Feeding colostrum based on birth weight improves dairy calves’ passive immunization

Abstract

Calves are born agammaglobulinemic, and thus, they need an adequate volume of colostrum right after birth. Good quality colostrum can be limited in a dairy farm, depending on several environmental and management factors. Also, the right amount of colostrum that a calf should consume is not entirely defined. In this work, we aimed to study the effect of the volume of colostrum fed by kg of birth weight (BW) in the passive immune transfer of dairy calves. The BW of 30 dairy calves (n=24 Friesian; n=6 cross-Friesian) and the volume of colostrum fed per kg of BW (VOL/kg) in the first 24h were recorded from 2 dairy farms. Blood samples were collected from the calves’ jugular vein 24 hours after birth for serum total protein (STP) analysis by refractometry; failure of passive immune transfer (FPIT) was considered with STP<5.8 g/dL. GLM and a Non-parametric test (Kruskal-Wallis’s test) were used to check for differences in BW, VOL/Kg and STP across factors (Farm, Breed and Sex). Two groups were computed based on the BW mean (Light≤41.8 kg<Heavy), and its effect on the STP was tested with Welch’s ANOVA. Odds Ratio (OR) analysis was used to study if VOL/kg and FPIT were independent. The mean BW, VOL/kg and STP were, respectively, 41.84±4.60 kg, 8.9±3.5% (4 to 22%) and 6.10 g/dL. Breed had a significative effect on BW and STP, whilst farm also influenced VOL/kg. Heavier calves had a lower concentration of STP than lighter calves (5.63±0.35 and 6.33±0.98 g/dL, respectively; P=0.018). STP concentration was statistically higher in calves fed with a higher VOL/kg. OR analysis showed that VOL/kg under 8% increased 7 times (OR 7; 95% CI 1.365-35.929) the likelihood of occurring FPIT. No absorptive limit regarding the volume of colostrum administered by kg of BW was found, as it has been shown in previous literature. Heavier calves should consume more colostrum than lighter calves and not a management-based standardized volume.