Jun Zhang

Fasting‐induced molting (FIM) rejuvenates the laying cycle in hens; however, the fasting process may result in intestinal dysbiosis, which compromises host immunity and disrupts the intestine‐liver function. Consequently, investigating the changes in gut microbiota during FIM and its impacts on gut‐liver metabolic homeostasis is crucial for enhancing the efficiency of FIM in laying hens. Here, a total of 90 laying hens, aged 60 weeks, were selected for the FIM. Samples were collected at four time points: the day before fasting, the 15th day of fasting, the 5th day of refeeding, and the 47th day of refeeding. Metagenomic sequencing and non‐targeted metabolomics were employed to investigate the roles of the gut microbiota and metabolites in the remodeling of gut–liver function, focusing on intestinal injury‐repair mechanisms and changes in liver function. During the fasting period, the abundance of harmful microbiota and metabolites increase, leading to intestinal injury. This process activates the TGF‐beta signaling pathway, promoting intestinal stem cell proliferation. Simultaneously, liver function dysfunction as evidenced by elevated bile acid levels in the liver and serum and activation of the non‐classical bile acid synthesis pathway. During the refeeding period, the previously observed effects were reversed, leading to the remodeling of the intestinal microbiota and gut‐liver function. We identified key microorganisms ( Liquorilactobacillus mali and Tissierellia bacterium KA00581) and functional metabolites ( d ‐Panthenol and 3‐hydroxyanthranilic acid (3‐HAA)) involved in intestinal‐liver function during FIM. Notably, d ‐Panthenol promotes chicken small intestinal organoid branching and growth, enhances barrier function, and reduces inflammation. Our study underscores the role of gut microbiota in gut‐liver injury during FIM in laying hens, suggesting potential probiotic‐ or metabolite‐based interventions to mitigate gut‐liver injury and facilitate recovery.

This study explored fasting‐induced physiological remodeling effects on meat quality in aged laying hens. Fasting for 15 days (F15) significantly reduced abdominal fat, intermuscular fat width, subcutaneous fat thickness, and liver index versus pre‐fasting (F0) ( p < 0.05), which recovered post‐refeeding. Breast/leg muscle quality was poorest at F15 but optimized by day 20 of refeeding (R20). Serum total cholesterol/triglycerides decreased during fasting ( p < 0.05), whereas low‐density lipoprotein rose, both normalizing post‐refeeding. Lipidomics identified 155 lipids (73.5% glycerophospholipids, mainly PC/PE) in pectoralis muscle; transcriptomics revealed 330 differentially expressed genes. Enriched pathways included glycerolipid/fatty acid metabolism. ACSL4 correlated with PC (14:0e/22:6), PC (14:0/20:4), and PC (14:0/18:2) (|R| > 0.7). Fasting upregulated ACSL4/LPCAT, enhancing acyl‐CoA and lipid reacylation to drive phospholipid remodeling, improving meat quality.

Fasting-induced molting (FIM) is a common method used to improve the laying performance of aged laying hens. Nevertheless, this approach may impose various stresses on chickens, such as disruptions in intestinal flora and inflammation issues within the intestines. However, the impact of an imbalance in intestinal flora on intestinal health during the FIM process remains elusive. Therefore, intestinal injury, the microbiome, and the metabolome were analyzed individually and integrated to elucidate the impact of the intestinal flora on intestinal health during the FIM process. The findings indicated that fasting resulted in a notable reduction in villus height and villus/crypt ratio, coupled with elevated levels of intestinal inflammation and permeability. During the fasting period, microbiota compositions changed. The abundance of Escherichia_Shigella increased, while the abundance of Ruminococcaceae_UCG-013 and Lactobacillus decreased. Escherichia_Shigella was positively correlated with Citrinin and Sterobilin, which lead to intestinal inflammation. Ruminococcaceae_UCG-013 and Lactobacillus exhibited positive correlations with Lanthionine and reduced Glutathione, thereby reducing intestinal inflammation. This study screened the intestinal probiotics, Ruminococcaceae UCG-013 and Lactobacillus, that influence gut health during the fasting period, providing an experimental basis for improving gut microbiota and reducing intestinal inflammation during the FIM process.