviour Patterns, Especially of Bulls, may Help Reduce Injuries and Might Possibly Save Your Life. Reading Behaviour Can Also Help You Improve Care Hoards Dairyman November 2000 ABSTRACT Automation, considered by some to be detrimental to the husbandry and welfare of animals in intensive units, needs to be reconsidered. The time saved, together with reduced work and drudgery, should release workers for more human or animal interactions, thus allowing better care. Yet, there are many instances where farm staff come into one-onone contact with animals. Are they prepared? For as long as cows have been milked, there has been the art of cow care that results in more milk from healthier, contented cows. It has been recognised that the dairy cow's productivity can be adversely affected by discomfort or maltreatment. Alert handlers have the perception and ability to read body language in animals. For example, healthy calves, cows and bulls will exhibit a good stretch after they get up, then relax to a normal posture. Yet, higher rates of standing, often times with an arched back and with their head and ears lowered, is taken as a sign of discomfort or discontent in studies of cow and calf confinement. Cattle under duress show signs by bellowing, butting or kicking. Behavioural indicators like these are always useful signs that the environment needs to be improved. In some cases, the way animals behave is the only clue that stress is present. You can get clues to a cow's mood and condition by observing the tail. When the tail is hanging straight down, the cow is relaxed, grazing or walking, but when the tail is tucked between the cows legs, it means the animal is cold, sick or frightened. During mating, threat or investigation, the tail hangs away from the body. When galloping, the tail is held straight out and a kink can be observed when the animal is in a bucking, playful mood. Dealing with bulls By virtue of their size and disposition, bulls may be considered as one of the most dangerous of domestic animals. Farm procedures should be designed to protect human safety and to provide for bull welfare. Everyone who comes into contact with bulls should recognise the various body postures of threat and aggression. This is the only way a person can stay mentally and physically ahead of the bull. If cornered by a bull, it is best not to move too fast, but to back away from the bull's flight zone which is

CATTLE PRACTICE observing cows in larger herds in the Southwest U.S., I found as many as seven yearling bulls in a group. Rightfully so, at the first sign of meanness, a bull was sent on a one-way trip to the butcher. Many people lack the background, attitude and precaution of dealing with dangerous bulls and fresh cows, therefore, additional training on bull/cow behaviour is needed. It is wise to respect and be wary of all bulls, especially dairy bulls, as they are not to be trusted. Each bull is different and any bull is potentially dangerous. He may seem to be tame, but, on any given day, he may turn and severely injure or perhaps kill a person, young or old, inexperienced or experienced. Bulls become defensive when a cow is in heat and needs to be removed from "his" group or moved with the group to the holding pen for milking. Never handle the bull alone and never turn your back on a bull. To move cattle or to appear larger and to protect oneself, carry a cane, stick, handle, plastic pole with flap, or a baseball bat. For further information about bull behaviour and handler safety, refer to the book by Albright and Arave "The Behaviour of Cattle" CAB International 1997 or many of the older dairy textbooks. In addition to bulls, you must be careful around certain steers, heifers and recently calved cows protecting their calves. Some animals are different and do not follow the threat display behaviour previously mentioned. Be careful of following behaviour, walking the fence, bellowing, a cow in heat and the bull that protects the cow, thereby attacking the handler. Remember, an animals first attack should be its last and it should be sent to the slaughterhouse, see Hoard's Dairyman, November 1998 page 787. BCVA 2001 VOL 9 PART 1 Animal care has a profound effect on their temperament and this is not always taken into consideration. For example, bull calves should never be teased, played with as a calf, treated roughly or rubbed vigorously on the forehead and area of the horns. You should stroke under the chin (rather than on top of the head) as an appeasement, taming, grooming-like behaviour. This is essentially the way cattle groom each other. Learn to be a good observer Observation of dairy cattle has been going on for centuries and helps to raise knowledge and improves husbandry techniques. A more logical approach to the study of cow behaviour and training