Unraveling the regulatory mechanisms of fasting-induced molting on follicle development in laying hens.

Fasting-Induced Molting (FIM) has been shown to enhance the laying rate and extend the laying cycle of hens in the late laying period. However, the precise regulatory mechanism underlying FIM's effects on follicle development remains unknown. This study aimed to elucidate these mechanisms by utilizing RNA-seq to analyze the gene expression changes during FIM and identify the key genes involved in follicle development, thereby uncovering the molecular pathways through which FIM exerts its regulatory effects. A total of 96 Houdan hens, aged 326 days, were selected for FIM treatment. The results indicated a progressive increase in the number of small white follicles, as well as primary and secondary follicles, during the fasting and recovery phases. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and anti-Müllerian hormone (AMH) were reduced during the fasting period but gradually rebounded during refeeding. RNA sequencing and real-time quantitative PCR (qRT-PCR) analyses identified the PI3K-AKT signaling pathway as a crucial regulator of ovarian remodeling. Protein-Protein Interaction (PPI) analysis revealed that genes from the collagen family, particularly COL1A1, exhibit strong connectivity. In vitro experiments on cultured ovaries treated with varying concentrations of COL1A1 revealed that COL1A1 promotes ovarian cell proliferation, activates the PI3K-AKT signaling pathway, and upregulates the expression of GDF9 and BMP4. Masson staining results revealed significant collagen deposition in the ovary at the onset of FIM (F0), which was markedly reduced at F15. Collagen deposition re-emerged during the later stages of refeeding. In conclusion, this study identified the key genes regulating follicle development during the FIM and demonstrated that FIM can alleviate ovarian collagen deposition. These findings elucidate the molecular mechanism underlying FIM's regulatory effects on follicle development, providing a theoretical foundation for enhancing ovarian function in laying hens and optimizing FIM protocols.