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

摘要

Calf preweaning morbidity and mortality risks havebeen reported as high in several countries, with averagevalues approximating 35 and 7%, respectively. However,limited data are available for calf morbidity andmortality risks on Australian dairy farms. The aims ofthis study were (1) to investigate current calf managementpractices on dairy farms in Australia and theirassociation with herd-level morbidity and mortalityusing a questionnaire-based, cross-sectional study; and(2) to estimate the prevalence of common enteropathogenscausing diarrhea, the failure of passive transferof immunity, and poor colostrum quality in a sampleof Australian dairy farms. We analyzed 106 completedquestionnaires and samples from 23 farms (202 fecal,253 calf serum, and 221 colostrum samples). Morbidityand mortality risks reported by farmers in preweanedheifers were 23.8 and 5.6%, respectively. These riskswere above the Australian dairy industry targets in75.5 and 66.7% of respondents. The zoonotic pathogensCryptosporidium spp. and Salmonella spp. were themost prevalent enteropathogens, with a true prevalenceof 40.9 and 25.2%, respectively. Salmonella O-group Dwas present in 67.9% of Salmonella-positive samples,followed by O-groups B (17.9%) and C (10.7%). Failureof transfer of passive immunity (IgG <10 g/L) was observedin 41.9% of calves (mean herd-level prevalenceof 36.2%), and only 19.5% of colostrum samples metthe standards for immunoglobulin content and microbiologicalquality. Collectively, these data indicatethat there is still considerable room for improvementin calf-rearing practices on Australian dairy farms,particularly with regard to colostrum management andfeeding hygiene.