PSXVII-29 Effects of vitamin A supplementation in late-pregnancy cow diets on tissue development and birth traits in calves.

Abstract

The objective of this study was to determine the effects of vitamin A (VA) as a supplementation to the diet of cows in late pregnancy on tissue development and birth traits in Korean native calves. In study 1, a VA supplementation at 24,000 IU per day was supplied to a high-VA group (n = 8) from 225 days in gestation to delivery. In study 2, pregnant cows treated with a high level of VA (n = 5) consumed a VA supplementation at 24,000 IU in period 1 (from 150 to 225 days in gestation). In period 2 (from 225 days in gestation to delivery), the treatment diet contained a VA supplementation of 78,000 IU per day. The level of serum VA of pregnant cows decreased as the day of delivery approached, both in the groups in study 1 and in study 2 (P P = 0.01). The level of serum VA of the offspring of pregnant cows fed the high levels of VA also increased by 28.6% (P = 0.033) compared to the control. In study 1 and 2, birth weight of calves in the high-VA group was heavier than the control. We found that the gene expression related muscle development (MyoD, Myf5, Myf6, MyoG, PPARγ, and LPL) tended to increase in the 31-day-old calf among pregnant cows treated with high levels of VA (P < 0.1). However, there were no significant differences either in the early or late adipogenic marker genes (ZFP423, ERK2, KLF2, FABP4, SCD) excluding C/EBPα. We suggest that supplementation of VA at 78,000 IU per day kept the level of serum VA from dropping in late-gestation cows and a sufficient level of VA could enhance both birth weight and muscle development marker genes in the pregnant cows’ offspring, contributing to increased productivity in the calf.