Effects of formula feed and frozen fish on the growth, gonadal development and muscle quality of Eriocheir sinensis in the monomer culture

Eriocheir sinensis is one of the most widely commercially cultured crabs which is generally cultured in the ponds mainly fed with formula feed, frozen fish and mixture with formula feed and frozen fish. However, high-density pond culture and feeding frozen fish with unstable source and imbalanced nutrition bring many problems such as severe diseases outbreaks and variable quality of crabs, water pollution and so on. Therefore, to study the effect of formula feed and frozen fish on the breeding performance and nutritional status of the crabs, this experiment analyzed the growth performance, gonadal development and nutrient composition of monocultured crabs by continuous sampling, and further compared the final body weight (FBW), weight gain rate (WGR), specific growth (SGR), survival rate (SR) and molting intervals (MI). The results showed that: ① In terms of SR, the formula feed group was significantly higher than those of the frozen fish group, while there was no significant difference in the FBW, WGR, SGR and MI between the two groups. At different molting stages, the boby weight of the formula feed group was smaller than the frozen fish group, and the differences between the two groups after the third molting was significant; the WGR was different between the female and male crabs, and the WGR of formula feed group in the female crab was significantly smaller than that of the frozen fish group after the second molting, while the male crabs in the two stages after the first and fourth molting were significantly larger than those of the frozen fish group. ② The hepatopancreas indices (HSI) were 3.59% and 4.45% in the formula feed and frozen fish groups, respectively, while the gonadosomatic indices (GSI) were 3.20% and 2.25%, respectively; and the HSI and GSI had no significant differences in the two groups. ③ In terms of muscle amino acid content, the total amino acids (∑TAA), total essential amino acids (∑TEAA) and total flavor amino acids (∑FAA) in the formula feed group were significantly smaller than those of the frozen fish group; From the perspective of a single amino acid, the lysine and arginine contents of the formula feed group were significantly smaller than those of the frozen fish group, while the content of proline was significantly greater in formula feed than that in the frozen fish group. ④ In terms of muscle fatty acid content, the highly unsaturated fatty acids (∑HUFA) and DHA+EPA contents of the formula feed group were significantly higher than those of the frozen fish group; In addition, the contents of C16:1 and C18:1n-9 in the monounsaturated fatty acid (∑MUFA) were significantly smaller in the formula feed group than those of the frozen fish group, but in the polyunsaturated fatty acids (∑PUFA), the contents of ARA and DHA of formula feed group were significantly higher than those of the frozen fish group. This study has shown that the formula feed group is close to the frozen fish group in the growth performance and muscle quality of the Chinese mitten crab, but the gonadal development and SR of the crabs fed with formula feed are better than the frozen fish group under the monomer culture conditions. So formula feed has more development advantages in aquaculture.