Growth response and fatty acid composition of juvenile Penaeus vannamei fed different sources of dietary lipid

Abstract

A study was conducted to evaluate the effects of feeding various sources of dietary lipid on weight gain, feed conversion, survival and fatty acid composition of juvenile Penaeus vannamei. Seven semi-purified diets (35% protein and 3400 kcal of metabolizable energy kg −1) containing defatted, freeze-dried shrimp meal, 1.0% soybean lecithin and 0.5% cholesterol were supplemented with 6.5% of either stearic acid, coconut, safflower, corn, soybean, linseed or menhaden fish oils. Each diet was fed to shrimp (1.00 ± 0.03 g average weight) in four replicate aquaria four times daily for 10 weeks. Weight gain, feed conversion and survival were best for shrimp fed the diet containing menhaden fish oil. Shrimp fed the linseed oil diet had the second highest weight gain, followed by shrimp on soybean oil, corn oil, stearic acid, coconut oil and safflower oil diets, respectively. Feed conversion values were a reflection of weight gain. Results of this study show that both n-6 and n-3 fatty acids are dietary essential for juvenile Penaeus vannamei, although n-3 fatty acids promoted faster growth than n-6. However, highly unsaturated fatty acids (HUFA) (20:5 n-3 and 22:6 n-3) had better growth-promoting effect than 18:3 n-3, due probably to the limited ability of shrimp to bioconvert fatty acids to polyenoic forms of longer chain length. The fatty acid composition of the shrimp generally reflected that of the dietary lipids, especially for the diets containing unsaturated fatty acids. Shrimp fed stearic acid and coconut oil diets low in polyunsaturated fatty acids accumulated high levels of 16:1 n-7 and 18:1 n-9.