Effects of induced molting on lipid accumulation in liver of aged laying hens

As the age of laying increases, the metabolic capacity of the liver decreases, leading to excessive lipid accumulation, which seriously affects the laying performance of laying hens. Induced molting (IM) can rejuvenate the reproductive system of older laying hens, allowing them to enter a new laying cycle. However, it remains unclear whether induced molting can enhance lipid accumulation in the liver of aged laying hens and what the underlying mechanism might be. In this study, fasting-induced molting was performed on 70-week-old Hy-line brown laying hens, and the resulting metabolic changes were analyzed using non-targeted metabolomics. Serum lipid levels, liver oxidative stress, and inflammation were measured using kits, while autophagy and lipid metabolism-related factors were assessed through immunofluorescence and western blotting. The results showed that IM could promote hepatic lipid deposition in aged laying hens, reduce hepatic steatosis and injury, lower the blood lipid level, improve hepatic antioxidant capacity and increase egg production rate. During the fasting period, the hepatic autophagic system was activated in laying hens and the level of hepatic autophagy increased. Additionally, AMPK phosphorylation levels increased, while the expression of fatty acid synthesis genes SREBP-1C, ACC, and FASN decreased (P < 0.01). The expression of PPARα, PGC 1α and CPT1A, which are associated with fatty acid oxidation, was upregulated (P < 0.01). In conclusion, IM enhanced lipid metabolism, increased liver autophagy, and improved liver function in aged laying hens.