Mf Pyman

Periparturient immunosuppression and strategies to improve dairy cow health during the periparturient period

Common health problems observed during peripartum include milk fever, mastitis, fatty liver disease, ketosis, dystocia, retained placenta, metritis, hypomagnesaemia and abomasal displacements. The increased incidence of health problems observed during the periparturient period can be partly attributed to suboptimal immune responses. Factors contributing to decreased periparturient immunity include the act of parturition itself, impaired leukocytic activity, effects of colostrogenesis and lactogenesis, and associated hypocalcemia and negative energy balance. Nutritional and other management strategies represent a relevant short-term strategy aimed at improving the health and welfare of the transitioning cow. Additionally, it is important to consider improving the health of dairy herds through the genetic selection of animals with enhanced robustness by identifying those with superior disease resistance or resilience in the face of infection. As a consequence these animals are better able to cope with the production and environmental stresses. These may provide long-term selection strategies for improving the health and welfare of the transitioning cow particularly when combined with sound management practices, allowing dairy cattle to reach their full genetic potential.

High-quality care improves outcome in recumbent dairy cattle.

OBJECTIVE To investigate the influence of the quality of care on outcome and occurrence of secondary damage in recumbent dairy cows. METHODS Recumbent dairy cows were monitored during their recumbency under field conditions in South Gippsland, Victoria, Australia. The cause of the original recumbency of 218 downer cows was determined and any secondary damage, day 7 status, final outcome and the nursing conditions of the cows were recorded. A four-tiered grading system describing nursing quality was developed to allow analysis of its influence on outcome and on the occurrence of secondary damage. RESULTS Day 7 outcome, final outcome and occurrence of important secondary damage were very strongly associated with the level of overall care provided to the recumbent cows. There was a decrease in the percentage of cows recovering by day 7 from 33% to 0%, a decrease from 45% to 0% of cows eventually recovering and an increase from 68% to 100% of cows with clinically important secondary damage as overall care decreased. CONCLUSION Management of recumbent cattle is potentially a significant animal welfare issue for the dairy industry and their care is a very important but often under-appreciated aspect of their management. Recovery is positively influenced by high-quality care by improving the chances of recovery from the initial cause of recumbency and by reducing the occurrence of secondary damage. Recumbent cows must either be nursed at a high level of care or euthanased promptly.

An automated walk-over weighing system as a tool for measuring liveweight change in lactating dairy cows

Automated walk-over weighing systems can be used to monitor liveweights of cattle. Minimal literature exists to describe agreement between automated and static scales, and no known studies describe repeatability when used for daily measurements of dairy cows. This study establishes the repeatability of an automated walk-over cattle-weighing system, and agreement with static electronic scales, when used in a commercial dairy herd to weigh lactating cows. Forty-six lactating dairy cows from a seasonal calving, pasture-based dairy herd in southwest Victoria, Australia, were weighed once using a set of static scales and repeatedly using an automated walk-over weighing system at the exit of a rotary dairy. Substantial agreement was observed between the automated and static scales when assessed using Lins concordance correlation coefficient. Weights measured by the automated walkover scales were within 5% of those measured by the static scales in 96% of weighings. Bland and Altmans 95% limits of agreement were -23.3 to 43.6 kg, a range of 66.9 kg. The 95% repeatability coefficient for automated weighings was 46.3 kg. Removal of a single outlier from the data set increased Lins concordance coefficient, narrowed Bland and Altmans 95% limits of agreement to a range of 32.5 kg, and reduced the 95% repeatability coefficient to 18.7 kg. Cow misbehavior during walk-over weighing accounted for many of the larger weight discrepancies. The automated walk-over weighing system showed substantial agreement with the static scales when assessed using Lins concordance correlation coefficient. This contrasted with limited agreement when assessed using Bland and Altmans method, largely due to poor repeatability. This suggests the automated weighing system is inadequate for detecting small liveweight differences in individual cows based on comparisons of single weights. Misbehaviors and other factors can result in the recording of spurious values on walk-over scales. Excluding outlier weights and comparing means of 7 consecutive daily weights may improve agreement sufficiently to allow meaningful assessment of small short-term changes in automated weights in individuals and groups of cows.

