Effects of recombinant antimicrobial peptides on growth and immu-nity in tilapia (GIFT)

Abstract

Antimicrobial peptides have attracted considerable attention because of their potential use for therapy and prophylaxis.We evaluated the effects of dietary supplementation with recombinant antimicrobial peptide on growth,immunity,and performance in the protest test in tilapia(genetically improved farmed tilapia,GIFT)(ini-tial body weight 10.68 g±0.53 g).The fish were divided into six treatment groups and fed experimental diets con-taining 0,5,10,20,or 50 mg/kg recombinant antimicrobial peptide(RAP) derived from Fenneropenaeus chinensis or 100 mg/kg florfenicol for 56 d.Weight gain,red blood cell numbers,and catalase activity were significantly higher in the groups supplemented with 5 and 10 mg/kg compared with the control.The specific growth rate was highest in the group given 5 mg/kg RAP.Liver superoxide dismutase activity and serum lysozyme activity were significantly lower in the group given 50 mg/kg RAP than in the control.Supplementation with 100 mg/kg flor-fenicol increased the number of red blood cells,but had no effect on the other indexes.Following infection with Aeromonas hydrophila,the death rate was significantly lower in groups fed between 5–20 mg/kg RAP than in the control.The survival was highest in the group fed 5 mg/kg.Our results suggest that dietary supplementation with appropriate levels of antimicrobial peptide improves growth,immunity,and performance in the protest test in tila-pia.However,increasing the dose can lead to negative effects on growth and enzyme activity.Therefore,we rec-ommend that supplementation should not exceed 20 mg/kg.Our results provide insight into the proper application of recombinant antimicrobial peptides to tilapia.