Influence of replacing fish meal with enzymatic hydrolysates of defatted silkworm pupa (Bombyx mori L.) on growth performance, body composition and non-specific immunity of juvenile mirror carp (Cyprinus carpio var. specularis)

This study was conducted to investigate the effects of dietary supplementation of enzymatic hydrolysates of defatted silkworm pupa (EHDSP) on growth performance, body composition and non-specific immunity of juvenile mirror carp (Cyprinus carpio var. specularis). The control diet (EHDSP0) was produced using fish meal (FM) as the main protein source and the other four diets were formulated by substitution of 25% (EHDSP25), 50% (EHDSP50), 75% (EHDSP75) and 100% (EHDSP100) FM with EHDSP. Five groups containing 270 juvenile mirror carp (14.51 +/- 0.03 g) were fed to apparent satiation for 8 weeks. The results indicated that the special growth rate, weight gain, protein efficiency ratio and feed conversion rate of experimental fish in EHDSP25 and EHDSP50 groups were not significantly different from EHDSP0 group (p > .05). The spleen index of experimental fish in EHDSP25 group was significantly higher than that of EHDSP0 group (p < .05). The muscle protein content of experimental fish in EHDSP25 and EHDSP50 groups was significantly higher than that of EHDSP0 group (p < .05). Serum alanine aminotransferase and total cholesterol of experimental fish fed with the EHDSP were significantly lower than that of control (p < .05). The activity of serum superoxide dismutase of experimental fish in EHDSP25, EHDSP50 groups was significantly higher than that of EHDSP0 group (p < .05). Intestinal trypsin activity of EHDSP25 group was significantly higher than that of EHDSP0 (p < .05). In conclusion, EHDSP can be included into diet to replace 50% FM of juvenile mirror carp without negative effect on growth, furthermore, it can improve the non-specific immunity and function of intestinal tract.