Aims: To determine the prevalence of failure of passive transfer (FPT) of maternal antibodies, to identify management factors associated with FPT, and to determine the relationship between interval from the start of calving and calf management practices on concentrations of total protein in the serum of calves, from a sample of spring-calving dairy herds in the Manawatu region of New Zealand.
Methods: This was an observational study involving 11 dairy farms in the Manawatu region serviced by Massey University Farm Services Clinic. Blood samples were collected from calves <1-week-old during August and September 2012 and concentration of total protein in serum was assessed by refractometry. FPT was defined as concentrations of total protein in serum ≤50 g/L. A questionnaire on early calf rearing practices was completed on each farm. Linear mixed and generalised linear mixed models were used to determine associations with concentrations of total protein in serum and risk of FPT.
Results: The mean concentration of total protein in serum for the 230 samples collected was 60.6 (SE 0.93) g/L and 57/230 (24.8 (95% CI=19.3‒30.9)%) calves were diagnosed with FPT. Two variables, days from planned start of calving to when the calf was sampled, and reportedly feeding colostrum for the first 4 days post-partum, were associated with increased concentrations of total protein in serum (p<0.05). There was also an association between the odds of FPT for calves sampled in a particular week and the proportion of the total herd calving in that same week (p<0.005).
Conclusions and clinicial relevence: Feeding colostrum for 4 days from birth and increasing days from planned start of calving to calf sampling were associated with increased concentrations of total protein in serum. FPT on the surveyed farms appeared to be associated with an inability to adequately manage the total number of new born calves during the busiest period of calving.
Keywords: Calf; colostrum; failure of passive transfer; maternal immunity; risk factor.