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University of Georgia College of Agriculture, Skidaway Institute of Oceanography, and Coastal Plain Station, P.O. Box 13687, Savannah, Georgia 31406
Semipurified diets with casein as the sole protein source were supplemented with gelatin, arginine, cystine, methionine or tryptophan, and fed to channel catfish (Ictalurus punctatus) fingerlings. Increasing the arginine level from 1.1% to 1.7% of diet by the isonitrogenous substitution of gelatin for casein resulted in a significant enhancement of growth. However, the addition of free arginine, cysteine, tryptophan or methionine to casein had little effect on growth or food conversion. These data substantiate a previous report that suggested catfish were similar to carp in their inability to utilize free amino acids.
KEY WORDS: catfish casein gelatin arginine cystine methionine
1 This investigation was partially financed by a grant from The Fats and Proteins Research Foundation, Des Plaines, Illinois 60018.
Manuscript received 13 December 1976.