Selecting an appropriate genetic evaluation model for selection in a developing dairy sector.

This study aimed to identify genetic evaluation models (GEM) to accurately select cattle for milk production when only limited data are available. It is based on a data set from the Pakistani Sahiwal progeny testing programme which includes records from five government herds, each consisting of 100 to 350 animals, with lactation records dating back to 1968. Different types of GEM were compared, namely: (1) multivariate v. repeatability model when using the first three lactations, (2) an animal v. a sire model, (3) different fixed effects models to account for effects such as herd, year and season; and (4) fitting a model with genetic parameters fixed v. estimating the genetic parameters as part of the model fitting process. Two methods were used for the comparison of models. The first method used simulated data based on the Pakistani progeny testing system and compared estimated breeding values with true breeding values. The second method used cross-validation to determine the best model in subsets of actual Australian herd-recorded data. Subsets were chosen to reflect the Pakistani data in terms of herd size and number of herds. Based on the simulation and the cross-validation method, the multivariate animal model using fixed genetic parameters was generally the superior GEM, but problems arise in determining suitable values for fixing the parameters. Using mean square error of prediction, the best fixed effects structure could not be conclusively determined. The simulation method indicated the simplest fixed effects structure to be superior whereas in contrast, the cross-validation method on actual data concluded that the most complex one was the best. In conclusion it is difficult to propose a universally best GEM that can be used in any data set of this size. However, some general recommendations are that it is more appropriate to estimate the genetic parameters when evaluating for selection purposes, the animal model was superior to the sire model and that in the Pakistani situation the repeatability model is more suitable than a multivariate.

Echinococcus granulosus and other intestinal helminths: current status of prevalence and management in rural dogs of eastern Australia.

OBJECTIVES: Ascertain the prevalence of intestinal helminths in rural dogs from eastern Australia and Tasmania. Identify farm management practices contributing to the perpetuation and transmission of Echinococcus granulosus. METHODS: Helminth infection in dogs was determined microscopically through faecal flotation. Infection with E. granulosus was determined via faecal antigen-capture ELISA and coproPCR. Taeniid eggs were identified using molecular methods. Data on dog management and owner understanding of hydatid disease were collected via questionnaire. RESULTS: Faeces were collected from 1425 Australian rural dogs (1119 mainland; 306 Tasmania). Eggs of hookworms were most prevalent, up to 40.2%, followed by whipworms (Trichuris vulpis), up to 21.2%. Roundworms (Toxocara canis and Toxascaris leonine) were least common, up to 6.1%. Taeniid eggs were found in 11 dogs (5 Taenia pisiformis; 2 T. serialis; 4 T. hydatigena); 2 of the T. hydatigena-infected dogs were also E. granulosus coproantigen-positive. Of the 45 dogs found to be E. granulosus coproantigen-positive, 24 were in Tasmania, 16 in NSW, 3 in Victoria and 2 in Queensland. Three Tasmanian coproantigen ELISA-positive dogs were also coproPCR-positive. The most common dog ration was commercial dry food, but half the owners fed raw meat to their dogs and some fed offal of lambs (8.9%) or mutton (7.8%). More than half (69%) of owners weighed their dogs before deworming. Few dewormed their dogs often enough to ensure they remained cestode-free and owners hunting wildlife usually left carcases where they were shot. CONCLUSIONS: E. granulosus is still present in Australian rural dogs, including Tasmania, but at low levels. Owner behaviour perpetuates transmission of cestodes.

Hazard perception of Dutch farmers and veterinarians related to dairy young stock rearing.

