Effects of dietary n-3HUFA on juvenile white shrimp, Litopenaeus vannamei: Growth, feed utilization, antioxidant enzymes activities and fatty acid compositions

Abstract

Present study investigates the effects of n-3 high-unsaturated fatty acid (n-3HUFA) levels on growth performance, antioxidant enzymes activities and fatty acid compositions of juvenile Litopenaeus vannamei. These represented seven iso-nitrogenous and iso-lipidic diets. Analysed n-3HUFA concentrations were 0.16% (control), 0.48%, 0.74%, 1.39%, 2.39%, 2.92% and 3.44% respectively. A total of 840 juvenile L. vannamei were randomly stocked into 21 0.5 m3 tanks for 56 days. A significant increase (p < 0.05) was observed from 0.16% to 0.74% n-3HUFA and a decrease when n-3HUFA was above these levels in weight gain rate (WGR) and specific growth rate. Total cholesterol, triglyceride and low-density lipoprotein in serum showed a significant decrease, high-density lipoprotein showed a significant increase (p < 0.05). Phenoloxidase activity in serum and sodium-potassium adenosine triphosphatase activity in gill were significantly affected by dietary n-3HUFA (p < 0.05), both of them showing a downward trend after upward. Malic dehydrogenase and superoxide dismutase activities in serum were also significantly affected by dietary n-3HUFA (p < 0.05), which rose first and then decreased in general, both of them have a maximum in 2.39% group. No significant differences of the activities of aspartate transaminase and alanine transaminase were observed among all groups (p > 0.05). With dietary n-3HUFA increase, both ∑HUFA and n-3HUFA contents gradually increased in hepatopancreas and tail muscles (p < 0.05). Based on broken-line regression analysis of WGR, the optimal n-3HUFA requirement is 0.89% for juvenile L. vannamei with initial weight of 0.50 ± 0.01 g.