RESUMO
OBJECTIVES: To determine the prevalence of failure of transfer of passive immunity (FTPI) and agammaglobulinaemia in calves in south-west Victorian dairy herds and identify associated risk factors for both outcomes. DESIGN: Cross-sectional study. METHODS: Serum total protein was measured in 1018 calves from 100 south-west Victorian dairy herds. The proportions of calves with FTPI and agammaglobulinaemia were determined and logistic regression with random effects used to identify calf- and herd-level variables associated with both conditions. RESULTS: In total, 38% of calves had FTPI and 8% of calves had agammaglobulinaemia. Two-thirds of herds had more than 25% of calves with FTPI. Jersey and Jersey-cross calves were less likely than Holstein-Friesian calves to have FTPI (odds ratio (OR) 0.53 and 0.57, respectively). Dairy-beef crossbreed calves were more likely to have agammaglobulinaemia than Holstein-Friesian calves (OR 3.52) and bull calves were more likely to have agammaglobulinaemia than heifer calves (OR 2.22). Removal of calves from the calving area less than twice a day was associated with increased odds of FTPI (OR 1.61) and agammaglobulinaemia (OR 1.97) relative to more frequent removal. CONCLUSION: There is considerable potential to improve the transfer of passive immunity in dairy herds in south-west Victoria. The prevalence of both FTPI and agammaglobulinaemia is likely to be reduced by collecting calves from the calving area twice daily and hand-feeding them extra colostrum immediately after their removal from the calving area.