Growth Performance, Biochemical Responses, and Skeletal Muscle Development of Juvenile Nile Tilapia, Oreochromis niloticus, Fed with Increasing Levels of Arginine

Tilapia, Oreochromis niloticus, is among the fish species with high potential for aquaculture in intensive farming, and Brazil is among the largest producers worldwide. Some of the amino acid requirements in practical diets for tilapia are still unknown. Thus, this study determined the dietary arginine requirements for Nile tilapia juveniles based on growth performance, hematological and biochemical responses, and muscle growth. Three hundred Nile tilapia juveniles (2.95 +/- 0.79g) were distributed into 20-500L fiberglass aquaria and fed five extruded isoproteic (28% crude protein) and isoenergetic (3160kcal/kg) diets formulated to contain 0.95, 1.10, 1.25, 1.40, and 1.55% arginine. Based on the quadratic regression analysis, the best results in weight gain, feed conversion, protein efficiency ratio, and protein retention were estimated in fish fed diets containing 1.36, 1.34, 1.36, and 1.37% arginine, respectively. The best amino acid body retention values were estimated in fish fed diets containing 1.31-1.37% arginine. Muscle growth occurred mainly by hyperplasia in fish fed 0.95% arginine, whereas reduction in the hyperplasia time and signs of hypertrophy occurred in fish fed 1.10-1.55% arginine diets. It was concluded that a diet with 1.36% of arginine (with 1.53% lysine in diet) meets the requirements of Nile tilapia juveniles.