Evaluation of Dietary Protein Level in Practical Feed for Twoband Bream Diplodus vulgaris

Abstract

The effects of different dietary protein levels on growth performance and health status of TwobandBream Diplodus vulgaris juveniles were investigated. Three test diets that had increasing protein levels (30, 36, and 42%) and used fish meal as the protein source were formulated. Each of the test diets was fed in triplicate groups of 28 juvenile fish (initial weight, 23.65 ± 0.34 [mean ± SD]) to satiety for a period of 80 d. Growth performance and feed utilization were best in the group fed the diet with a protein level of 36%. Ammonia nitrogen excretion showed an increasing trend as dietary protein levels increased, and retention rates of ammonia nitrogen per intake were highest in fish fed the 42% protein diet. Whole-body proximate composition and hematological variables were not significantly affected by protein level in the diets. However, serum glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) values were significantly affected by dietary protein level and showed an increasing trend as the dietary protein level in the diets increased. As a result, an improved health status of Twoband Bream was observed in the fish fed a 36% protein level.