An investigation on the optimal lipid level for juvenile Chinese mitten crab ( Eriocheir sinensis ) reared under three salinities: Survival, growth, digestive enzyme activities, antioxidant capacity and body composition

Abstract

A 56‐day feeding experiment was performed to investigate the effects of the dietary lipid level on the survival, growth performance, digestive enzyme activities and antioxidant capacity of Eriocheir sinensis reared under three salinities. Six feeds with graded levels of lipids (5%, 7%, 9%, 11%, 13% and 15%) were formulated by including fish oil as the main lipid source. Sixty crab individuals (initial weight: 0.21 ± 0.02 g) were assigned to each aquarium. In total, 18 aquariums were distributed under each salinity condition. Each feed was randomly allocated to three parallel tanks of crabs. The feeding experiment lasted for 56 days. Results showed that the survival rate of E. sinensis fed diets with 7%–15% lipids just showed a decreasing tendency as the salinity increased. The highest weight gain rate (WGR) was found in the treatment with 11%, 9% and 5% lipid at the salinity of 0.5‰, 2‰ and 6‰ respectively. At the salinity of 0.5‰, 2‰ and 6‰, the highest activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) were detected in the treatments with 11%, 13% and 7% lipid respectively. As the salinity increased, the protein and lipid contents showed an increasing trend, while the moisture content showed an opposite trend. At each salinity, arachidonic acid and docosahexaenoic acid increased, while saturated fatty acids and monounsaturated fatty acids decreased with the increase of dietary lipid level. These results indicated that increasing salinity resulted in decreased antioxidant enzyme activities and increased malondialdehyde content in the juvenile E. sinensis, especially when they were fed diets with relatively higher lipid level. Based on WGR, digestive enzyme activity and antioxidant capacity, the optimal lipid level was estimated to be 8.28–13%, 7.54–13% and 5–8.89% for juvenile E. sinensis reared at the salinity of 0.5‰, 2‰ and 6‰ respectively.

Effects of prior acclimation on the survival, feed intake and salinity preference of a freshwater-adapted euryhaline crab

“…A previous study reported that, when exposed to 0 , 8 , 16 and 32 , early juvenile Chinese mitten crabs (Stage III) have the highest survival rate and the strongest physiological adaptability at 8 salinity (Yang et al, 2022). In addition, Wen et al (2022) found that the survival rate of juvenile Chinese mitten crabs was not significantly different under three salinities (0.5 , 2 and 6 ). They also found that the 6 salinity would not affect the body composition of juveniles and was harmless to the physiological condition of crabs with optimal feed lipid level (Wen et al, 2022).…”

“…In addition, Wen et al (2022) found that the survival rate of juvenile Chinese mitten crabs was not significantly different under three salinities (0.5 , 2 and 6 ). They also found that the 6 salinity would not affect the body composition of juveniles and was harmless to the physiological condition of crabs with optimal feed lipid level (Wen et al, 2022). Therefore, it is reasonable that low salinities (below 6 ) are survivable for juveniles in the intertidal habitat, even if the juvenile Chinese mitten crabs are considered to live in fresh water because of the peculiar character of their life cycle.…”

Study on the Optimal Phospholipid Addition Levels for Button-Sized Juvenile Chinese Mitten Crab (Eriocheir sinensis): Survival, Growth, Physiological Parameters, and Neverland Expression

“…This suggests that an adequate amount of lipids can be absorbed from the intestine and utilized for energy supply, leading to a decreased reliance on carbohydrates such as starch and cellulose [50]. Wen et al [51] have also demonstrated that a high ratio of carbohydrate to lipid is not conducive to the growth of juvenile E. sinensis. Furthermore, PL can increase the transportation of energy-supplying lipids, such as TG, to muscle or enhance the transfer efficiency of lipids into mitochondria for oxidation.…”