Abstract
The objective of this study was to determine the bidirectional effects between hepatic gene expression and gut microbial communities on regulating the productive performances and egg quality of the layer hens in late-laying period after receiving fasting-induced molting treatment. A total of three hundred and sixty 380-day-old Jingfen No. 6 layer hens from the same batch were randomly divided into the control group (CON) and the fasting-induced molting group (FM), each group contained 9 replicates, with 20 chickens in each replicate. Productive performances and egg quality were meticulously recorded for each replicate, followed by the sampling of one bird from each replicate for the intestinal morphological analysis. The16S rRNA and transcriptomic sequencing methods were conducted for microbial communities and hepatic gene expressions investigation between CON and FM treatments to investigate the potential regulatory effects on productive performances and egg quality. Results showed that the egg production rate showed no significant difference between CON and FM groups before FM treatment, while effectively increased after FM treatment. Egg quality measurement results indicated the FM treatment significantly increased the albumen height and Haugh unit (P < 0.05), which showed no significant discrepancies between CON and FM in the pre-FM stage. Intestinal morphological results showed no significant differences on villus Height, crypt depth, and V/C ratio of jejunum and ileum in the pre-FM stage, while the villus height and crypt depth of the jejunum significantly decreased (P < 0.05) after receiving FM treatment. Bacterial community results showed that indexes of Shannon and sobs significantly increased after FM treatment(P < 0.05). Relative abundances of Alistipes.spp, Faecalicoccus.spp, Peptococcus.spp, Alloprevotella.spp, Sellimonas.spp, Lactobacillus.spp and Bifidobacterium.spp significantly increased (P < 0.05) after receiving FM treatment. Hepatic gene expression results showed that the differential expressed genes are mainly enriched in the Biosynthesis of unsaturated fatty acids, fatty acid elongation, steroid biosynthesis, and PPAR signaling pathways. Bidirectional results showed that hepatic genes and cecal bacterial communities synergistically interacted in modulating egg weight, albumen height, and Haugh unit. Conclusion: Hepatic genes and gut bacteria bilaterally cooperated and synergistically promoted the laying rate, albumen height, and Haugh unit of FM-treated layer hens through modulating the nutrient absorption and physiological lipid metabolism. Our findings may provide a theoretical basis for the fasting-induced molting process and further extend the laying cycles in the layer hens production.