A group of 110 dairy farmers and 26 bovine veterinarians participated in a web-based questionnaire using the adaptive conjoint analysis technique to rank their perception regarding several hazards during 6 subsequent periods of the process of dairy young stock rearing. The method applied only involved selected respondents with a high consistency in their answering (correlation >30%). For the ranking, answers were first transformed into a utility score (US) for each hazard. The final ranking for each of the 6 periods was based on the US per hazard separately for farmers and veterinarians. Besides the ranking, the absolute values and the US itself were also compared between farmers and veterinarians to determine any statistically significant differences between the levels of the score despite the ranking. The overall conclusion is that, for almost every designated period, the ranking of the hazards differed between farmers and veterinarians. Only 1 period was observed (period IV, Pregnancy period until 4 weeks before calving) where veterinarians and farmers had the same top 3 ranking of the hazards, namely "Mastitis," "Abortion," and "Poor growth rate of the pregnant heifer." Major differences between farmers and veterinarians were seen during period II (feeding milk until weaning) for the hazard "Diarrhea in older calf," which was considered less important by farmers compared to veterinarians, and period number III (weaning until insemination) for "Over-condition," which, again, was seen as the most important hazard by veterinarians, but only ranked as number 5 by farmers. Besides the ranking, significant differences in absolute US values between veterinarians and farmers were seen in "Infection with Johne's disease" (14.5 vs. 7.8), "Diarrhea in newborn calf" (18.2 vs. 12.2), and "Insufficient feed intake" (16.2 vs. 8.4) in period I (colostrum until transition to milk replacer). Lameness represented the most important significant difference in absolute values in period III (weaning until insemination; 6.3 vs. 14.3), which was again significant in period V (4 wks before calving until calving; 7.4 vs. 12.1). The outcome of this study shows that hazard perception of veterinarians and farmers differs for most rearing periods (in ranking and absolute values). The outcome of this study can be used for 2 purposes: first, to improve communication between farmers and their consulting veterinarian about hazards and hazard perception in young stock rearing; and second, the US scores can be used to select top priority hazards which should at least be integrated into management advisory programs to improve dairy young stock rearing.

Expert opinion on ranking risk factors for subclinical mastitis using a modified Delphi technique.

AIM: To collate the expert opinion of Australian dairy practitioners on the relative importance of risk factors for subclinical mastitis in dairy cattle. METHODS: A modified Delphi technique was used to collect the data over two rounds. First, participants were asked to complete a survey involving ranking the level of importance of 42 risk factors on the incidence of subclinical mastitis on a scale from 1 to 10 for two categories of subclinical mastitis; contagious and environmental. After presenting and discussing the results of the first survey, the participants were asked to complete the same survey a second time. To rank the risk factors and identify the consensus amongst the participants, the median and total variation of answers were calculated and compared between the two surveys. RESULTS: The most important factors identified by the respondents after the second survey for contagious subclinical mastitis were: Teat Disinfection Post-milking, Management of High Cell Count Cows and Presence of Chronically Infected Mastitis Cows in the Herd. The most important factors for environmental subclinical mastitis were Cleanliness of the Environment and Technique of Teat Disinfection Post-milking. CONCLUSIONS: A movement toward consensus for the more important factors and a movement away from consensus for the less important factors in the second survey were observed. The most important factors for subclinical mastitis were found to be: teat disinfection post-milking, management of high cell count cows, presence of chronically infected mastitis cows in the herd and cleanliness of the environment.

Extent of utilisation of dual-purpose wheat for grazing by late-pregnant and lambing ewes and producer-reported incidence of health issues in southern New South Wales.

OBJECTIVE: To investigate the extent of using dual-purpose wheat for grazing by late-pregnant and lambing ewes in southern New South Wales (NSW) and the effect on ewe health. METHODS: A questionnaire was mailed to sheep producers in the mixed-farming districts of the Hume Livestock Health and Pest Authority area in NSW, seeking information on whether there had been grazing by late-pregnant or lambing ewes of dual-purpose wheat during the period 2005-10. Information collected included general farm operation details, as well as the producers' experiences specific to grazing reproducing ewes on wheat, including causes and extent of disease and the producers' supplementation practices. RESULTS: Of the 202 respondents to the survey, 43% identified that they had grazed late-pregnant and/or lambing ewes on dual-purpose wheat during the period 2005-10. Of the producers, 71 had grazed reproducing ewes on wheat in 2010 and reported a mean disease incidence of 2.6% (range, 0.0-21.3%). Dystocia, pregnancy toxaemia, foot abscess and grass tetany were the most commonly reported diseases in ewes grazing wheat in 2010. The majority of producers (92%) supplied supplement to ewes grazing wheat in 2010, including mineral supplements (85%), roughage (58%) and grain (18%). Thirty percent of producers who grazed ewes on wheat between 2005 and 2009 experienced higher than normal rates of ewe health problems, reporting a mean of 7.9% ewes in these flocks with health problems. CONCLUSION: Metabolic diseases such as pregnancy toxaemia, hypocalcaemia and grass tetany appear to be important diseases of reproducing ewes grazing wheat pasture.