is now advocated, linking it with commercial operations. Time saved through today's automation should be invested in observing animals. A knowledge of normal behaviour patterns provides an understanding about cattle and results in improved care and handling that will achieve and maintain higher milk yields, worker and animal comfort and welfare. The National Institute for Animal Agriculture, formerly known as the Livestock Conservation Institute, Bowling Green, Ky., has prepared an excellent training video entitled "Understanding dairy cattle behaviour to improve handling and production" (Hoard's Dairyman April 10 1993 page 336). Dairy cattle must fit in well with their herdmates, as well as their handlers. For those who like to work with dairy cattle, proper mental attitude must blend in with skilful management and humane care in today's highly competitive, technological, urban-based society. 88 Artificial Breeding - Does Your Repro Programme Measure Up? ABSTRACT How do you measure the success of you're A.I. breeding programme? Is there a better way to measure its success? Are you satisfied with the number of pregnancies achieved after each veterinary pregnancy check? If not, read on! For many years, we have measured the A.I. breeding programme success by examining DHI records and looking at calving intervals and services per conception. The disadvantage with using this easily calculated data is that it can be misleading. Acceptable calving intervals and low services per conception can be maintained through high culling rates, exclusive culling involving infertile cows, or by good management. Further, calving intervals and services per conception only reflect success in cows that become pregnant while ignoring those that are open and designated as culls. In other words, calving intervals and services per conception are only calculated for cows that have conceived, thus ignoring all other cows in the herd that are not pregnant but part of the breeding herd. Measure your success One simple way to measure the success of you're A.I. breeding programme is to do some quick calculations after each pregnancy diagnosis by your veterinarian. You need to determine three factors. We will call them A, B and C. • Factor A involves all cows inseminated during the breeding period between your minimal days pregnant Hoards Dairyman November 2000

CATTLE PRACTICE before you present a cow for pregnancy diagnosis (40 days in the example below) and the number of days between pregnancy check dates (7 days in the example below). For example, say you present cows that are at least 40 days pregnant and your veterinary practitioner visits your herd every 7 days. Then the number of inseminations performed during the breeding week that occurred 40-46 days before today's pregnancy check is Factor A. • Factor B is the number of cows presented for pregnancy diagnosis. • Factor C is the number of cows diagnosed pregnant. Now you can make these three calculations:- Conception rate = C ¸ A Palpation conception rate = C ¸ B Repeat heat detection rate = (A-B) ¸(A-C) What calculations reveal The conception rate reflects the fertility level for cows you chose to inseminate after detected oestrus, by appointment, timed A.I., or both. The palpation conception rate measures the proportion of the cows palpated that were pregnant. Averaged over many pregnancy diagnoses, the palpation conception rate runs very close to the repeat heat detection rate. So, after each pregnancy check, you have an idea of how good or not so good your heat detection was during that breeding week (40 - 46 days ago). The preceding calculations are quick and easily obtained, but they fail to show what was your farm's true pregnancy rate because the denominator (Factor A) does not include all cows eligible for insemination during that breeding week. These cows are those that were not inseminated following an oestrus synchronisation programme (used before first services) and those spontaneous first or repeat heats that went undetected. For example, if you are A.I. breeding cows only after expressed oestrus and your heat detection rate is 80%, you fail to A.I. breed 20% of the cows showing heat during each breeding week. If you are using an oestrus synchronisation programme and inseminate cows only after detected oestrus, you likely missed the opportunity to initiate pregnancy in some oestrus synchronised cows because they were not inseminated buy appointment. Another success measure Figure 1 shows six conception rate curves. These curves are calculated from your heat detection and conception rate. For example, if your heat detection BCVA 2001 VOL 9 PART 1 rate is 60% and your conception rate (pregnancies initiated in cows that you chose to A.I.). was 50%, then your true farm pregnancy rate is 30% (the point where