Dietary evaluation of Pleurotus ostreatus spent mushroom substrate on productivity, nutrient digestibility, egg quality, antioxidant status, and ovarian cytoprotective responses in laying hens

This study evaluated the dietary inclusion level effects of Pleurotus ostreatus spent mushroom substrate (SMS) on performance, nutrient digestibility, egg quality and oxidative stability in laying hens. Additionally, key ovarian homeostasis-related genes involved in detoxification (aryl hydrocarbon receptor-AhR), antioxidant (nuclear factor erythroid 2-related factor 2-Nrf2), and inflammatory response (nuclear factor kappa B-NF-κB) were assessed. A total of 196 Hy-Line Brown hens, 51-weeks of age, were assigned to 4 treatments with 7 replicates of 7 hens each, receiving isocaloric, isonitrogenous and isofibrous diets containing 0 (S0), 25 (S25), 50 (S50), or 100 (S100) g SMS/kg. Performance responses were determined weekly throughout the 7-week experimental period and are reported as overall. At the end of week 7, eggs were collected for quality and oxidative stability determination, and ovarian samples were obtained for qPCR analysis. Increasing SMS inclusion level, improved overall laying rate and egg mass, with optimal (P ≤ 0.05) performance notable in the S100 compared to S0, and enhanced ether extract digestibility (P < 0.01). Egg oxidative stability was significantly improved by SMS inclusion, as reflected by reduced yolk malondialdehyde and egg-white protein carbonyl levels in fresh and stored eggs (P ≤ 0.001), with the lowest values consistently observed in the S100 treatment. The nutrigenomic analyses revealed that dietary SMS inclusion beneficially modulated (P ≤ 0.05) the majority of ovary-expressed genes related to detoxification (AhR pathway; 3/4 genes), antioxidant defense (Nrf2 pathway; 5/9 genes), and inflammatory response (NF-κB pathway; 8/13 genes), with the most pronounced differences observed in the S100 treatment compared with the control treatment. Conclusively, dietary SMS inclusion at 100 g/kg enhanced layer performance, improved ether extract digestibility, and increased egg oxidative stability. In addition, nutrigenomic analyses revealed that the observed improvements in performance and egg quality were supported by beneficial modulation of key homeostasis-related genes relevant to ovarian function and health.