Effects of dietary lipids, dietary protein and environmental temperatures on growth, feed conversion and body composition of channel catfish.

Studies were conducted to determine the effects of several lipid supplements in practical-type diets for channel catfish (Ictalurus punctatus) fingerlings reared at 23 degrees and 28 degrees. Maximum growth and feed efficiency were obtained when diets were supplemented with 9% animal tallow, 9% menhaden oil or a combination of the two (4.5% of each). A growth suppression was observed when fish were fed a diet containing a combination of 3% corn oil, 3% animal tallow and 3% menhaden oil. In studies on interactions of dietary protein and lipid at 23 degrees and 28 degrees, increasing dietary protein from 25% to 35% resulted in higher gains. At 28 degrees, increasing dietary lipid from 5% to 12% resulted in increased gains with diets containing 35% protein but not withdiets containing 25% protein. At 23 degrees, 5% lipid was sufficient in all cases. Carcass lipid levels increased with increasing temperature and were positively correlated with weight gains and negatively correlated with carcass moisture content. Improved protein conversion (protein fed: protein gained) was noted when dietary protein levels were increased from 25% to 35%; when dietary lipid levels were increased from 5% to 12%; and when environmental temperature was increased from 23 degrees to 28 degrees.