Factors associated with colostrum immunoglobulin G concentration in northern-Victorian dairy cows

OBJECTIVES To determine the proportion of first-milking colostrum samples produced on four northern-Victorian dairy farms that meet industry standards in terms of immunoglobulin G (IgG) concentration and to identify risk factors that affect colostrum quality. METHODS Colostrum IgG concentrations from 442 dairy cows on four farms were estimated using a Brix refractometer and risk factors for colostrum IgG concentration were determined using multivariable logistic regression. RESULTS Only 39% of samples met the definition of high quality. The strongest predictor for colostrum quality was the interval from calving to colostrum harvesting. Colostrum harvested from cows within 12 h of calving was 6-fold more likely to be high quality compared with colostrum harvested later. Colostrum from cows in ≥ 4th lactation was nearly twice as likely to be high quality compared with cows entering their 1st lactation. If the calf was not allowed to suckle from the dam prior to colostrum harvesting, the odds of producing high-quality colostrum were nearly 4-fold greater. If the cow had not leaked colostrum prior to harvesting, it was more than 3-fold more likely to produce high-quality colostrum. CONCLUSIONS The majority of samples assessed were below industry standard. Herd, lactation number, calf suckling or cow leaking colostrum prior to harvesting and time between calving and colostrum harvesting were factors that influenced colostrum IgG concentration. The results support current industry recommendations of harvesting colostrum shortly after parturition (ideally within 12 h of calving) and testing the quality of all colostrum prior to feeding to dairy calves.

Importance of secondary damage in downer cows.

OBJECTIVE To investigate the relative importance in downer cows of the primary cause of recumbency in comparison with secondary complications. METHODS Downer dairy cows were monitored during their recumbency under field conditions in South Gippsland, Victoria, Australia. The cause of the original recumbency of the 218 cows was determined and secondary damage, status on day 7 and final outcome were recorded. RESULTS Some type of secondary damage was found in 183/218 (84%) cows, of which 173/218 (79%) had damage deemed to be clinically important. By day 7, 52 (24%) had recovered and 69 (32%) eventually recovered. Of the 149 (68%) cows that were euthanased or died, 23 (15%) were deemed to have been lost solely from the primary cause, 107 (72%) from secondary damage and 19 (13%) from a combination of both. CONCLUSION There was no difference in recovery among the five broad groups of causes of primary recumbency. Secondary damage was very common and presented in a large variety of ways, with many cows having multiple types of secondary damage concurrently. For most cows the secondary damage was more important than the initial primary damage in determining their fate.

Infectious reproductive disease pathogens in dairy herd bulls.

OBJECTIVE Investigate the presence of infectious reproductive disease pathogens in dairy herd bulls in south-west Victoria, Australia, using a cross-sectional study. METHODS Dairy herd bulls from 32 herds were sampled for bovine viral diarrhoea virus (BVDV: 256 bulls, 32 herds) prior to the natural mating period, bovine herpes virus-1 prior to (10 bulls, 5 herds) and after (118 bulls, 19 herds) the natural mating period, and for Campylobacter fetus spp. and Tritrichomonas foetus after the natural mating period (61 bulls, 7 herds). BVDV was detected from an ear-notch sample using a commercially available rapid assay ELISA, bovine herpes virus-1 and T. foetus were screened for by PCR from a penile swab and preputial sample respectively, and C. fetus spp. were screened for by culture of preputial samples. RESULTS None of the bulls tested positive for BVDV antigen. Campylobacter fetus venerealis (or C. fetus fetus) was cultured in 6.6% (4/61) of bulls, representing 2 of the 7 (28.6%) farms that were not vaccinating bulls against bovine genital campylobacteriosis. Bovine herpes virus-1 was identified in 7.8% (10/128) bulls sampled; T. foetus was not identified in any samples. CONCLUSION Bovine genital campylobacteriosis is present in south-western Victoria, despite longstanding recommendations to vaccinate bulls. Screening bulls for persistent infection with BVDV is probably justified, despite the absence of persistently infected bulls in this study. Further research is warranted to investigate the potential reproductive implications of BHV-1, and the presence of T. foetus.

