Dietary cholesterol level affects growth, molting performance and ecdysteroid signal transduction in Procambarus clarkii

The effects of dietary cholesterol supplementation on growth, molting performance and ecdysteroid signal transduction of juvenile crayfish Procambarus clarkii (initial weight = 3.55 ± 0.03 g) were evaluated over a 6-week feeding trial. The crude protein and lipid level of basal diet was targeted at 27% and 6%, respectively. Five levels of supplemented cholesterol (0, 0.25, 0.50, 0.75, and 1.00%) resulted in diets analyzed to contain 0.06, 0.29, 0.54, 0.81, and 1.05% cholesterol. Final weight, weight gain, feed intake, molting times, molting rate, chitinase mRNA expression and hemolymphatic LDL-C content significantly increased (P < .01) as the cholesterol supplementation level increased from 0.00 to 0.50%, and then significantly decreased (P < .05) as the cholesterol supplementation level increased from 0.50 to 1.00%. P. clarkii fed with 0.25% cholesterol supplementation and without cholesterol supplementation had significantly higher MIH expression level compared to P. clarkii fed with 0.50 and 0.75% cholesterol supplementation. Total cholesterol content in the hemolymph, hepatopancreas, and intestine, as well as hemolymphatic HDL-C content of P. increased significantly as the cholesterol supplementation increased from 0.00 to 1.00%. Taken together, the results presented here indicated that P. clarkii juvenile would grow better when fed with a 27% protein and 6% lipid diet supplemented with 0.50% cholesterol. The reason might be that more cholesterol transported from hepatopancreas resulted in the variation of ecdysteroid signal transduction, ultimately leading to increasing molting times in P. clarkii fed diets with 0.50% cholesterol supplementation.