An investigation of dairy calf management practices, colostrum quality, failure of transfer of passive immunity, and occurrence of enteropathogens among Australian dairy farms

Abstract

Calf preweaning morbidity and mortality risks have been reported as high in several countries, with average values approximating 35 and 7%, respectively. However, limited data are available for calf morbidity and mortality risks on Australian dairy farms. The aims of this study were (1) to investigate current calf management practices on dairy farms in Australia and their association with herd-level morbidity and mortality using a questionnaire-based, cross-sectional study; and (2) to estimate the prevalence of common enteropathogens causing diarrhea, the failure of passive transfer of immunity, and poor colostrum quality in a sample of Australian dairy farms. We analyzed 106 completed questionnaires and samples from 23 farms (202 fecal, 253 calf serum, and 221 colostrum samples). Morbidity and mortality risks reported by farmers in preweaned heifers were 23.8 and 5.6%, respectively. These risks were above the Australian dairy industry targets in 75.5 and 66.7% of respondents. The zoonotic pathogens Cryptosporidium spp. and Salmonella spp. were the most prevalent enteropathogens, with a true prevalence of 40.9 and 25.2%, respectively. Salmonella O-group D was present in 67.9% of Salmonella-positive samples, followed by O-groups B (17.9%) and C (10.7%). Failure of transfer of passive immunity (IgG <10 g/L) was observed in 41.9% of calves (mean herd-level prevalence of 36.2%), and only 19.5% of colostrum samples met the standards for immunoglobulin content and microbiological quality. Collectively, these data indicate that there is still considerable room for improvement in calf-rearing practices on Australian dairy farms, particularly with regard to colostrum management and feeding hygiene.

Quantitative Analysis of Colostrum Bacteriology on British Dairy Farms

“…Of 268 NZ samples taken of pooled colostrum, 91 and 91% failed for TBC and CC, respectively (16). Of 221 Australian colostrum samples, 42 and 28% of samples failed on TBC and CC, respectively, with only 20% meeting both standards for immunoglobulin (>50 g/L) and microbiological quality (17), reinforcing previous Australian studies which found 42 and 6% of samples exceeded TBC and CC, respectively, with only 23% meeting all standards for TBC, CC and immunoglobulin levels (18). Previous studies examining colostrum bacteriological levels in Irish dairy herds reported 57% of 214 samples exceeding TBC and 33% exceeding CC thresholds, with significant variation between farms (9), however, there have been no published studies on colostrum hygiene levels on GB dairy farms to date.…”

Linear body measurements and productivity of subtropicalHolstein–Friesiandairy calves

“…These findings are consistent with previous reports. 11 In the current study, on average, the estimated total LW loss with a single pneumonia event was 14.6 kg ( Figure 1). This trend is in agreement with previous findings where calves with episodes of the respiratory disease had a significant reduction (8.2 kg) in carcass weight.…”

“…1,7,20 These growth rates varied depending on nutritional factors 7,27 and disease incidence. 11 A study by Johnson et al described how feeding policies and other risk factors impacted the growth rate on 492 UK calves. 36 The study reported that ADG varied between farms from 0.52 to 0.75 kg/day depending on how much milk was fed, the presence of for the fortnight prior to disease event, 1 level for the fortnight of the confirmed disease event, levels 2-4 are for the three fortnights (maximum number of fortnights until weaning assuming a calf was observed with an even on the first fortnight) after disease event fortnight.…”

“…45 The reported factors that have been found to predispose calves to respiratory disease include: birth season, nutrition, age, mixing, shared feeding devices, housing type, bedding and failure of passive transfer of immunity. 11,12,46 Therefore, in order to safeguard future productivity, it is important to recognise these factors and prevent respiratory disease. In this study, observed cases of diarrhoea were not associated with the loss of LW (Table 5).…”

“…They also determined that calves had a respiratory disease morbidity of 18% (SD = 15%) with a neonatal calf diarrhoea morbidity of 6% (SD = 8%) in preweaned heifers. 11 Respiratory disease has been reported to significantly reduce liveweight (LW) gain and linear body measurements. 12,13 It was estimated that bovine respiratory disease (BRD) costs a dairy farm between USD 15 and 49 per calf per year.…”