Effects of dietary supplementation of synthetic antimicrobial peptide-A3 and P5 on growth performance, apparent total tract digestibility of nutrients, fecal and intestinal microflora and intestinal morphology in weanling pigs

The present study investigated the effects of dietary supplementation of synthetic antimicrobial peptide-A3 and P5 (AMP-A3 and P5) on growth performance, apparent total tract digestibility (ATTD) of nutrients, fecal and intestinal microflora, serum immunoglobulins and intestinal morphology of weanling pigs. Pigs (n=240; Landrace×Yorkshire×Duroc, initial body weight: 5.9±0.56 kg) were randomly allotted to four treatments on the basis of BW. There were four replicates in each treatment with 15 pigs per replicate. Dietary treatments were negative control (NC; basal diet without antimicrobial growth promoters), positive control (PC; basal diet+150 mg/kg diet avilamycin), basal diet with 60 mg/kg AMP-A3 (A3) and basal diet with 60 mg/kg AMP-P5 (P5). Diets were fed for 28 d. The overall ADG and G:F of pigs fed PC, A3 and P5 diets were greater (P<0.05) than pigs fed the NC diet. Also, the overall ADG of pigs fed the PC diet was greater (P<0.05) than pigs fed the A3 and P5 diets. The G:F of the pigs fed the PC diet was greater (P<0.05) than pigs fed the A3 diet, whereas, G:F of pigs fed the P5 diet was not different (P>0.05) from pigs fed the PC diet. Pigs fed the PC, A3 and P5 diets had greater (P<0.05) ATTD of GE, CP (phase I and II) and DM (phase II) than pigs fed the NC diet. Moreover, ATTD of CP (phase I and II) and GE (phase II) of pigs fed the PC diet was greater (P<0.05) than pigs fed the A3 and P5 diets. At d 28, pigs fed the PC, A3 and P5 diets had fewer (P<0.05) fecal Clostridium spp. and coliforms than pigs fed the NC diet. Moreover, pigs fed the PC and P5 diets had fewer (P<0.05) ileum and cecal total anaerobic bacteria, Clostridium spp. and coliforms than pigs fed the NC diet. Pigs fed the PC, A3 and P5 diets had greater (P<0.05) villus height and villus height:crypt depth (VH:CD) of duodenum and jejunum than pigs fed the NC diet. Dietary treatments had no effects (P>0.05) on apparent ileal amino acids digestibility and serum immunoglobulins (IgG, IgA, IgM) concentrations. These results indicate that AMP-A3 and P5 have potential to improve the growth performance, nutrient digestibility, intestinal morphology and to reduce pathogenic bacteria in weanling pigs. The impact on several of the measured response parameters was quantitatively low, though. Therefore, further studies are needed to confirm the current results.