Performance and fatty acid composition of surubim ( Pseudoplatystoma coruscans) fed diets with animal and plant lipids

Abstract

Four isonitrogenous (46% crude protein) and isolipidic (18.5%) diets were formulated using four different lipid sources: lard (diet 1); corn oil (diet 2); soybean oil (diet 3); and linseed oil (diet 4) to evaluate the performance and body composition of surubim . Ten fingerlings (mean weight, 2.75±0.2 g) were randomly assigned to net cages (60-l capacity). Triplicate groups were fed each test diet twice a day to apparent satiation for 63 days. No difference ( P>0.05) was observed for feeding performance. On the other hand, fatty acid composition of carcass lipids was affected ( P<0.05) by dietary lipid source. Palmitic (16:0) and oleic (18:1 n−9) acids were the major saturated and monoene fatty acids in the carcass and in the polar lipid fraction of liver lipids, independently of dietary lipid source. The total amount of saturated fatty acids was higher ( P<0.05) in the carcass of fish fed diet 1, which also showed higher levels of palmitic and oleic acids. Fish fed diets 2 and 3, showed the highest ( P<0.05) amount of n−6 fatty acids in their carcass and in the liver polar lipid fraction. Fish fed diet 4 showed the highest level of n−3 fatty acids in the carcass and of n−3 highly unsaturated fatty acids in the liver polar lipid fraction. The results indicated that both animal and plant lipids are well metabolized by this species and that it is possible to improve the n−3/ n−6 ratio of surubim meat by feeding various lipid sources.