Comparative Efficacy of Selenium Yeast Supplements on the Health and Productivity of Commercial Layers.

This study was conducted to evaluate the comparative efficacy of graded levels of dietary organic selenium (OS) on the health, productivity, and egg quality of commercial laying hens. A total of 240 hens (26 weeks old) were randomly allotted to four dietary treatments in a completely randomized design: a control basal diet (0 ppm OS) and three diets supplemented with OS from selenium yeast (SY-2000 or SY-3000) to achieve levels of 0.20, 0.30, and 0.45 ppm, respectively. The experiment lasted for 72 days. Performance metrics were recorded weekly, and samples were collected at two time points to assess physiological responses. The results demonstrated that supplementation with 0.30 and 0.45 ppm OS significantly improved key productivity parameters. Egg production (p < 0.05), egg weight (p < 0.001), and cumulative egg mass (p < 0.001) were higher in these groups compared to the control. Nutrient digestibility, including dry matter, crude protein, and ether extract, was also significantly enhanced (p < 0.001) at the higher OS levels. The antioxidant defense system was strengthened, as evidenced by the increased serum activity of the glutathione peroxidase (p < 0.001), superoxide dismutase (p < 0.01), and diphenyl picrylhydrazyl radical scavenging capacity (p < 0.05). Furthermore, the humoral immune response against Newcastle disease showed a significant, dose-dependent improvement (p < 0.001). In contrast, feed intake, various egg quality parameters (shell thickness, specific gravity, and Haugh unit), and serum mineral profiles remained unaffected (p > 0.05) by OS supplementation. In conclusion, dietary OS supplementation at 0.30-0.45 ppm effectively enhances laying performance, nutrient utilization, systemic antioxidant capacity, and specific immunity, with the 0.45 ppm level demonstrating the most consistent and comprehensive benefits under the conditions of this study.