GROWTH AND LIVER POLAR FATTY-ACID COMPOSITION OF YEAR-1 CHANNEL CATFISH FED VARIOUS LIPID SOURCES AT 2 WATER TEMPERATURES

Young channel catfish (Ictalurus punctatus) with an initial weight of 0.9 +/- 0.03 g were fed semipurified diets containing 7% lipids as bee f tallow, corn oil, linseed oil, menhaden oil, or a mixture (1:1:1) of menhaden oil, beef tallow, and corn oil at two water temperatures, 17 +/- 1-degrees-C and 28 +/- 0.5-degrees-C, for 9 weeks. At the higher temperature, fish fed the menhaden oil and the mixed-oil diets had gre ater weight gains (P < 0.05) than fish fed the other diets. Weight gai ns for fish fed beef tallow, corn oil, or linseed oil did not signific antly differ (P > 0.05). At the lower water temperature, weight gain w as much less, and the only significant difference among treatments was between the fish fed menhaden oil or mixed oil and those fed beef tal low, which gained no weight. The concentration of polyene fatty acids in liver phospholipids was higher at the low temperature than at the h igh temperature (P < 0.05). The primary n-3 highly unsaturated fatty a cid (HUFA) in liver phospholipids of fish fed menhaden oil or the mixe d oils was 22:6 n-3, docosahexaenoic acid (DHA). Fish fed corn oil had primarily 20:4 n-6, arachidonic acid (AA), in their phospholipids, an d those fed linseed oil had a small amount of 20:5 n-3, eicosapentaeon ic acid (EPA), but no DHA in their liver phospholipids. This study ind icates that the presence of fish oil, a source of n-3 HUFA, in the die t enhances growth of young channel catfish at optimum and suboptimum t emperatures.