Assessment of cholesterol requirements in the prawn, Penaeus japonicus

Two feeding experiments were conducted to assess the quantitative cholesterol requirement of the juvenile prawn, Penaeus japonicus. The prawns were fed casein‐based (experiment 1) and casein‐ or crab protein‐based (experiment 2) diets with or without supplemental cholesterol. The daily increases in quantities of body cholesterol (mg kg−1prawn day−1) at maximum growth and dietary cholesterol intake over a 40‐day feeding period were determined. Prawns fed 5 g kg−1supplemental cholesterol, regardless of protein sources, gave the highest weight gain. Body retention efficiencies of dietary cholesterol (cholesterol retained × 100/cholesterol intake) vary among prawns fed 5 g kg−1supplemental cholesterol (diets 3, 5 and 7) but dietary cholesterol requirements expressed as mg kg−1body weight (BW) day−1were not significantly different (180 to 200 mg kg−1BW day−1). Based on dietary cholesterol requirement, the optimum dietary cholesterol levels for the juvenile prawns were estimated in relation to feeding levels. When feeding levels were 3%, 5% and 7% of body weight, optimum dietary cholesterol levels were 5.0 to 6.0, 3.6 to 4.0, and 2.6 to 2.9 g kg−1of dry diet, respectively. The present study showed the advantages of determining daily cholesterol requirement (mg kg−1BW day−1) at maximum growth through a factorial method in determining optimum dietary cholesterol levels in P. japonicus.