Lipid nutrition of juvenile Litopenaeus vannamei I. Dietary cholesterol and de-oiled soy lecithin requirements and their interaction

Two 6-week experiments were conducted in recirculating systems to determine dietary requirements of Litopenaeus vannamei for phospholipids (PL) and ch olesterol, and their potential interaction. A 3 X 4 factorial design consis ting of three cholesterol levels (0%, 0.2%, and 0.5% of diet) and four PL l evels (0%, 1.5%, 3.0%, and 5.0% of diet) provided by de-oiled soybean lecit hin (SL) was applied. Overall survival was 97.7% with no significant differ ence among dietary treatments. There was a highly significant interaction b etween PL and cholesterol on shrimp growth (P = 0.0001) Dietary cholesterol at 0.2% or 0.5% gave similar shrimp growth at any given level of FL. In a second factorial experiment, the same four levels of PL were evaluated in conjunction with smaller intervals between dietary cholesterol levels, 0%, 0.05%, 0.1%, 0.2%, and 0.4%, in an attempt to define dietary requiremen ts and interaction better. Overall survival was 99.7%. A highly significant interaction between dietary PL and cholesterol on growth of shrimp was det ected again (P = 0.0001). The cholesterol requirement was estimated to be 0 .35% of diet in the absence of supplemental FL. At 1.5% and 3% FL, dietary cholesterol requirements were reduced to 0.14% and 0.13% of diet, respectiv ely. When PL were provided at 5% of diet, 0.05% dietary cholesterol was nee ded for optimal growth. Shrimp growth was significantly enhanced as level o f PL increased, but as the level of dietary cholesterol level increased, th e growth-promoting effect of PL was diminished. Lipid composition of hepato pancreas (mid-gut gland) and muscle tissue of shrimp fed the different diet s was also analyzed. Diets supplemented with PL resulted in higher total li pid in hepatopancreas and lower total lipid in muscle of shrimp than those of shrimp fed diets without supplemental FL. Interaction between dietary PL and cholesterol also affected total lipid and triglycerides (TG) in the he patopancreas, as well as cholesterol concentration in the muscle. (C) 2000 Elsevier Science B.V. All rights reserved.