Incidence of calf scours and associated risk factors in southern New South Wales beef herds.

OBJECTIVE: The aim of this study was to identify the incidence of morbidity and mortality associated with calf scours in beef calves between birth and 14 days of age. Farm characteristics, animal factors and management practices were also assessed for any association with calf scours being present on the farm. METHODS: A questionnaire and return address envelope were distributed to 721 farms with at least 50 head of beef cattle in the Hume area of New South Wales, Australia. RESULTS: In total, 147 (20.4%) farmers responded to the survey, of which 76 (51.7%) indicated calf scours did occur on their farm. On average, farmers estimated the morbidity of calf scours was 4.5%, but only 0.2% of all calves died as a result of scours. Affected herds were more likely to have multiple breeds and a higher proportion of cows with mismothering problems or weak calves compared with unaffected herds. These differences were confirmed with regression analysis. A large proportion of farmers with affected herds reported the loss of many calves from 'unexplained' or 'sudden' death within the first 14 days of life. CONCLUSIONS: The incidence of calf morbidity was lower and mortality was within the same range compared with other studies on beef farms around the world. The high percentage of farms reporting losses from 'unexplained' or 'sudden' death of calves requires further monitoring and diagnostic and economic investigations.

Workplace stress, mental health, and burnout of veterinarians in Australia.

OBJECTIVE: To determine the frequency of the states of depression, anxiety, stress and burnout using internationally validated methods and to relate these to the demographic characteristics of veterinarians in Australia. METHODS: A postal survey of registered veterinarians with at least one year's experience and whose address was available; 1947 returned the questionnaire providing data for analysis. RESULTS: Overall, veterinarians describe higher levels of depression, anxiety, stress and burnout than the general population. The severity of these states was determined by gender, background, type of practice and years after graduation. CONCLUSIONS: Modifying the curricula of veterinary schools to include the teaching of personal cognitive and coping skills to undergraduate veterinary students, the provision of the opportunity to enhance these skills throughout their veterinary career and changes in the veterinary workplace could result in improved mental health, increased job engagement and work satisfaction.

Ranking experts' preferences regarding measures and methods of assessment of welfare in dairy herds using Adaptive Conjoint Analysis.

Welfare in dairy herds can be addressed using different concepts. The difficulty is to extract which measures are the most important to practically address welfare at the herd level and the methods to assess traits considered most important. Therefore, the preferences of 24 acknowledged European welfare experts were ranked regarding 70 measures suitable to assess dairy cattle welfare at herd level using the Adaptive Conjoint Analysis (ACA; Sawtooth Software, Inc., Sequim, WA) technique. The experts were selected on the basis of 3 criteria: at least 5 yr experience in animal welfare research; recent scientific publications in the field of animal welfare; and, at the most, 3 animal species including dairy cattle as their field of expertise. The 70 traits were ranked by using the median ACA questionnaire utility scores and the range between the answers of the 24 experts. A high utility score with a low range between the answers of the experts was considered as suitable to assess welfare at farm level. Measures meeting these criteria were prevalence of lameness cases (107.3±11.7), competition for feed and water (96.4±13.9), and number of freestalls per 10 cows (84.8±13.3). Based on the utility score alone, these former measures were replaced by stereotypic behavior (111.7±17.1), prevalence of lameness cases (107.3±11.7), body condition score (108.0±18.9), and hock lesions (104.7±16.1). Subsequently, to demonstrate that the ACA technique can be used to rank either well-known or inconclusive methods of assessment, the methods for the traits lameness cases and the hygiene of the calving pen were ranked using another 2 ACA questionnaires. The results are based on the opinions of selected, internationally acknowledged dairy cattle welfare experts within the European Union. In the future, other parties like dairy farmers and farmers' organization should be included to achieve consensus about the most suitable traits applicable in practice. The currently investigated traits do not always apply to all dairy husbandry systems across the world, but are based on a system that includes indoor housing during winter. It is concluded that ACA is a useful technique to rank the different scientific opinions of experts regarding suitable traits and methods of assessment of dairy cattle at the herd level.

