Effects of Dietary Sterol-Enriched Yeast Hydrolysate on Ovarian Development, Reproductive Endocrine Status, Immune-Inflammatory Responses, Antioxidant Indices, and Egg Quality in Late-Laying Yellow-Feathered Broiler Breeder Hens

Abstract

Simple Summary Late-laying broiler breeder hens often show declining reproductive performance. This study evaluated dietary sterol-enriched yeast hydrolysate (SYH; 0, 0.2, 0.5, or 0.8 g/kg) in 720 hens over a six-week feeding period. The 0.5 g/kg treatment improved eggshell strength and was associated with the highest ovarian index and the greatest quantities of 5–12 mm yellow follicles. In contrast, 0.8 g/kg elicited the strongest endocrine and immune responses but also the highest increases in oxidative and inflammatory markers. Hepatic and ovarian SOD activity increased selectively, whereas fertility and hatchability were unaffected. Under the conditions of this study, 0.5 g/kg provided the most balanced response and should be considered a candidate inclusion concentration for further validation.