Effects of antibacterial peptide microcin J25 on growth performance, antioxidant capacity, intestinal barrier function and intestinal microbiota in pigeon squabs

The present study aims to evaluate the effects of the antibacterial peptide Microcin J25 (ABP MccJ25) on growth performance, intestinal barrier function, antioxidant capacity and ileal microbiota in pigeon squabs. The 80 pairs of American Silver King pigeon parents and 240 healthy day 1 squabs were randomly divided into four groups, including 4 parent pairs and 12 pigeon squabs per group with 5 replicates. Parent pigeons were fed a basal diet (CON) or the addition of 100, 200, 300 mg/kg of ABP MccJ25 (ABP100, ABP200, and ABP300, respectively) for 4 weeks. Results showed that the group ABP200 remarkably reduced the feed conversion ratio and increased average daily gain in pigeon squabs from 7 to 21 d (p < 0.05), and improved serum antioxidant capacity in pigeon squabs from 14 to 28 d (p < 0.05). Villus height and the ratio of villus height to crypt depth in the duodenum, jejunum, and ileum were significantly increased in groups ABP200 and ABP300 (p < 0.05). In addition, group ABP200 obviously up-regulated the relative mRNA expression of intestinal antioxidant-related genes and barrier-related genes (p < 0.05). Moreover, the proportion of beneficial bacteria including Firmicutes and Lactobacillales, which were favourable to the intestinal health of pigeon squabs increased noticeably (p < 0.05). Taken together, these results indicated that group ABP200 enhanced antioxidant capacity, strengthened intestinal barrier function, and facilitated the regulation of intestinal microbiota, leading to the improvement in growth performance of pigeon squabs. Therefore, this study provides support for the application of 200 mg/kg ABP MccJ25 in pigeon production.