Evaluation of glutamine supplementation in the diet on the structure and function of the intestine and the growth performance of African catfish, Clarias gariepinus (Burchell 1822) juvenile

Abstract

A triplicate experiment was conducted to evaluate the effect of the diet supplemented with free glutamine (Gln) on intestinal structure and function, as well as the growth performance of African catfish Clarias gariepinus juvenile. The commercial feed was supplemented with Gln of either 0% (control), 0.7%, 1.4% or 2.1%. Fish measuring 2 ± 0.02 cm were stocked in 12 aquariums 50x40x35 cm filled with water at a volume of 50 L with a density of 2,000 fish m-2. Fish were cultured for 30 days and fed on the diets three times a day at satiation. Results showed that the growth rate and biomass of the fish at the end of the experiment had a quadratic response, with the maximum growth achieved at 0.7% Gln treatment. The response pattern of fish growth was in line with the distribution of fish length. Fish in 0.7% Gln treatment had number fish measuring 5-6 cm more than 12% less than other treatments, while fish measuring 7-8 cm were more than other treatments. Higher growth in the 0.7% Gln treatment correlated with longer villi, higher protein retention, and ultimately higher feed efficiency. Increased intake of Gln in the diet also caused an increase in intestinal protease enzyme activity, and accumulation of Gln in the liver, but did not increase the enzymes activity of the liver Superoxidase Dismutase (SOD). It can be concluded that feeding on a diet supplemented with 0.7% Gln can improve the structure and function of the intestine, as well as increase the target size of catfish juvenile production.