Subclinical mastitis and associated risk factors on dairy farms in New South Wales.

OBJECTIVE: To determine the current prevalence of subclinical mastitis (SCM) and associated risk factors on dairy farms in New South Wales. METHODOLOGY: A survey was sent to 382 dairy farmers to acquire information on the relevant risk factors associated with SCM. RESULTS: The average herd prevalence of SCM among the 189 respondents (response rate 49.5%) was 29%. Farmers who had herds with a low prevalence (<20% cows with individual somatic cell count (ISCC) >2 × 105 cells/mL) more frequently wore gloves during milking (26% vs 62%), used individual paper towels for udder preparation (16% vs 62%), fed cows directly after milking (47% vs 87%) and more frequently treated cows with high ISCC (69% vs 80%) than farmers who had herds with a high prevalence of SCM (>30% cows with ISCC >2 × 105 cells/mL). The latter more often used selective dry cow therapy (52% vs 24%), compared with low prevalence herds. CONCLUSION: The prevalence of SCM in this cross-sectional study is comparable or lower than reported in other studies from North America and the European Union. The outcome provides a benchmark for the current focus of the NSW dairy industry on the management practices associated with a low prevalence of SCM, such as wearing gloves, using paper towels and feeding cows directly after milking.

Short communication: influence of sampling interval on the accuracy of predicting bulk milk somatic cell count.

Although bulk milk somatic cell count (BMSCC) is, in most instances, not a good proxy for actual average herd somatic cell count (SCC), BMSCC is the only SCC parameter available to monitor trends in udder health for a large number of farms worldwide. The frequency of sampling BMSCC varies considerably between countries, and it is unknown to what extent the sampling interval of BMSCC or variation in BMSCC data itself influences the accuracy. The aim of this study was to assess the effect of sampling interval and variation of the BMSCC data on the accuracy to predict BMSCC. Because BMSCC is measured at regular time intervals, an artificial neural network (ANN) was used to determine both the effect of sampling interval and variation of the BMSCC data. The intervals examined in this study ranged from 4 to 14 d and were compared with the baseline of a standard 2-d sampling interval. The BMSCC data were collected every other day for a 24-mo period on 949 farms, and all series were created by exclusion of BMSCC data in between the original 2-d sampling interval series. The effect of variation of BMSCC was determined by comparing the error of the ANN model in 2 subsets of farms, those with the lowest SD (n=239) and those with a high SD of BMSCC data (n=236). No significant differences were found in any of the sampling intervals between the 2 cohorts of low and high SD in BMSCC. Overall, compared with the 2-d sampling interval, on average the error of the ANN model was 32,600 cells/mL for all farms included, ranging from 15,000 cells/mL (4-d interval) to 41,000 cells/mL (14-d sampling interval). Therefore, the length of the sampling interval greatly influences the usefulness of BMSCC data to monitor trends in udder health at the herd level.

Prediction of the herd somatic cell count of the following month using a linear mixed effect model.

An accurate prediction of the average somatic cell count (SCC) for the next month would be a valuable tool to support udder health management decisions. A linear mixed effect (LME) model was used to predict the average herd SCC (HSCC) for the following month. The LME model included data on SCC, herd characteristics, season, and management practices determined in a previous study that quantified the contribution of each factor for the HSCC. The LME model was tested on a new data set of 101 farms and included data from 3 consecutive years. The farms were split randomly in 2 groups of 50 and 51 farms. The first group of 50 farms was used to check for systematic errors in predicting monthly HSCC. An initial model was based on older data from a different part of the Netherlands and systematically overestimated HSCC in most months. Therefore, the model was adjusted for the difference in average HSCC between the 2 sets of farms (from the previous and current study) using the data from the first group of 50 farms. Subsequently, the data from the second group of 51 farms were used to independently assess this final model. A null model (no explanatory variables included) predicted 48 and 59% of the HSCC within the predetermined range of 20,000 and 30,000 cells/mL, respectively. The final LME model predicted 72 and 81% of the HSCC of the next month correctly within these 2 ranges. These outcomes indicate that the final LME model was a valid additional tool for farmers that could be useful in their short-term decisions regarding udder health management and could be included in dairy herd health programs.

