Dietary Fermented Strawberry Pomace Improves Yolk Lipid Quality and Modulates Reproductive Endocrine Activity, Intestinal Barrier Status, and Cecal Microbiota in Laying Hens

Strawberry pomace is a fruit processing by-product rich in fiber and bioactive compounds, making it a functional feed resource. This study evaluated the effects of fermented strawberry pomace (FSP) on laying performance, yolk fatty acid composition, ovarian function, intestinal barrier status, cecal microbiota, and short-chain fatty acids (SCFAs) in laying hens. A total of 320 laying hens (345-day-old) were assigned to diets containing 0, 0.25, 0.5, or 1.0% FSP for 8 weeks. Supplementing 0.25% FSP increased albumen height and Haugh unit (p < 0.05). In addition, 1.0% FSP reduced yolk saturated fatty acids and thrombogenic index and increased the polyunsaturated-to-saturated fatty acid ratio (p < 0.05). Dietary FSP supplementation enhanced reproductive endocrine activity by increasing plasma and ovarian hormones, whereas 0.25% FSP upregulated HSD17B1 and LHCGR expressions (p < 0.05). Dietary 1.0% FSP upregulated ovarian Nrf2 and SOD1 expressions, whereas 0.5% FSP improved small-intestinal morphology and upregulated intestinal barrier-associated gene expressions, including Occludin, Cadherin 1, and Mucin 2 (p < 0.05). Moreover, 0.5% FSP increased cecal microbial richness, reshaped microbial composition, and 0.25–1.0% FSP supplementation increased the molar proportion of acetic acid but decreased absolute acetic acid and total SCFAs concentrations (p < 0.05). In summary, dietary FSP improved yolk lipid nutritional quality, particularly at 1.0% supplementation. FSP supplementation also affected reproductive endocrine activity, intestinal barrier-related status, and cecal microbial fermentation.