Evaluation of cholesterol additions to a soyabean meal-based diet for juvenile Pacific white shrimp, Penaeus vannamei (Boone), in an outdoor growth trial

Cholesterol is considered a required nutrient for penaeid shrimps, but an optimal level has not been defined. A 68-day grow-out trial was conducted in 1300-L outdoor tanks in Hawaii, USA, to determine the cholesterol level required in a soyabean meal-based diet for juvenile Pacific white shrimp, Penaeus vannamei (Boone). Test feeds were prepared by adding six cholesterol levels (1.0-10.2 g kg^?1, as-fed basis) to a standard diet high in plant-protein meals, starch and flour. These feeds were provided to the shrimp three times daily. Harvest weights and weekly growth increments varied significantly among diets. The 2.3 g kg^?1 and 4.2 g kg^?1 cholesterol diets yielded better growth than the 1.0 g kg^?1 and 10.2 g kg^?1 diets. Survival and feed conversion ratios did not vary significantly among diets. Significant dietary cholesterol effects on growth of P. vannamei in conditions resembling commercial grow-out indicate that its inclusion in practical diets at more accurately defined levels is necessary. Optimal cholesterol levels for juvenile shrimp may be lower than those now utilized, and may vary relative to the contribution of free sterols from natural foods in shrimp ponds.