Veterinary advice for entrepreneurial Dutch dairy farmers: from curative practice to coach-consultant: what needs to be changed?

Dairy farms are tending to become larger, with a milk quota of more than 8 tons a year, and are managed by entrepreneurial dairy farmers with their own specific characteristics and farming style. Some Dutch veterinary practices appear unable to respond to this different style and often do not serve such farms or lose them as client. Moreover, the veterinary curriculum often focuses on traditional, family-run, smaller dairy operations and not on larger farms, which raises the question whether newly qualified veterinary practitioners are adequately trained to provide these entrepreneurial farmers with the services they require. This article addresses the characteristics of entrepreneurial dairy farmers and those of cattle practitioners, to determine whether cattle practitioners need to acquire other skills to better prepare them for their coaching-consultant tasks on larger dairy farms.

Effect of herd characteristics, management practices, and season on different categories of the herd somatic cell count.

In this study, the contribution of management practices, herd characteristics, and seasonal variables to the herd somatic cell count (SCC) was quantified in herds with low (<150,000 cells/mL), medium (150,000-200,000 cells/mL), and high (>200,000 cells/mL) herd SCC (HSCC). Selection of the variables was performed using a linear mixed effect model; HSCC was calculated as the arithmetic mean of the individual cow's SCC. The data concerning management practices were derived from 3 questionnaires on mastitis prevention and management practices on 246 Dutch dairy farms. The monthly Dairy Herd Improvement test data of these 246 farms were used to calculate the herd characteristics and seasonal effects. None of the management practices were associated with HSCC in all 3 HSCC categories. Some variables only had a significant association with HSCC in one HSCC category, such as dry premilking treatment (-9,100 cells/mL in the low HSCC category) or feeding calves with high SCC milk (11,100 cells/ mL in the medium HSCC category). Others had an opposite effect on HSCC in different HSCC categories, such as average parity (-6,400 and 11,000 cells/mL in the low and medium HSCC category, respectively) and feeding calves with fresh milk (10,300 and -9,700 cells/ mL in the low and high HSCC category, respectively). We conclude that, given the individual Dairy Herd Improvement data and information on management practices of an individual farm, it is possible to provide quantitative insight into the contribution of these different variables to the HSCC of an individual farm. Being able to provide such insight is a prerequisite for interpretation, prediction, and control of HSCC on individual dairy farms.

Short communication: Comparison of bulk milk, yield-corrected, and average somatic cell counts as parameters to summarize the subclinical mastitis situation in a dairy herd.

In this study, the correlation was determined between the prevalence of high cow-level somatic cell count (SCC >250,000 cells/mL), a summary of the subclinical mastitis situation in a dairy herd, and 3 average herd SCC parameters: bulk milk SCC (BMSCC), yield-corrected test-day SCC (CHSCC), and the arithmetic average test-day SCC (HSCC) of the lactating herd. The herd prevalence of cows with an SCC of >250,000 cells/mL was calculated by using Dairy Herd Improvement data. Herds were included if BMSCC was sampled within 2 d of the Dairy Herd Improvement test day and if the BMSCC did not exceed 400,000 cells/mL. The interval between sampling, 0, 1, or 2 d, did not significantly influence the correlation between BMSCC and the prevalence of high SCC. The correlations between the prevalence of high SCC and BMSCC, yield-corrected test-day SCC, and HSCC, examined by using a linear regression model, were 0.64, 0.78, and 0.89, respectively. Therefore, it can be concluded that, based on the highest correlation, HSCC is a more appropriate parameter than BMSCC to summarize the average herd subclinical mastitis situation in a dairy herd.