the 60% heat detection rate intersects the 50% conception rate curve marked by arrows). In other words of all cows eligible to be inseminated during each breeding week, you are impregnating only 30%. You are missing the opportunity to inseminate 40% of the eligible cows in oestrus. By using an ovulation synchronisation programme that allows one to inseminate all cows using a timed A.I., you can raise your chances of impregnating more cows during each breeding week. This will happen if the conception rate achieved after timed A.I. is nearly equal to what you could achieve when cows are inseminated after detected oestrus. In this case, you are inseminating more cows or your A.I. submission rate is 100%. Using the previous example, the heat detection or, in this case, A.I. submission rate, becomes 100%; so the potential pregnancy rate is now 50%. In other words, the conception rate is now the same as the pregnancy rate because all eligible cows are inseminated. Raise submission rates The question now becomes - What can I do to boost my A.I. submission rates? For cows to be inseminated the first time after calving, I believe that is best achieved by using the Presynch + Ovsynch protocols. This programme should be followed by good heat detection to detect repeat heats. In addition, all cows found open after pregnancy diagnosis (Resynch of open cows) should go on the Ovsynch protocol again (Figure 2). Even when no repeat oestrus is detected after each A.I. breeding, this procedure guarantees that each cow is inseminated every 50 days (40 days to pregnancy check + 10 days to inseminate after the Ovsynch protocol). Make no mistake, the value of excellent heat detection is underscored but the fact that when a repeat oestrus is detected, each open cow can be inseminated every 20-22 days (duration of one oestrous cycle). If your heat detection is only 50%, then this interval between inseminations approaches 30-40 days. Using a good heat detection programme coupled with some resychronisation of open cows after pregnancy diagnosis should increase your weekly A.I. submission rates. As a result, your true herd pregnancy rate will increase, as well. Happy A.I. breeding! 89

CATTLE PRACTICE BCVA 2001 VOL 9 PART 1 90 Figure 1. Determine your conception rate Figure 2. Here is how to incorporate Presynch, Ovsynch and Resynch into your herd's breeding programme.

CATTLE PRACTICE ABSTRACT Second only to feed costs for the milking herd, heifers are one of the biggest expenses on a dairy. Unfortunately, they are also one of the most overlooked areas of the operation. Replacement heifers are an investment for the future, so efficiency and lifetime profitability are important. Typically, heifer raising accounts for one-fifth of the total expenses of milk production. Feed costs generally represent slightly more than one-half of the total heifer rearing expenses. If you work with heifers, there are a few things you need to know to keep costs down. Age at first calving is critical. An older first calving age will result in raised costs by increasing days to calving, more heifers on the farm and lost production. In this case, we need more heifers on the farm because it will take them longer to calve in and replace the cull cows. Here's an example to help figure the number of replacement heifers you'll need. If your farm has 100 cows and a cull rate of 30%, you will need to have 30 heifers entering the herd every year. Because these are 2 year olds, you will also need 30 young heifers to replace next years cull cows. This is assuming your age at first calving is 24 months. If you raise the age at first calving to 28 months, you will need 35 heifers each year, a total of 70 heifers from birth to 2 years of age. In other words, increasing your calving age requires more heifers, in this case, 10 more heifers. The cost to raise a heifer to 24 months is about $1,200, or an average $50 per month. The cost to raise the 10 more heifers results in an increased cost of $15,200 (10 heifers x $50/month x 28 months = $15,200). So you can see how this quickly adds up. Achieve earlier calving age The most economical age at first calving is 22.5 to 23.5 months, if heifers are of adequate size. To achieve a younger age at calving, heifers need to be bred at an early age. Therefore, heifers must reach puberty and be the correct size. The start of puberty is more closely associated with weight and not age. This means a rapid growth rate and the full expression of genetic potential of the heifers needs to be accomplished with the feeding programme. The feeding programme may also influence udder development and subsequent lactation performance. Udder development can be divided into prepubertal and postpubertal phases. Within each phase, there are different rates. At one phase, the udder grows at