The Effects of Diets Containing Standard Soybean Oil, Soybean Oil Enhanced with Conjugated Linoleic Acids, Menhaden Fish Oil, or an Algal Docosahexaenoic Acid Supplement on Juvenile Channel Catfish Performance, Hematology, Body Composition, and Nonspecific Immune Response

To reduce diet cost and address environmental concerns, current commercial diets for Channel Catfish Ictalurus punctatus contain little or no marine fish oil. However, there are conflicting data on the effects of fish oil and other lipid sources for juvenile Channel Catfish, and some novel lipids have not been tested against traditional ones. In this study, the effects of four different lipid sources for potential use in juvenile Channel Catfish diets were investigated by measuring fish growth performance, proximate and fatty acid composition of muscle, nonspecific immune response, and hematological parameters. In a 63-d feeding trial, juveniles (mean weight +/- SE = 11.2 +/- 0.0 g) were fed a commercial 32% protein diet supplemented with 2% lipid from standard soybean oil (SBO; control diet), SBO enriched with conjugated linoleic acids (CLAs; CLA diet), algal (Schizochytrium sp.) docosahexaenoic acid (DHA) extract (DHA diet), or menhaden fish oil (MFO diet). Fish that were fed the MFO diet had improved feed conversion compared with fish that were fed the SBO, CLA, or DHA diet. There were no other differences in fish growth performance or proximate composition and no differences among treatments in nonspecific immune responses or hematological parameters. As expected, fatty acid composition of fish muscle reflected that of the diets: fish that received the MFO, DHA, or CLA diet contained higher levels of healthful fatty acids (DHA or CLAs) than fish that were given the SBO control diet. Future trials will address methods for (1) increasing target levels of these fatty acids by using diets with little or no fish oil and (2) optimizing retention of desirable fatty acids to facilitate the production of Channel Catfish as a high-value functional food.