INFLUENCE OF CALF GENOTYPE ON COLOSTRAL IMMUNOGLOBULINS IN BOS-TAURUSAND BOS-INDICUS COWS AND SERUM IMMUNOGLOBULINS IN THEIR CALVES

Purebred Bos indicus calves are documented to have lower survival rate s than Bos taurus calves. Thus, this study was designed to investigate the possibility that this decreased survival rate may be attributed t o dam colostral immunoglobulin (Ig) concentrations and subsequent calf serum Ig concentrations. The specific objective was to determine the effect of breed type of calf on colostrum production, immunoglobulin c oncentrations in colostrum and calf serum, and availability and absorp tion efficiency of Ig. Brahman (B) and Angus (A) cattle were reciproca lly mated to produce calves of the following types: A x A (n = 8), A x B (n = 9), B x B (n = 11), and B x A (n = 11). At birth, calves were separated from their dams and a blood sample was collected before feed ing pooled colostrum (30 mL/kg birth weight) at 1 and 6 h of age. From 6 to 12 h of age, each calf was placed in a box that allowed interact ion with the dam but prevented suckling. At 12 h of age, each calf was fed its dam's colostrum and placed with the dam. Additional blood sam ples were collected at 12, 24, and 48 h after birth. Serum and colostr um samples were analyzed for IgG, IgG(1), IgG(2), IgM, and IgA using s ingle radial immunodiffusion (RID) assay techniques. The cows were han d-milked after induction of milk letdown with oxytocin at 1 and 12 h a fter calving. Colostrum volume was recorded, and samples were collecte d. Brahman cows produced more (P < .001) colostrum at 1 and 12 h than A cows. Total Ig concentrations were obtained by summing IgG, IgG(1), IgG(2), IgM, and IgA concentrations. Total Ig (P < .02), IgG (P < .005 ), and IgA (P < .01) concentrations in colostrum were greater in cows producing crossbred calves. Total Ig (P < .006), IgG (P < .02), IgG(1) (P < .004), and IgG(2) (P < .02) available in colostrum were affected by B x B and A x B breed types of calf. Brahman cows had more Ig avai lable at 1 and 12 h than A cows due to increased production of colostr um. Breed type influenced colostral Ig in cattle. Serum concentrations of total Ig, IgG, IgG(1), IgG(2), IgM, and IgA in the calf and effici ency of absorption at 6 and 12 h were not affected by breed type, sex of calf, or any interaction.