Effect of dietary phospholipid on essential fatty acid requirements and tissue lipid composition of Litopenaeus vannamei juveniles

Abstract

A 6-week study was conducted to evaluate the effect of dietary phospholipids (PL) on essential fatty acid requirements of juvenile Litopenaeus vannamei and their potential interaction. A 3×3 factorial experiment was carried out with increasing levels of soybean lecithin as the dietary PL (0%, 1.5% or 3% of diet). Three dietary levels (0%, 0.25% or 0.5% of diet) of docosahexaenoic acid (22:6 n−3, DHA), or an n−3 highly unsaturated fatty acid (HUFA) mixture containing 416 mg eicosapentaenoic acid (EPA)/g and 237 mg DHA/g were tested. No significant interactions between the effects of PL and DHA or n−3 HUFA on growth were detected under these experimental conditions; however, instantaneous growth rate (IGR) of shrimp was enhanced by addition of either DHA or n−3 HUFA at 0.25% of diet. A higher dietary inclusion level (0.5% of diet) did not further improve growth, and appeared to have a detrimental effect on survival of shrimp. Also, an inclusion level of 3% dietary PL significantly improved IGR of shrimp, and did not show a significant effect on survival. PL supplementation did not consistently increase the proportion of phosphatidylcholine or other PL in shrimp muscle. The proportion of linoleic acid decreased as dietary DHA or n−3 HUFA increased. Thus, these results corroborate the beneficial effects of dietary PL on growth of shrimp, as well as their requirement for DHA and n−3 HUFA to achieve maximum growth.