PSXIV-30 - Effects of vitamin/mineral supplementation during gestation in beef heifers on immunoglobulin concentrations in colostrum and immune responses in naturally and artificially reared calves

Abstract: Two experiments were conducted to evaluate the impacts of feeding a vitamin/mineral supplement to beef heifers throughout gestation on concentrations of immunoglobulin (Ig) in colostrum and in calf serum 24 h after consumption of maternal colostrum (Exp. 1) or a colostrum replacement product (Exp. 2). Angus-based beef heifers (n=72, initial body weight [BW] = 380.4 ± 50.56 kg) were managed in an individual feeding system and randomly assigned to a basal diet targeting gain of 0.45 kg/heifer/day (CON; n = 36) or the basal diet plus 113 g•heifer^-1•d^-1 of a vitamin/mineral supplement (VTM; n = 36). For Exp. 1 treatments began at the time of artificial insemination (AI) to sexed semen, and heifers becoming pregnant after first service AI (CON, n = 14; VTM, n = 17) continued treatments throughout gestation. At calving, heifer calves were allowed to nurse their dams and remained alongside their dams until weaning. For Exp 2. non-pregnant heifers were rebred 60 d after initial dietary treatments began and continued treatments throughout gestation, with resultant heifer calves (CON, n = 7; VTM, n = 7) being removed from their dams at birth and receiving 1.5 L of colostrum replacer containing 150 g globulin protein via an esophageal feeder, followed every 12 h by 1.9 L of milk replacer. In both experiments samples of colostrum were collected after completely milking the rear-right quarter of the udder. Blood samples were collected from calves before (within 2 h of birth) and 24 h after colostrum consumption. Concentrations of IgG, IgM, and IgA were quantified in colostrum and serum via bovine radial immunodiffusion plates. Data for both experiments were analyzed for the effect of treatment using the MIXED procedure in SAS, with additional analysis of data from Exp. 1 using the CORR procedure to determine correlations among dam colostrum and calf serum Ig concentrations at 24 h. In both experiments, maternal treatment did not affect (P ≥ 0.21) concentrations of IgG, IgM, or IgA in colostrum at calving or in calf serum at 24 h. All calves from both experiments had undetectable concentrations of these respective immunoglobulins at birth. Concentrations of IgG at 24 h in calves that received maternal colostrum were 2595.8 ± 535.38 mg/dL (Exp. 1), whereas those that received colostrum replacer were 1610.6 ± 335.09 mg/dL (Exp. 2). Concentrations of IgG, IgM, and IgA were positively correlated (r ≥ 0.34; P ≤ 0.05) with concentrations of calf serum IgG, IgM, and IgA at 24 h after suckling. Our results suggest that maternal vitamin/mineral supplementation throughout gestation did not impact Ig concentrations in colostrum or the resultant serum Ig concentrations in calves either 24 h after suckling or after delivery of a commercial colostrum replacer.