Effects of periparturient vitamin A supplementation on vitamin A concentrations in colostrum and milk from dairy cows, and plasma retinol concentrations, feed intake and growth of their calves

Effects of periparturient vitamin A supplementation on vitamin A concentrations in colostrum and milk from dairy cows, and plasma retinol concentrations, feed intake and growth of their calves were studied. Eleven primiparous and 10 multiparous Holstein Friesian cows were assigned into one of three groups: 1) control; 2) 700,000IU/week of vitamin A supplemented in diet from 30 days before expected calving date; 3) 700,000IU/week of vitamin A supplemented in diet from 60 days before expected calving date. The supplementation was done by mixing with concentrate weekly and lasted until 45 days after calving. Calves were fed with colostrum provided from their own cows until 5 days and with whole milk until 45 days of age. All calves were fed with calf starter and Italian ryegrass hay ad libitum from 7 days of age. The supplementary vitamin A significantly increased vitamin A concentrations in colostrum and milk on 5, 15 and 45 days after calving. Primiparous cows had significantly higher vitamin A concentrations in colostrum and milk than multiparous cows on 1, 5 and 15 days after calving. No significant difference in plasma retinol concentrations of calves from cows among treatment groups was observed. The supplementation for cows had no significant effect on liveweight, daily gain and feed intake of their calves during 90 days after birth. Plasma retinol concentrations of calves on 90 days of age were positively correlated with daily gain and starter intake after weaning. Although 700,000IU/week vitamin A supplementation from 60 days or 30 days for cows before expected calving increased vitamin A concentrations in colostrum and milk, it had no effect on plasma vitamin A content and growth of their calves. It is suggested that calves ingested more calf starter had better liveweight gain and higher plasma retinol concentrations.