the same rate as the body. Another phase has udder growth exceeding body growth. BCVA 2001 VOL 9 PART 1 During the prepubertal phase, the udder and body grow at the same pace from birth to three months, udder growth exceeds body growth from 3-9 months (puberty). After puberty, udder growth returns to early calfhood levels until the heifer becomes pregnant. Then, the udder growth rate exceeds the body again. Hormones play a major role in the changes between growth rates of the mammary gland compared to the body. How do we feed them? Studies have shown that increased body weight gain reduces udder development during the allometric phase. Researchers from Ontario found lower DNA concentration, less udder secretory tissue (the tissue responsible for manufacturing milk) and more fat deposits in the udders of heifers fed for high rates of growth. Wisconsin researchers found poorer lactation performances in heifers fed for accelerated growth and bred to calve before 22 months of age. They found that the negative influences of accelerated growth appear to be connected with early breeding and calving. Other biological mechanisms may play a role in reduced milk yield of heifers reared for accelerated growth. These studies lead us to believe that heifers fed restricted diets will produce more milk. However, there is conflicting data regarding this matter. Research from New York indicated that body weight and body condition score at calving accounted for more difference in milk production than average daily gain. The heifers fed for accelerated growth and bred for early calving were shorter (hip height) and weighed less at calving than heifers raised for a lesser rate of gain. Kansas researchers found that accelerated growth can be achieved without excessive fattening which is typically seen in heifers fed high energy diets. The researchers boosted energy in the diet but also raised the other major nutrients including crude protein, metabolisable energy, calcium (Ca), phosphorus (P) and vitamins A and D. Heifers fed the accelerated diet gained more body weight and had greater increases in height, body length and heart girth than other heifers. Therefore, it seems balancing the energy in the diet with protein and other major nutrients is the key to accelerating growth without excessive conditioning and lower milk yield. In New Hampshire, researchers evaluated the requirements of the weaned calf (6 weeks - 6 months) for feed protein fractions. They found that ruminally 91 Feed Your Heifers to Calve Earlier Hoards Dairyman November 2000

CATTLE PRACTICE degradable protein (protein that is broken down by rumen micro-organisms) at 9.56% of feed dry matter and bypass protein (protein that bypasses the rumen and is digested in the stomach and intestine) at 8.65% of feed dry matter was optimal for growth and feed efficiency. Calves on this diet gained 2.1 pounds per day. Stair-step plan promotes growth A stair-step nutrient regimen is another method that can be used to accelerate growth without excessive conditioning. This regimen induces compensatory growth which is the accelerated growth that occurs after a period of growth restriction ends. Compensatory growth influences tissue development and metabolism. It results in greater body weight gain, better appetite, improved feed intake, increased efficiency of energy utilisation and less maintenance requirements because of a lower basal metabolic rate. Compensatory growth also leads to positive changes in hormone status, altered body tissue composition and overall improved efficiency of growth compared with conventionally fed heifers. Studies from Korea and North Dakota found increased efficiency of BCVA 2001 VOL 9 PART 1 growth and a 6-9% jump in milk production for heifers raised on a stair-step nutrient regimen. Accelerated growth and an early age at first calving can be achieved without detrimental effects to mammary development and lactation performance. Forage and concentrate analysis are important to accurately balance a diet to get the most growth from the heifers. Average daily gains of 1.7 - 2.0 pounds per day for large breeds and 1.3 - 1.6 pounds per day for small breeds are appropriate. Higher gains can be achieved if calves do not get too fat. Evaluate heifers monthly to be sure that they are growing properly to maximise profitability. During these evaluations, heifers should be weighed or taped, wither and hip heights should be measured. Your heifers' frame sizes should be growing in proportion with weight to avoid over conditioning. Learn to body condition score your heifers. Observing the animals for illness or injury and monitoring health and vaccination records will also improve the profitability of your replacement heifers. Replacement heifers are an investment for the future, so invest wisely. 92