Variation in serum concentrations of immunoglobulins G, A, and M in Canadian Holstein-Friesian calves.

Radial immunodiffusion was used to quantify Ig concentrations (mg/100 ml) in the sera of 74 male and 82 female Holstein calves and in whole colostrum from their dams. Calves were the progeny of 15 AI bulls. Blood samples were collected by jugular puncture from calves at birth, 24 to 36 h post first colostrum ingestion, and then weekly from 3 to 7 wk of age. Colostrum was sampled within 6 h of parturition. Mean calf serum Ig profiles showed peak concentrations of all isotypes by d 1 of age, which declined greatly by 3 to 4 wk, followed by gradual increases to 7 wk. Within isotype, there were highly significant positive correlations between serum concentrations in calves from 3 to 7 wk and between colostral and calf serum concentrations up to 5 wk, depending on isotype. Effects of season and location on calf serum isotype concentrations were important, but effects of ease of calving and twinning were small. Paternal half-sib heritability estimates computed by restricted maximum likelihood ranged from 0 to .20 for IgG, 0 to .45 for IgA, and 0 to .26 for IgM, depending on sampling period, and were .07, .08, and 0 for IgG, IgA, and IgM, averaged over all sampling periods. Although standard errors were large, heritability estimates for passive (24 to 36 h) and onset of active (3 to 4 wk) immunity suggested a moderately important additive genetic component and that these serum Ig concentrations could possibly be manipulated to produce more disease-resistant dairy calves.