THREE DIFFERENT DIETS ON THE GROWTH, DIGESTIVE ENZYME ACTIVITY, NUTRITION AND QUALITY OF CHINESE MITTEN CRAB (ERIOCHEIR SINENSIS)

This experiment aims to investigate the effects of feeding three diets types on the growth, digestive enzyme activity, nutrition and quality of Chinese mitten crab (Eriocheir sinensis). The experiment was divided into three groups: iced fish group (fed with iced fish after June), formula feed group (fed with formula feed after June), and black soldier fly larvae group (fed with black soldier fly larvae after June). Each group has 4 replicates, with 4 replicates per group. During the 90 days aquaculture period from August to October, samples were taken on the 20th of each month for relevant experimental analysis. The results showed that there was no significant difference in body weight, gonadal index (GSI), and total edible yield (TEY) among the three groups of Chinese mitten crab in October (P>0.05). The hepatosomatic index (HSI) of the black soldier fly larvae group was the highest. In terms of digestive enzyme activity in the hepatopancreas, there was no significant difference in amylase (AMS) and trypsin (TRY) activity among the three groups (P>0.05), while lipase (LPS) activity was the highest in black soldier fly larvae group. Among the fatty acids in hepatopancreas, the black soldier fly larvae group had the highest content of total saturated fatty acids (∑SFA), while the iced fish group had the highest content of monounsaturated fatty acids (∑PUFA) and polyunsaturated fatty acids (∑MUFA); Among the gonadal fatty acids, the formula feed group had the highest content of ∑SFA, ∑PUFA, and ∑MUFA; Among muscle fatty acids, the black soldier fly larvae group had the highest levels of ∑SFA, ∑PUFA, and ∑MUFA. The essential amino acids (EAA), nonessential amino acids (NEAA), and total amino acid content (TEAA) were all the highest in the black soldier fly larvae group (P>0.05). There was no significant difference in amino acids in hepatopancreas among the three groups. There was a significant difference (P<0.05) among the three groups in muscle amino acids, with the highest content in iced fish group and the lowest content in formula feed group; EAA, NEAA, and TEAA were all the highest in the formula feed group (P>0.05). Research has shown that three feed types have no significant effect on the growth of Chinese mitten crab, while formula feed can increase the content of fatty acids in gonads, while black soldier fly larvae group can increase the content of amino acids in hepatopancreas, indicating that formula feed is more conducive to the green development of Chinese mitten crab.