Use of Crystalline Amino Acids Coated with Casein in Diets for Carp

Abstract

Crystalline amino acids coated with casein as a supplement to gelatin or casein and four kind of carbohydrates with different molecular size (glucose, maltose, dextrin and alpha-starch) were fed to fingerling carp for 6 weeks to test a hypothesis that the poor utilization of crystalline amino acids by carp may be due to rapid absorption of certain amino acids. Fish fed with the gelatin diet supplemented with 10 amino acids coated with casein showed comparable growth to that of the control diet (25% casein, 10% gelatin and 30% alpha-starch) with which the fish achieved 378% weight gain in 6 weeks, and more than four-fold faster growth rate and almost two-fold better feed efficiency than the fish fed with the gelatin diet supplemented with the same 10 amino acids but uncoated. There was no significant differences in growth and feed efficiency among fish fed with glucose, maltose, dextrin and alpha-starch. Addition of either coated or uncoated arginine to casein, improved growth and feed efficiency, but there was no significant difference between the two groups. These results may indicate that coating amino acids with casein minimized variation in absorption rate of amino acids, which resulted in relatively simultaneous availability of all amino acids to the tissues for optimal protein synthesis. Whereas, differences in absorption rate among glucose, maltose, dextrin and starch may not have shown any significant effect on the growth or feed efficiency, because glucose is the only basic building block of carbohydrates used in this study. © 1981, The Japanese Society of Fisheries Science. All rights reserved.