Genetic parameters of colostrum and calf serum antibodies in Swedish dairy cattle

Background Colostrum with sufficient IgG content is essential for the newborn calf, as it provides passive immunity which substantially affects the probability of survival during rearing. Failure of passive transfer occurs when a calf does not absorb enough antibodies from the colostrum as indicated by less than 10 g/L of IgG in calf serum. Besides delayed access to colostrum, this can be due to low IgG production of the mother or poor IgG absorption by the calf. The aim of this study was to estimate the genetic background of antibody levels and indicator traits for antibodies in colostrum and calf serum, and their correlation with milk production and health. Results Colostrum data were available from 1340 cows with at least one calving and calf serum data were available from 886 calves from these cows. Antibody concentrations were estimated using refractometry (digital Brix refractometer for colostrum and optical refractometer for serum) as indicator traits and established using ELISAs to determine total IgG and natural antibodies [NAb] of various antibody isotypes in colostrum and serum. Colostrum traits had heritabilities ranging from 0.16 to 0.31 with repeatabilities from 0.21 to 0.55. Brix had positive genetic correlations with all colostrum antibody traits including total IgG (0.68). Calf serum antibody concentrations had heritabilities ranging from 0.25 to 0.59, with a significant maternal effect accounting for 17 to 27% of the variance. When calves later in life produced their first lactation, lactation-average somatic cell score was found to be negatively correlated with NAb in calf serum. Conclusions Our results suggest that antibody levels in colostrum and calf serum can be increased by means of selection.