Determination of immunoglobulin concentrations and genetic parameters for colostrum and calf serum in Charolais animals
Résumé
Colostrum samples from 366 Charolais primiparous cows, as well as serum from their calves at 24 to 48 h of age, were collected to gain an overview of the situation regarding passive immune transfer in beef cattle, from both the phenotypic and genetic points of view. All samples were analyzed to quantify their G1 immunoglobulins by radial immunodiffusion (RID) and their IgG, IgA, and IgM using ELISA. The average concentrations obtained in colostrum were 84 mg/mL for RID-IgG1, and 158 mg/mL, 4.5 mg/mL and 10.8 mg/mL for ELISA-IgG, -IgA, and -IgM, respectively. The corresponding values in calf serum were 19.9, 30.6, 1.0, and 1.9 mg/mL. Apart from the general environmental effect (farm-year combination and laboratory conditions), the characteristics of the dams tested did not reveal any influence on colostrum immunoglobulin concentrations. Calving difficulty, as well as the birth weight and sex of calves, were found to be associated with serum concentrations in some cases. Heritability estimates were low to moderate, with the highest being for RID-IgG1 in colostrum (h2 = 0.28, standard error = 0.14) and serum (h2 = 0.36, standard error = 0.18). Phenotypic correlations among the different immunoglobulins were generally positive or null, and none of the genetic correlations were significant due to large standard errors. The phenotypic correlation between dam colostrum and calf serum values was 0.2 for RID-IgG1 and null for the 3 ELISA measurements. The correlation between RID-IgG1 and ELISA-IgG was, unexpectedly, null for colostrum and 0.4 for serum. Increased RID-IgG1 levels in calf serum were associated with improved survival, as well as better early growth and fewer health problems. These results thus showed that despite generally higher concentrations in beef than in dairy cattle, passive transfer was unsuccessful in a considerable number of calves. This should be brought to the attention of breeders to avoid negative effects on survival and subsequent performance. The heritability estimates were encouraging; however, obtaining phenotypes on a large scale constitutes a real limitation regarding these traits.
