Vitamin A supplementation effects during late-stage pregnancy on longissimus dorsi muscle tissue development, birth traits, and growth performance in postnatal Korean native calves

Objective: This study investigated the effects of vitamin A (VA) supplementation during late pregnancy on longissimus dorsi muscle tissue development, birth traits, and growth performance in postnatal Korean native calves. Methods: In the preliminary experiment, twenty-six pregnant cattle [initial BW=319 kg (SD=30.1); 1st parity] were randomly assigned to the control and treatment group. Vitamin A supplementation at 24,000 IU/day was supplied to the treatment group from gestational day 225 to delivery. In the main experiment, twelve pregnant cattle [initial BW=317 kg (SD=31.3); 1st parity] were used and were treated with VA supplementation at 24,000 IU/day (gestational days 150-225) and at 78,000 IU/day (gestational day 225 to delivery). Serum VA in pregnant cattle, growth performance, gene expression, and serum VA were analyzed in the offspring calves. Results: Serum VA in pregnant cattle decreased during the late gestation in both experiments (p<0.001). In the main experiment, treatment group showed higher serum VA than control in pregnant cattle at the time of parturition and offspring at birth (p<0.05). Higher birth weight was observed in the main experiment (p=0.022) and tendency (p=0.088) in the preliminary experiment in the treatment group. However, no differences were observed in feed intake, ADG, G:F, and BW of 31-day-old calves. Gene expression was analyzed in the longissimus dorsi muscle of 31-day-old calves. Vitamin A supplementation in pregnant cattle stimulated postnatal muscle development by elevating Myf5, Myf6, and MyoD (p<0.05). Moreover, preadipocyte-related marker genes such as ERK2 and KLF2 were higher in the treatment group than in the control group (p<0.05). Conclusion: 78,000 IU/day VA supplementation to late pregnant cattle maintains serum VA levels. In addition, 78,000 IU/day VA supplementation enhances birth weight and gene expression-related muscle and preadipocyte development in offspring. Overall, 78,000 IU/day VA supplementation to pregnant cattle would be beneficial to newborn calves.