Effects of dietary supplementation with bile acids on production performance, egg quality, nutrient digestibility, and morphology of reproductive tract in late-laying hens.

The study investigated the effects of dietary supplementation with bile acids (BAs) on production performance, egg quality, nutrient digestibility, reproductive organ morphology, intestinal morphology, and blood parameters in late-laying hens. A total of 1080 Hy-Line Brown laying hens, each 76 weeks old, were randomly assigned to four groups receiving a basal diet supplemented with 0 (CON), 200 (BA200), 300 (BA300), or 500 (BA500) mg/kg BAs for 35 days, with 6 replicates per treatment and 45 hens per replicate. Results showed that dietary BAs supplementation increased laying rate, Haugh unit, albumen height, and yolk color in a linear and quadratic manner (linear and quadratic, P < 0.05), while decreasing the feed-to-egg ratio quadratically (quadratic, P < 0.05). The most pronounced improvements were observed in the BA300 group (P < 0.05). Dietary BAs supplementation significantly increased oviductal mucosal fold height, width, perimeter, and epithelial height, as well as uterine fold height and mucosal epithelial height (linear and quadratic, P < 0.05), with the most pronounced effects observed in the BA300 group (P < 0.05). Apparent nutrient digestibility increased significantly with increasing dietary BAs levels (linear and quadratic, P < 0.05). In particular, the BA300 group exhibited significantly higher apparent digestibility of dry matter, organic matter, crude protein, ether extract, gross energy, and arginine, lysine, methionine, threonine, valine, isoleucine, glutamic acid, and aspartic acid (P < 0.05). These improvements were accompanied by enhanced intestinal morphology and favorable changes in serum biochemical parameters, especially in the BA300 group. Overall, under the conditions of the present study, dietary supplementation with 300 mg/kg BAs produced the most pronounced beneficial effects across all measured parameters. These findings suggest that 300 mg/kg BAs may represent the optimal supplementation level and support the use of BAs as an effective nutritional strategy to alleviate performance decline in late-laying hens.