Effects of replacement of fish meal with housefly maggot meal on digestive enzymes, transaminases activities and hepatopancreas histological structure of Litopenaeus vannamei

To investigate the effects of housefly maggot meal (HMM) on the digestive enzymes, transaminases activities and hepatopancreas histological structure of Litopenaeus vannamei, we formulated 5 diets with 20%, 40%, 60%, 80% and 100% replacement of fish meal with HMM in basal diet, and fed them to L.vannamei (initial weight 0.56 g) for 45 d. Results show that no significant difference was found in digestive enzymes activities in hepatopancreas, stomach and intestine of L.vannamei in HMM groups compared to the control (P＞0.05). The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in hepatopancreas inHMM groups were lower than those in the control with no significant difference (P＞0.05), while serum ALT activity in 100% group and AST activities in 60%~100% groups decreased significantly (P0.05). Compared to the control, numbers of vacuoles increased and unknown substances appeared in the epithelial cells in 20%~60% groups; hepatopancreas histological structures were seriously injured in 80% and 100% groups. In conclusion, when the substitution level is lower than 60%, HMM has neither significant effects on digestive enzymes and transaminases activities of L.vannamei nor serious injury to hepatopancreas histological structure.