Dietary supplemented antimicrobial peptide microcin J25 improves the growth performance, apparent total tract digestibility, fecal microbiota, and intestinal barrier function of weaned pigs

Microcin J25 (MccJ25) is an antimicrobial peptide produced by a fecal strain of Escherichia coli containing 21 AA. This study was performed primarily to evaluate the effects of MccJ25 as a potential substitute for antibiotics (AB) on growth performance, nutrient digestibility, fecal microbiota, and intestinal barrier function in weaned pigs. In the present study, 180 weaned pigs (7.98 +/- 0.29 kg initial BW) were randomly assigned to 1 of 5 treatments, including a basal diet (CON) and CON supplemented with AB (20 mg/kg colistin sulfate; ABD) or 0.5, 1.0, and 2.0 mg/kg MccJ25. On d 0 to 14, dietary supplementation with MccJ25 and ABD had positive effects on ADG, ADFI, diarrhea incidence, and G: F (P < 0.05). Pigs fed the 2.0 mg/kg MccJ25 diet had greater ADG (P < 0.05) and marginally greater G: F (P < 0.10) compared with pigs fed the ABD diet. Compared with the CON diet, the 2.0 mg/kg MccJ25 diet sharply improved (P < 0.05) ADG and G: F and decreased (P < 0.05) diarrhea incidence (d 15 to 28 and d 0 to 28). Apparent digestibility of nutrients in pigs fed 1.0 and 2.0 mg/kg MccJ25 was improved (P < 0.05) compared with that of pigs fed CON and ABD. The serum cytokines IL-6 and IL-1 beta and tumor necrosis factor-alpha levels in pigs fed MccJ25 were greater than in pigs fed CON (P < 0.05). Additionally, the IL-10 concentration in pigs fed MccJ25 was sharply increased (P < 0.05) compared with that of pigs fed CON. Pigs fed 1.0 and 2.0 mg/kg MccJ25 diets had remarkably decreased d-lactate, diamine oxidase, and endotoxin concentrations and fecal E. coli numbers (P < 0.05) and improved fecal Lactobacillus and Bifidobacterium numbers (P < 0.05). Compared with the ABD diet, the diet containing 2.0 mg/kg MccJ25 did not increase d-lactate, diamine oxidase, and endotoxin (d 14) concentrations (P < 0.05) or decrease the Lactobacillus and Bifidobacterium (d 28) numbers (P < 0.05). The diets containing 1.0 and 2.0 mg/kg MccJ25 and ABD (d 28) improved lactate concentration and short-chain fatty acid concentrations, including acetate, propionate, and butyrate, in feces (P < 0.05). Moreover, the pigs fed 2.0 mg/kg MccJ25 had greater lactate, butyrate (d 14), and propionate concentrations than the pigs fed the ABD diet (P < 0.05). In conclusion, dietary supplemented MccJ25 effectively improved performance, attenuated diarrhea and systematic inflammation, enhanced intestinal barrier function, and improved fecal microbiota composition of weaned pigs. Therefore, MccJ25 could be a potential effective alternative to AB for weaned pigs.