Genetic differences in concentration of immunoglobulins G1 and M in serum and colostrum of cows and in serum of neonatal calves.

Blood samples obtained 24 and 36 hr postparturition from 187 calves in 2 years were analyzed for serum concentration of immunoglobulins G1 (IgG1) and M (IgM). Serum and colostrum samples also were obtained from their dams, and corresponding immunoglobulin levels were determined. Calves were evaluated for their ability to acquire and absorb immunoglobulins and cows for their ability to produce immunoglobulins. Mathematical models included sources of variation for breed of sire, sire within breed, breed of dam, age of dam and sex of calf. Of these factors, breed of sire, breed of dam and age of dam were the most important. Simmental- and Pinzgauer-sired calves tended (p = .07) to have lower IgG1 and IgM levels than calves sired by Hereford, Hereford X Angus and Tarentaise bulls. Calves of Hereford X Angus dams had consistently higher immunoglobulin concentrations than calves of Hereford dams. Hereford X Angus cows tended to have higher colostrum concentrations and lower serum concentrations of the two immunoglobulins than Hereford cows. A fetal sire effect was demonstrated for serum IgM concentrations in that cows mated to Simmental bulls had lower (P = .05) concentrations than cows mated to bulls of other breeds. Advancing age of dam was associated with higher concentrations of immunoglobulins, except for serum IgM in the calf and in the cow. Correlations between serum and colostrum concentrations of both immunoglobulins in the dam were low, as were correlations between cow colostrum concentration and calf serum concentration of IgG1. IgM in the colostrum was positively associated with IgM in calf serum, however. Heritability estimates for calf serum IgG1 concentration were high (.52 +/- .28 and .69 +/- 30 at 24 and 36 hr, respectively), while estimates for heritability of IgM concentrations were intermediate (.30 +/- .26 and .35 +/- .26 at 24 and 36 hr, respectively). There was no evidence that sires within breeds influenced, through the fetus, immunoglobulin concentrations in serum or colostrum of their mates. Relatively high repeatabilities for all traits imply that observed differences among cows were due in part to genetic and (or) permanent environmental differences.