Dietary fishmeal replacement with a mixed‐blend protein evokes sex‐specific differences on culture performance and physiological effects on Chinese mitten crab

The aim of this study was to assess the effects of fishmeal replacement using a mixed blend of fermented soybean, chicken, blood, pork and shrimp meal in the diets for subadult Chinese mitten crab (Eriocheir sinensis). Five diets were formulated by replacing 0%, 17%, 33%, 50% and 67% of fishmeal with a protein mixture (Diet 1–Diet 5). The subadult crabs (male: female = 1:1) were stocked into 15 ponds in triplicate and fed the experimental diets for 110 days. The results showed that there was no significant difference in the survival and growth of crabs in all treatments. The hepatosomatic index and total lipid content of males increased, while the crude protein content decreased with fishmeal replacement. However, the gonadosomatic index, meat yield, total edible yield and their respective nutritional compositions were minimally affected in both males and females. The serum glutamic–pyruvic transaminase activity of male and female crabs fed Diet 5 was significantly highest, while the hepatopancreas MDA content of males fed Diet 4 was highest. An economic analysis demonstrated that the highest production value and partial gross returns were apparent when feeding Diet 4. This study suggests the optimal level of fishmeal replacement was 33% and 50% for male and female crabs, respectively.