CHOLESTEROL REQUIREMENT IN SEMI-PURIFIED DIETS OF JUVENILE PACIFIC WHITE SHRIMP Litopenaeus vannamei

Cholesterol cannot be synthesized by crustaceans ; hence, it is an  essential nutrient  which is critical for the synthesis of numerous compounds. S tudies  pertaining to  cholesterol requirement  are limited based on the levels' evaluated as well as statistical analysis. Hence,  the objective of the study was to confirm and refine the cholesterol requirement and to provide preliminary data on the efficacy of phytosterol(s) as a substitute for cholesterol  in Pacific white shrimp Litopenaeus vannamei feeds. T he basal diet was supplemented graded levels of cholesterol (0, 0.04, 0.08, and 0.12%)  analysis confirmed cholesterol ranged from 0.048 to 0.185% . A 6-week period using shrimp with initial weight of 0.24g reaching a final weight  of 3.68 to 6.86 g or percent weight gain from 1522 to 2640% (n=5).  The growth response was very linear with no clear plateau in growth. Hence, a follow up trial was  conducted to refine the response . Eight diets were designed  with an increased  range of cholesterol level from 0.045 to 0.457% of diets. In addition, two levels of  un-esterified  phytosterol supplements (0.06, 0.12%) were also evaluated. Each diet was fed to 4 replicate groups of juvenile shrimp (0.38g initial weight) for 6 weeks reaching a final weight of (4.31-7.43g) or percent weight gain from 1014-1874%.  Saturation kinetic model, broken line models with linear or quadratic ascending portions, were used to evaluate dose-response relationships of feed efficiency (FE), thermal-unit growth coefficient (TGC) , body cholesterol (BC) , body cholesterol deposition (BCD) and body cholesterol deposition efficiency (BCDE) against dietary cholesterol. The cholesterol requirement of juvenile shrimp was estimated at 0.19 % [0.11-0.43%] , 0.17% [0.11-0.33%] , 0.25% [0.23-0.29%], 0.27% [0.24-0.31%]  and 0.17% [0.14-0.21%]  of shrimp diet for FE , TGC , BC,  BCD and BCDE,  respectively.  Those results with phytosterol also indicated  reasonable biological availability which  may allow partial replacement for cholesterol.