Effects of arginine, phenylalanine and tryptophan deficiency in diets on growth factors and whole body proximate of Sobaity seabream juvenile (Sparidentex hasta)

On this study effects of reducing arginine, phenylalanine and tryptophan amino acids in diets of Sobaity seabream in a constant level (40%) on growth, nutritional indices, whole body chemical proximate and amino acids, was assessed. For these purposes four different treatments in triplicate was used during 42 days in base of feeding with semipurified diets containing crystalline amino acids. The control diet was without any deficiency, the arginine (ARG), phenylalanine (PHE) and tryptophan (TRP) diets were deficient in arginine, phenylalanine and tryptophan respectively. Crystalline amino acids were used to formulate diets precisely with desired amounts of deficiency. In fish fed ARG diet, just two factors including nitrogen retention and percentage of weight gain decreased in comparing with control group (P > 0.05). But in PHE and TRP treatments all the growth and nutrition factors including final weight, weight gain, specific growth rate, feed consumption, protein efficiency and nitrogen retention decreased significantly regarding to the control group (P > 0.05). The experimental treatments affect whole body proximate regarding to the control by increasing whole body moisture in PHE, reduction of gross energy in all treatments and reduction of Crude lipids in TRP and PHE (P > 0.05). Reduction of whole body protein in ARG treatment showed using more protein rather than lipids as a source of energy in this group of fish. Reduction of whole body lipid in all treatments regarding to the control group showed some disorder in lipid metabolism. In spite of arginine, phenylalanine and tryptophan deficiency in diets, the amounts of these amino acids in fish whole body did not decreased that showed amino acids sparing effect for these three essential amino acids happened in fish body. The results of the current study showed that reduction of one single essential amino acid from diet have strong effects on other amino acids retention and consequently reduces protein synthesis and growth.