Study of the requirements of dietary cholesterol at two different growth stages of Pacific white shrimps, Litopenaeus vannamei

摘要

Two 8-week feeding experiments were conducted to investigate the cholesterol requirements of Litopenaeus vannamei at two different growth stages-with initial body weights of 0.61 +/- 0.00 g (juvenile) and 4.25 +/- 0.00 g (subadult). Six diets containing cholesterol (C) 0.03% (FM-fish meal), 0.09% (0.05% C), 0.14% (0.1% C), 0.27% (0.2% C), 0.47% (0.4% C), and 0.90% (0.8% C) were prepared with red fish meal, dehulled soybean meal and peanut meal as the protein source, and fish oil as the fat source. Two levels of phytosterol (P) substitutes-0.05% (0.05% P) and 0.8% (0.8% P)-for dietary cholesterol were evaluated. Results showed dietary cholesterol levels had significant effects on the weight gain rate (WGR), specific growth rate (SGR), and feed conversion ratio (FCR) of juveniles (P < 0.05). Crude fat in the 0.05% C and 0.1% C groups of subadults was significantly higher than that in the FM group (P < 0.05). The contents of CHOL, HDL, LDL, and liver CHOL were significantly associated with the content of cholesterol (P < 0.05). The dietary cholesterol proportion significantly affected serum AST and ALT (P < 0.05). Phytosterol supplementation presented growth-promoting effects for juvenile L. vannamei. A broken-line equation for weight growth showed the optimum dietary cholesterol requirement was 0.16% for L. vannamei juveniles (0.61 +/- 0.00 g), and no extra dietary cholesterol supplementation was needed for L. vannamei subadults (4.25 +/- 0.00 g).