부산대학교 도서관

Little is known about transfer of dietary β-carotene into colostrum, its absorption by the calf, and its effects on vitamins A and E in the cow when dietary vitamin A is adequate. Our objective was to assess the impact of β-carotene supplementation during the close-up dry period on the cow, 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 assigned to either control (CON) or β-carotene (BC) treatments. While locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 d before expected calving (before treatments began), 7 d before calving, immediately following parturition, and 7 d postpartum. Colostrum was collected immediately following 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 vitamins A and E, cholesterol, and β-carotene. Colostrum was analyzed for β-carotene, vitamins A and E, and colorimetry profile. Data were assessed using the MIXED procedure in SAS. Calf serum β-carotene data were analyzed using the FREQ procedure. Compared with CON cows, BC cows had higher concentrations of β-carotene (P< 0.01), vitamin A (P< 0.01), and vitamin E (P< 0.01), and a greater vitamin E:cholesterol (P< 0.01) in serum at all times. Colostrum β-carotene was higher for BC cows (P< 0.01). Colostrum from BC cows had increased a* (P< 0.01) and b* (P< 0.01) colorimeter values, indicating that β-carotene altered colostrum color. Before receiving colostrum, the concentration of β-carotene in calf serum was below the detectable threshold of 0.05 ug/mL. At 24 h of age, the number of calves with detectable β-carotene concentrations increased, with more calves from BC cows (52.1%) having detectable concentrations than calves from CON cows (6.1%, P< 0.01). No differences in concentrations of vitamins A or E were observed in calves. In pregnant cows already receiving adequate vitamin A, supplementation of β-carotene increased concentrations of β-carotene, vitamin A, and vitamin E, increased concentration of β-carotene in colostrum, and increased serum β-carotene in calves.