Effects of antimicrobial peptides in nursery diets on growth performance of pigs reared on five different farms

The objective of the present experiment was to evaluate the effects of dietary supplementation with antimicrobial peptides (AMPs) on growth performance, diarrhea incidence, and survival rate of weaned pigs reared at 5 commercial farms (Farms A-E). Pigs (Farm A, n=486, genotype=Yorkshire (Y)×Landrace (L), weaning age=28±3 d; Farm B, n=360, genotype=Y×L×Duroc (D), weaning age=30±2 d; Farm C, n=558, genotype=Y×L×D, weaning age=30±2 d; Farm D, n=828, genotype=Y×L×D, weaning age=32±3 d; Farm E, n=576, genotype=Y, weaning age=24±3 d) were blocked (within farm) by body weight (BW) and sex and randomly assigned to 1 of 3 treatments: (1) a basal diet (control); (2) 2.0 g/kg of AMPs (AMPs-2) and (3) 3.0 g/kg of AMPs (AMPs-3). The AMPs used in the present study were a mixture of lactoferrin, cecropin, defensin, and plectasin. Each treatment group consisted of 6 replicates per farm. Each replicate consisted of 2 pens of 13-14 pigs, 2 pens of 10 pigs, 3 pens of 10-11 pigs, 4 pens of 11-12 pigs and 3 pens of 10-11 pigs on Farms A, B, C, D, and E respectively. Dietary supplementation with AMPs enhanced (linear, P<0.05; quadratic, P<0.05) average daily gain (ADG) of weaned pigs on all 5 farms. The average daily feed intake (ADFI) was increased (quadratic, P<0.05) by dietary supplementation with AMPs. The feed conversion rate (G:F) was also enhanced (linear, P<0.05) when AMPs were included in the diets of weaned pigs on commercial farms. The diarrhea incidence of AMPs-supplemented pigs was less (P<0.001) than that in control pigs. The survival rate of pigs fed AMPs-supplemented diet was higher (P<0.01) than that of control pigs. The present results indicated that AMPs had beneficial effects on growth performance, reduced the incidence of diarrhea, and increased the survival rate of weaned pigs.