Effects of Antimicrobial Peptides on the Growth Performance of Squabs Were Investigated Based on Microbiomics and Non-Targeted Metabolomics

This study aims to investigate the effects of dietary supplementation with AMPs on the growth performance, antioxidant capacity, and intestinal health of squabs. Furthermore, metagenomic and metabolomic approaches were employed to identify key differential bacterial species and metabolites associated with growth performance, and thereby the potential mechanisms underlying the enhancement of squab growth and development by AMPs being elucidated. One hundred and twenty pairs of healthy adult White Carneau pigeons (2 years old) were randomly divided into two groups, the control group (CK, fed with basal diet) and antimicrobial peptide group (AP, fed with basal diet +200 mg/kg antimicrobial peptide), with 10 replicates per group and 6 pairs of breeding pigeons per replicate. The experiment lasted for 53 days, including 7 days of prefeeding, 18 days of incubation and 28 days of feeding. In this study, squabs were weighed at 0 and 28 days of age to evaluate growth performance. At 28 days of age, duodenal contents were collected to assess digestive enzyme activities, while jejunal and liver tissues were harvested to determine antioxidant capacity. Intestinal morphology was examined using tissue samples from the duodenum, jejunum, and ileum. Finally, ileal contents were collected for a comprehensive analysis of microbial composition and metabolite profiles in the two experimental groups, employing high-throughput sequencing and LC-MS/MS techniques. The results showed that body weight, liver total antioxidant capacity (T-AOC), jejunal malondialdehyde (MDA) content, jejunum and ileum villus height-to-crypt depth ratio (VH/CD) were significantly increased, and jejunal crypt depth (CD) was significantly decreased in the AP group at 28 days of age (<i>p</i> < 0.05). In addition, the microbiome data showed that <i>Lactobacillus</i> in the AP group was a biomarker with significant differences (<i>p</i> < 0.05). Metabolomics analysis showed that the steroid hormone biosynthesis pathway was significantly different between the two groups (<i>p</i> < 0.01). In addition, the content of potentially beneficial metabolites (Biotin, beta-Tocotrienol, 7-Chloro-L-tryptophan and Dihydrozeatin) was significantly increased in the AP group (<i>p</i> < 0.05). These results indicate that dietary AMPs can significantly improve the body weights, liver antioxidant capacity and jejunum and ileum VH/CD of squabs.