Postpartum anoestrus in five seasonally-calving dairy farms in Victoria, Australia

OBJECTIVE A cross-sectional study of seasonally-calving dairy cows in south-western Victoria to quantify the prevalence of anoestrus and to assess the effect of body condition score (BCS), days in milk (DIM) at mating start date (MSD) and age on the likelihood of being diagnosed as anoestrus. METHODS Age, DIM and BCS details were collected from 1795 cycling and 1399 cows diagnosed as anoestrus in five seasonally-calving dairy herds in Victoria. Multivariable logistic regression was used to quantify the association between BCS, DIM and age and the probability of being diagnosed as anoestrus. RESULTS The apparent prevalence of anoestrus in cows that took part in the study was 44% (95% confidence interval (CI) 42-46%). The risk of anoestrus increased with decreases in DIM and BCS. There was a significant interaction between BCS and DIM. For cows >90 DIM at MSD (the reference category) the odds of anoestrus in cows with BCS <4.00 was 8.05-fold (95% CI 3.2-20.2) that of cows of BCS ≥4.50. The risk of anoestrus decreased with increases in cow age. Cows aged 2 and 3-5 years had 2.4-fold (95% CI 1.79-3.22) and 1.4 (95% CI 1.11-1.77) odds of anoestrus, respectively, compared with cows aged ≥6 years. CONCLUSION Reproductive management to maximise the number of days calved at MSD and nutritional management to ensure cows are in BCS >4.5 at mating will reduce the prevalence of anoestrus in Victorian dairy herds.

The effects on ruminal pH and serum haptoglobin after feeding a grain-based supplement to grazing dairy cows as a partial mixed ration or during milking

Ruminal pH and serum concentrations of haptoglobin (Hp) were measured in order to assess the risk of subacute ruminal acidosis (SARA) in grazing cows offered rolled wheat grain twice daily in the dairy at milking (Control group; n= 64), or as a partial mixed ration (PMR group; n= 64) on a feedpad. Cows were allocated various levels of the supplement (8, 10, 12 or 14 kg dry matter/day). Ruminal pH was measured in 16 rumen-fistulated cows (eight PMR and eight Control group cows), using indwelling pH meters, recording every 10 min for 14 days. Serum Hp was analysed in samples collected from 125 cows. No differences in ruminal pH or serum Hp concentration were found between treatment groups, or levels of feeding. It was concluded that, using ruminal pH patterns and Hp as markers of SARA at the feeding levels used in this study, there were no differences between grazing cows fed the supplement either as grain in the dairy or as a PMR fed on a feedpad.

A survey of northern Victorian dairy farmers to investigate dairy calf management: colostrum feeding and management: A survey of northern Victorian dairy farmers to investigate dairy calf management: colostrum feeding and management

Objectives To describe colostrum management practices carried out in northern Victorian dairy herds and to identify weaknesses in these areas that may affect calf health and welfare by comparing the results with the current industry recommendations Methods A questionnaire to obtain information about colostrum management and calf‐rearing practices was sent to commercial dairy farming clients of Rochester Veterinary Practice between June and September 2013. The questionnaire consisted of a general herd overview and colostrum harvesting practices. Results The response rate was 39% (58/150). Many dairy producers were not meeting the current industry recommendations in the following areas: (1) time of removal calf from the dam, (2) relying on calf suckling colostrum from the dam to achieve adequate passive transfer, (3) failing to supplement calves with colostrum, (4) feeding inadequate volumes of colostrum, (5) delayed colostrum harvesting, (6) pooling of colostrum, (7) failing to objectively assess colostrum quality or relying on visual assessment and (8) storing colostrum for a prolonged periods of time at ambient temperatures. Conclusion The results from this survey highlight the need for greater awareness of industry standards for colostrum management and feeding hygiene.

A survey of northern Victorian dairy farmers to investigate dairy calf management: calf-rearing practices: A survey of northern Victorian dairy farmers to investigate dairy calf management: calf rearing practices

OBJECTIVES To describe the calf-rearing practices carried out in northern Victorian dairy herds and to identify weaknesses that may affect calf health and welfare by comparing the results with current industry recommendations. METHODS Survey of dairy farms from Rochester and the surrounding farming area. RESULTS The response rate was 39% (58/150). Many dairy producers were not meeting the current industry recommendations in the following areas: (1) delayed access to pellets and roughage, (2) failing to provide access to water from birth, (3) delayed disbudding of calves, (4) delayed timing of booster vaccinations, (5) weaning based on age alone, (6) failing to isolate sick calves and (7) early sale age of excess calves. CONCLUSION The results from this survey highlight the need for greater awareness of industry standards for calf husbandry and weaning.