Selenium yeast improves egg production performance by increasing antioxidant capacity, reproductive hormone levels and yolk precursor synthesis in late peak laying hens

This study investigated the effects of dietary SY to supplementation on the production performance, reproductive hormones, antioxidant capacity and yolk precursor synthesis in laying hens during the late peak laying period. A total of 448 Hy-Line Brown hens (50 weeks old) were randomly assigned to four groups (basal diet supplemented with 0,0.15,0.30, and 0.45 mg/kg SY) with 7 replicates per treatment and 16 hens per replicate. The experiment consisted of a 10-day pre-trial period, followed by a 56-days trial period. The results showed that hens receiving 0.30 mg/kg SY exhibited a significantly higher laying rate compared with the CON (P < 0.05), with the selenium content in eggs also increasing linearly with increasing amounts SY (P < 0.05). Similarly, dietary SY markedly enhanced antioxidant enzyme activities (GSH-Px, SOD) in the liver, serum, and ovary (and upregulated HO-1, NQO-1). as well as ovarian Bcl-2 mRNA (P < 0.05), while inhibiting caspase-3 and Bax expression (P < 0.05). Furthermore, 0.15 and 0.30 mg/kg SY significantly increased the plasma levels of FSH, E₂, LH and Prog (P < 0.05), along with upregulated expression of FSHR, and LHR in the ovary as well as Erα and Erβ in the liver (P < 0.05). SY supplementation also significantly enhanced the expression of genes involved in yolk precursor synthesis, including APOVLDLⅡ, VTGⅡ and Apo B (P < 0.05). Finally, hens receiving 0.30 mg/kg SY showed significantly higher levels of VTG, VLDLy and VLDLR in the liver, serum and ovary (P < 0.05). However, SY had no significant effects on cecal microbial diversity or dominant bacterial taxa (P > 0.05). In summary, dietary SY supplementation can improve laying performance in hens by enhancing reproductive hormone levels, boosting antioxidant capacity in hepatic and ovarian tissues and promoting yolk precursor synthesis.