Dietary vitamin A supplementation improved reproductive performance by regulating ovarian expression of hormone receptors, caspase-3 and Fas in broiler breeders

Abstract

The effects of dietary vitamin A (VA) supplementation on reproductive performance, VA deposition, and potential mechanisms of action were studied in Chinese yellow-feathered broiler breeders. A total of 528 yellow-feathered broiler breeders that were 46 wk old were fed a corn–soybean meal basal diet supplemented with 0; 5,400; 10,800; or 21,600 IU/kg VA for 9 wk. Each dietary treatment had 6 replicates with 22 birds per replicate. After 7 wk of treatment, 60 settable eggs per replicate were collected for hatching. The results showed that dietary VA improved the laying rate, egg-to-feed ratio, and hatch weight of offspring (P < 0.05). Hepatic retinyl palmitate in broiler breeders and hatchlings (within 12 h) increased with increasing VA (P < 0.05). VA supplementation increased insulin-like growth factor 1 (IGF-I) receptor transcripts in the ovarian stroma and the walls of yellow follicles, follicle stimulating hormone (FSH) receptor expression in the walls of white and yellow follicles, and luteinizing hormone (LH) receptor and growth hormone (GH) receptor transcripts in the walls of yellow follicles (P < 0.05). Caspase-3 and Fas mRNA levels in the ovarian stroma and the walls of white and yellow follicles decreased with VA supplementation (P < 0.05). The relative expression of retinol dehydrogenase 10 (RDH10) transcripts in the walls of white follicles increased with 5,400 IU/kg VA supplementation (P < 0.05). Supplemental 21,600 IU/kg VA increased cytochrome P450 26A1 (CYP26A1) transcripts in the ovarian stroma and the walls of white follicles (P < 0.05). Dietary VA elevated retinoic acid receptor α (RARα) expression in the ovarian stroma and the walls of yellow follicles and retinoid X receptor α (RXRα) expression in the walls of yellow follicles. It was concluded that VA supplementation improved reproductive performance and hepatic storage of VA, and this was associated with the regulation of ovarian hormone receptor expression and suppression of apoptosis gene transcripts through its active metabolite retinoic acid (RA). The optimal dietary VA level for Chinese yellow-feathered broiler breeders at 46 to 54 wk of age was found to be 10,800 IU/kg.