Effects of Curcumin on the Egg Quality and Hepatic Lipid Metabolism of Laying Hens

Simple Summary The poultry industry is increasingly seeking natural, safe, and cost-effective feed additives, due to the ban on antibiotics and rising production demands. Curcumin, a natural plant extract, has demonstrated antioxidant and anti-inflammatory properties in feed additive studies. However, the mechanism by which curcumin supplementation improves the performance and health status of laying hens needs to be more thoroughly investigated. In this study, our results showed that a 200 mg/kg curcumin supplementation significantly enhanced egg quality by targeting and regulating oviduct expansion glycoprotein gene expression. Additionally, curcumin improved hepatic lipid metabolism in laying hens by regulating hepatic fatty acid synthesis genes. These findings provide a basis for considering curcumin as a valuable feed additive in the laying hen industry.Abstract Curcumin, the major active compound of turmeric, has shown potential benefits for poultry health and production in various studies. However, its specific role in enhancing the egg quality and liver health of laying hens, as well as its underlying mechanisms, have yet to be determined. Here, a total of 600 Su Qin No.1 Laying hens, aged 55 weeks and with similar laying rates, were randomly placed into five groups, with 10 replicates of 12 hens each. Curcumin doses of 0, 100, 200, 400, and 800 mg/kg were added to the basal diet to form the experimental groups. After an 8-week feeding period, no significant changes were observed in the production performance of laying hens due to curcumin supplementation. However, additional tests revealed that a 200 mg/kg curcumin supplementation improved albumen height, yolk color, Haugh unit, and eggshell thickness, while reducing the thin albumen's weight and proportion. This was accompanied by a significant down-regulation of the mRNA expression level of the Prolactin Receptor (Prlr) in the oviduct magnum. Furthermore, the number of hepatic lipid droplets and the hepatic triglyceride (TG) content, as well as malondialdehyde (MDA) levels were significantly reduced, indicating improved hepatic lipid metabolism and oxidative status. This was accompanied by a significant reduction in the expressions of sterol regulatory element binding protein-1 gene (Srebp-1), fatty acid synthase gene (Fasn), as well as fatty acid synthase (FASN), which are closely related to fatty acid synthesis in the liver. Overall, these findings suggest that curcumin supplementation at a dosage of 200 mg/kg could lead to significant improvements in egg quality and hepatic lipid metabolism.