[Transvaginal aspiration as first treatment of ovarian follicular cysts in dairy cattle under field circumstances]. / Transvaginale aspiratie als primaire behandeling van ovariële follikelcysten bij melkkoeien onder praktijkomstandigheden.

On dairy farms covered by the ambulatory service of the Department of Farm Animal Health, 55 Holstein-Friesian cows with suspected ovarian follicular cysts on the basis of rectal palpation underwent confirmatory transrectal ultrasonography. An ovarian follicular cyst was confirmed in 28 cows (50.9%) and was treated by single transvaginal-guided needle aspiration. Cows with a corpus luteum or a luteinized cyst were not treated. After aspiration, 82.1% (n=23) of the cows showed oestrus behaviour at 13.3 +/- 6.0 days. Artificial insemination was performed during the first heat after cyst aspiration and resulted in a pregnancy rate of 64.2%. In conclusion, single transvaginal-guided needle aspiration of ovarian follicular cysts is an easy and good method for the treatment of follicular cysts. Moreover, it is a safe and good alternative method for the manual, active rupturing of cysts during rectal palpation.

The Hazard Analysis Critical Control Point's (HACCP) concept as applied to some chemical, physical and microbiological contaminants of milk on dairy farms. A prototype.

Quality management on dairy farms becomes more and more important regarding the different areas of animal health, animal welfare and food safety. Monitoring animals, farm conditions and farm records can be extended with risk identification and risk management. The hazard analysis critical control point's system is useful as an on farm strategy to control the product as well as the production process on the areas of animal health, animal welfare and food safety. This article deals in detail with the question how to develop a qualitative method where risk can be defined as an interaction between probability and impact. Two parts of the production process (milk harvest and treatment of cows) where used as an example how to apply the hazard analysis critical control point's system on chemical, physical and microbiological contaminants of milk. Not just only by summarizing the different critical checkpoints for each area but also by giving them a precise judgement of probability and impact.

[Veterinary supervision of dairy facilities in the Netherlands: what do veterinarians think about participating and non-participating cattle owners?]. / Veterinaire begeleiding van melkveebedrijven in nederland: hoe denkt de dierenarts over deelnemende en niet-deelnemende veehouders?

Dairy herd health and production management programmes are being used increasingly more often, also in the Netherlands. However, little is known about the rationale behind the farmers' decision to participate or not to participate. This paper reports the results of a questionnaire survey among cattle practitioners about why they thought farmers did or did not participate in these programmes, the perceived advantages and disadvantages of such programmes, the extent to which the respective farming areas were represented in the programmes, and the reasons why farmers stopped participation in the programme. Furthermore, the ways in which the practitioners try to convince the non-participating farmers to join the programme were addressed. The future of dairy herd health programmes in the context of quality assurance programmes and the way the farmers think about these developments were discussed by the practitioners.

[Veterinary assistance to dairy farms in the Netherlands: an assessment of the situation by dairy farmers]. / Veterinaire begeleiding van melkveebedrijven in Nederland: een situatiebeoordeling door melkveehouders.

A questionnaire-based study was conducted among 466 dairy farmers in the Netherlands. The study investigated the experiences and opinions of dairy farmers about veterinary herd health and production management programmes. The dairy farmers were selected at random, and thus some took part in such programmes whereas others did not. The questionnaire comprised general questions about the farm operation and specific questions about the herd health programme and the practice conducting it, as well as perceived advantages and disadvantages of the veterinary programme. Farmers who did not participate in such programmes were questioned about their reasons for not participating. Both groups were questioned about future perspectives and opportunities. The costs of the programme appeared to be a drawback for participation but not as much as perceived by the practices. According to farmers, programmes focus too much on curative aspects and too little on analysis or prevention, where the needs are. Farm areas not included in the programme are so far not yet covered by other institutions, contrary to the expectations of the veterinarians. In the future, the farmers would be willing to take part in similar or expanded programmes, provided that certain conditions, such as product definition, structure, planning, costs, are properly met.