EFFECTS OF DIFFERENT DIETARY SOYBEAN MEAL LEVELS ON TISSUE CHOLESTEROL STATUS AND MOLTING RELATIVE GENE EXPRESSION IN WHITE SHRIMP, Litopenaeus vannamei  

The study was to evaluate the effects of different dietary soybean meal (SBM) levels substituting to fish meal protein on growth, cholesterol status and molting relative gene expression in white shrimp, Litopenaeus vannamei. Diets supplemented with SBM replacing fish meal protein at 20 (SBM20), 40 (SBM40), 60 (SBM60), 80 (SBM80) and 100% (SBM100) were used as experimental diet. All fish meal diet was included as control. Total of 6 experimental diets were each fed to fed to triplicate groups of juvenile white shrimp (initial weight: 2.17 ± 0.05 g) in a recirculation rearing system for 8 weeks. Weight gain of shrimp fed with control and SBM20 diets were higher (P < 0.05) than that of shrimp fed with SBM80 and SBM100 diets. Cholesterol concentrations in whole body, hepatopancreas and hemolymph generally decreased by increasing dietary SBM levels. Hepatopancreatic ecdysteroid receptor gene expression was the highest in shrimp fed the control diet, followed by shrimp fed the SBM20 diet, and the lowest in shrimp fed SBM40, SBM 60, SBM80 and SBM100 diets. Shrimp fed control and SBM20 diets had the highest hepatopancreatic retinoic acid X receptor gene expression, followed by shrimp fed SBM40 and SBM60 diets, and the lowest in shrimp fed SBM80 and SBM100 diets. Chitin synthase gene expression was higher in shrimp fed control, SBM20 and SBM40 diets than other dietary treatments. Results indicated that dietary soybean meal supplementation reduced tissue cholesterol concentrations and molting relative gene expression for white shrimp.