Abstract
The declines in laying performance during the late production period have adverse effects on the length of the production cycle. Improving the nutrition of laying hens is a crucial measure to reverse this declination. This study investigated the effect of selenium yeast (SY) on egg production, ileal gene expression and microbiota, as well as elucidating their associations in aged laying hens. A total of 375 Jinghong laying hens at 76 weeks old were randomly assigned into 5 dietary treatments, which included a selenium-deficient basal diet based on corn-soybean meal, and dietary supplementation of SY at 0.15, 0.30 and 0.45 mg/kg, and sodium selenite at 0.45 mg/kg. The results showed that SY ameliorated the depression in aged laying performance in the 0.30 mg/kg group (P < 0.01). Selenium yeast significantly increased ileum selenium concentration (P < 0.05), and SY groups had higher selenium deposition efficiency than the sodium selenite group. Functional enrichment and Short Time-series Expression Miner (STEM) analysis indicated that SY activated metabolic progress (e.g., glycerolipid metabolism, glycerophospholipid metabolism, and fatty acid metabolism), immune response and oxidative stress response. Four hub genes including thioredoxin reductase 1 (TXNRD1), dihydrolipoamide dehydrogenase (DLD), integrin linked kinase (ILK) and leucine zipper tumor suppressor 2 (LZTS2) were involved in intestinal metabolism which was closely associated with selenium deposition/status. Moreover, the relative abundance of Veillonella, Turicibacter and Lactobacillus was significantly increased, but the relative abundance of Stenotrophomonas was significantly decreased by SY supplementation. Multi-omics data integration and Canonical correspondence analysis (CCA) showed that both the ileum selenium content and the laying rate were highly correlated with pathways and bacteria enriched in metabolism and immune response. Meanwhile, the "switched on" gene prostate stem cell antigen (PSCA) had a positive relationship with Veillonella and a negative relationship with the opportunistic pathogens Stenotrophomonas. Overall, our study offered insight for the further exploration of the role of SY on boosting egg production and balancing ileum intestinal flora in aged laying hens.