The effects of different antimicrobial peptides on the cecal metabolome of laying hens

Against the backdrop of the global comprehensive ban on antibiotics, finding antibiotic alternatives to address the intestinal health issues of laying hens during the late laying phase has become an urgent priority. In this study, antimicrobial peptides (AMPs) were used as additives, and a metabolomic approach was employed to investigate the effects of AMPs targeting Gram-positive bacteria (AMP1), AMPs targeting Gram-negative bacteria (AMP2), and their complex (AMP3), on the intestinal metabolome of Xinyang Black-feathered laying hens in the late laying phase. First, we found through in vitro experiments that the selected AMPs exhibited significant antibacterial effects. Subsequently, these AMPs were added to the feed for in vivo validation in laying hens, and differential metabolites were screened using a threshold of corrected P-value ≤ 0.05. The results showed that AMPs targeting Gram-negative bacteria exerted favorable effects on the cecal intestinal microbiota of Xinyang Black-feathered laying hens in the late laying phase. Compared with the CG, the AMP1, AMP2, and AMP3 groups had 79, 433, and 64 differential metabolites, respectively. The AMP1 and AMP2 groups were significantly enriched in metabolic pathways such as glycine, serine, and threonine metabolism, and aminoacyl-tRNA biosynthesis. The AMP2 group was significantly enriched in the nucleotide metabolism and linoleic acid metabolism pathways. Metabolites in these pathways may be involved in the host's antioxidant capacity and immune regulation processes when responding to antimicrobial substances. It is concluded that AMPs targeting Gram-negative bacteria exert a favorable effect on the intestinal microbiota of Xinyang Black-feathered Laying Hens in the late laying phase. This study holds significant importance for safeguarding the health of laying hens and stabilizing their production performance, and provides new insights for the subsequent development of the layer poultry industry.