Effects of dietary Chaihu-Shugan-San on egg production performance, egg quality, and hepatic lipid metabolism of late-laying hens.

This study aimed to evaluate the effects of Chaihu-Shugan-San (CSS) on egg production, egg quality, ovarian development, serum lipid levels, liver function, and hepatic lipid metabolism in laying hens. A total of 480 67-week-old laying hens (Jinghong No. 1) were randomly assigned to four groups. Each group comprised eight replicates of 15 hens. A basal diet was fed to the control group (CON), and a basal diet supplemented with 0.5% (CSS1), 1.5% (CSS2), or 2.5% CSS (CSS3) was fed to the other groups, respectively. The trial lasted 8 weeks. The results showed a significant increase in the egg-laying rate of the CSS2 group by 6.80% than the CON group (p < 0.05). Haugh unit was 9.34%, 10.45%, and 7.97% higher in the CSS1, CSS2, and CSS3 groups than in the CON group (p < 0.05). Eggshell thickness of the CSS2 group was found to be 38.68% greater than the CON group (p < 0.05). The oviduct index was enhanced by 31.53%, 19.70%, and 26.89% in the CSS1, CSS2, and CSS3, respectively (p < 0.05). The hens in the CSS2 and CSS3 groups displayed a greater number of SYF, at 71.73% and 52.43% (p < 0.05). The serum triglyceride (TG) levels demonstrated a significant increase in the CSS2 group, with 40.15% (p < 0.05). The identification of 1,826 and 1,828 lipid compounds in the CON and CSS groups, respectively, was indicated by lipidomics analysis. 175 differential lipids (SDLs) were upregulated and 60 SDLs were downregulated significantly. Kyoto Encyclopedia of Genes and Genomes (KEGG) topological analysis indicated that SDLs in the liver were primarily enriched in the metabolism of glycerophospholipid, glycerolipid, and glycine, serine, and threonine. In conclusion, dietary CSS supplementation improves egg-laying rate and egg quality during the late-laying period, while reducing liver fat accumulation. Dietary level of 1.5% is recommend. The reason may be due to its effects on hepatic lipid profile and metabolism, especially through glycerophospholipid and glyceride metabolism pathways.