Effects of Dietary Protein Concentration and l‐Carnitine on Growth, Processing Yield, and Body Composition of Channel Catfish × Blue Catfish F1 Hybrids

Abstract

AbstractA study was conducted in earthen ponds to evaluate effects of dietary protein concentration and l‐carnitine supplementation on feed consumption, weight gain, feed conversion ratio (FCR), processing yield, and body composition of hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish I. furcatus). Hybrid catfish fingerlings with a mean initial weight of 66 g/fish were stocked into twenty 0.04‐ha earthen ponds at a density of 17,290 fish/ha. Five ponds were randomly allotted to each dietary treatment in a complete randomized design. Fish were fed one of three practical diets containing 28, 32, or 36% crude protein without l‐carnitine and a 28% protein diet containing l‐carnitine at 500 mg/kg once daily to apparent satiation for a 151‐d growing season. Dietary protein levels ranging from 28% to 36% did not affect feed consumption, weight gain, or FCR of catfish hybrids fed to apparent satiation. Fish fed the 36% protein diet had a higher fillet yield than fish fed the 28% protein diet, whereas fish fed the 32% protein diet had intermediate fillet yield and fillet fat, which were not different from those of fish fed the 28% and 36% protein diets. The fillet fat concentration was lower in fish fed the 36% protein diet than in those fed lower‐protein diets. Supplementation of l‐carnitine at 500 mg/kg in the diet did not affect feed consumption, weight gain, FCR, or processing yield, but there was a trend toward a reduction in fillet fat level. Results from this study indicate that body fatness of channel catfish × blue catfish hybrids was reduced by feeding them a high‐protein (36%) diet and that l‐carnitine had a mild effect on fat reduction in hybrid catfish fed a 28% protein diet.