Effect of dietary L-arginine on growth performance and physiological responses of Nile tilapia, Oreochromis niloticus

Abstract

A feeding trial was conduct to investigate the effect of dietary supplementation of L-arginine on growth performance, feed utilization, hemato-biochemical parameters and hepatic antioxidant enzymes activity of Nile tilapia, Oreochromis niloticus for 70 days. Three isonitrogenous and isocaloric diets (310.9 g kg-1 crude protein and 18.93 MJ kg-1 gross energy) were formulated. Each diet was supplemented with L-arginine at levels; 0.0 (control), 4.0 and 8.0 g kg–1 diet. After 70 days the obtained results were as following, the highest weight gain, specific growth rate, protein efficiency ratio and the best feed conversion ratio were recorded in fish fed 8 g L-arginine kg–1 diet. As well as, the addition of L-arginine significantly (P < 0.05) improved hemoglobin, hematocrit, red blood cells, white blood cells and total protein values compared with the control diet. On the other hand, the addition of L-arginine significantly (P < 0.05) decreased values of alanine aminotransferase and aspartate aminotransferase in fish fed 8 g L-arginine kg–1 diet. Also, the addition of L-arginine significantly (P < 0.05) enhanced the hepatic superoxide dismutase activity and total antioxidant capacity level while; malondialdehyde concentration was significantly (P < 0.05) decreased with addition of L-arginine up to 8.0 g kg–1 diet. Based on the obtained findings, it could be conclude that the valuable impacts of addition L-arginine up to 8.0 g kg–1 diet in enhancement the growth performance, feed utilization hemato-biochemical parameters and hepatic antioxidant enzymes activity of Nile tilapia O. niloticus.