Effects of prepartum supplementation of ?-carotene on colostrum and calves

Little is known about transfer of dietary 0-carotene into colostrum, its absorption by the calf, and its ef-fects on retinol and alpha-tocopherol in the calf when the dam's dietary vitamin A is adequate. Our objective was to assess the effect of 0-carotene supplementation during the close-up dry period on the colostrum and calf. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were blocked by calving data, parity, and previous production, and then randomly assigned to either control or 0-carotene (BC) treatments. While locked in headgates each morning, each cow received a topdress of 0-carotene (Rovimix, DSM Nutritional Products, 8 g/d; provided 800 mg 0-carotene) or carrier from 21 d before expected calv-ing until calving. Colostrum was collected within 2 h of parturition. Calf blood samples were obtained within 2 h of birth before receiving the dam's colostrum, at 24 h after birth, and at 7 d and 60 d of age. Blood serum was analyzed for 0-carotene, retinol, alpha-tocopherol, and other metabolites and enzymes. Colostrum was ana-lyzed for 0-carotene, retinol, alpha-tocopherol, colorimetry profile, and milk components. Data were analyzed us-ing mixed-effects models in SAS (SAS Institute Inc.). Calf serum 0-carotene data were analyzed using the FREQ procedure. Colostrum 0-carotene was higher for BC cows. Colostrum from BC cows had increased a* [measures red (positive) to green (negative)] and b* [measures yellow (positive) to blue (negative)] colorimeter values, indicating that 0-carotene altered colostrum color toward red and yellow. Supplementa-tion did not affect colostral or calf IgG concentrations. Colostrum color indices were correlated with IgG concentrations as well as concentrations of 0-carotene, retinol, and alpha-tocopherol. Before receiving colostrum, the concentration of 0-carotene in calf serum was below the detectable threshold of 0.05 mu g/mL. At 24 h of age, the number of calves with detectable 0-carotene con-centrations increased, with more calves from BC cows (52.1%) having detectable concentrations than calves from cows in the control group (6.1%). No differences in concentrations of retinol or alpha-tocopherol were ob-served in calf serum. Supplementation of 0-carotene to cows decreased activities of gamma-glutamyl transpep-tidase and glutamate dehydrogenase in calf serum. In pregnant cows already receiving adequate vitamin A, supplementation of 0-carotene increased concentration of 0-carotene in colostrum, altered colostrum color, and increased serum 0-carotene in calves at birth.