Effects of Dietary Lipids on Growth, Food Conversion, Lipid and Fatty Acid Composition of Channel Catfish

Abstract

Channel catfish (Ictalurus punctatus) fingerlings were reared in 1-m-diameter fiberglass tanks at 26° and fed 27 experimental diets differing in source of lipid. Duplicate groups of fish were fed each of eight primary lipid sources and each lipid was fed at a level of 10% of diets in three molecular forms: triglyceride, free fatty acid, and ethyl ester. Highest average weights occurred when the fish were supplemented with beef tallow, olive oil and menhaden oil triglycerides. Substantially lower gains were obtained from groups fed short- and medium-chain fatty acids, a fat-free diet, safflower oil (high in 18:2ω6) and linseed oil (high in 18:3ω3). In general, triglyceride and ethyl ester diets led to more rapid growth of channel catfish than did free fatty acid diets. Food conversions for fish fed triglyceride diets were superior to those of fish on the other two dietary lipid types. The deposition of fatty acids in whole carcasses followed very closely the fatty acid composition of the diet whereas deviation from the dietary fatty acid composition was noted in liver.