Effect of Parenteral Administration of Vitamin A in Dairy Cattle During Dry Period, on Vitamin A Status of Neonatal Calves

The present study has been conducted to evaluate the effect of intramuscular administration of vitamin A during dry period in pregnant dairy cows which have already received it in their daily ration on vitamin A status of neonatal calves.Single intramuscular injection of 2000000 IU vitamin A was carried in 10 dairy cows at 7 months of pregnancy (group 1) and in another 10 dairy cows at 8 months of pregnancy (group 2). Ten pregnant dairy cows received saline injection as placebo and were selected as the control group. Blood samples were collected from dairy cows at 7 and 8 months of pregnancy as well as their newborn calves’ pre and after colostrum intake.Vitamin A concentration of calves of two treatment groups before and after receiving of colostrum were significantly higher than that in control group (P<0.05). Daily supplementation of vitamin A in late pregnancy in dairy cows may not compensate for the calves need for vitamin A and single injection of this vitamin A during dry period either in 7 or 8 month of pregnancy can significantly increase level of vitamin A in their neonatal calves.