Effect of Dietary Protein on Growth

Abstract

The captive breeding of the Silver catfish Schilbe intermedius was envisaged to promote the aquaculture and to reduce the overfishing of this endangered species. S. intermedius fingerlings were fed various dietary protein levels to investigate their growth performance, feed utilization and carcass proximate composition. Fish meal and casein were the sources of protein used in the study. Six isocaloric experimental diets containing 25%~60% crud protein (CP) diet have been  fed to three-replicate six groups of forty (40) fishes (mean weight: 1.640 ± 0.015 g) for 8 weeks. Both percent weight gain and feed efficiency ratio significantly increased with increasing dietary protein levels up to 45%, while there were no significant differences for protein levels from 45 to 60%. Growth performances and nutrient utilization parameters of fingerlings fed different diets varied significantly (P < 0.05) and the highest growth performance and nutrient utilization were obtained with fish fed on a 45% CP diet. The second order polynomial regression between dietary protein and specific growth rate (SGR) indicated that protein requirements of S. intermedius fingerlings ranged from 42.5 to 53% of diet. The highest protein content of the fish carcasses was found in fish fed 45% dietary protein and there was not significantly different (P > 0.05) with that of fish fed 60% dietary protein. Lipid content increased with increasing dietary protein levels. The dry matter and protein content of the initial sample were significantly higher (P > 0.05) than the values after feeding the fish with experimental diets.