Assessment of a high protein distillers dried grain (HP-DDG) augmented with phytase in diets for European sea bass, Dicentrarchus labrax fingerlings on growth performance, haematological status, immune response and related gut and liver histology

Inclusion of high levels of plant protein ingredients in fish feeds induces the presence of undesirable compounds such as Anti-Nutritional Factors, including non-starch polysaccharides and phytates. The present study evaluated the effect of partial replacement of dietary soybean meal by a high protein distillers dried grains (HP-DDG) a co-product of corn based ethanol production. We evaluated HP-DDG in experimental diets with a supplemented commercial phytase on growth performance, physiological parameters and histological changes of the intestine and liver of European sea bass, Dicentrarchus labrax fingerlings. The experiment was conducted for six weeks. A total of 240 D. labrax fingerlings was randomly divided to four experimental treatments (each in triplicates groups) and fed to apparent satiation six days per week for a six weeks’ period. Four dietary treatments: containing 0, 30, 40 and 50% HP-DDG supplemented with enzyme phytase 0.5g kg-1 diet respectively, were tested. The results showed that growth performance and feed utilization efficiency of sea bass was significantly higher (P≤0.05) with increasing levels of HP-DDG-and phytase supplementation. Superior phosphorous utilization was also observed with respect to whole body retention for each incremental level of HP-DDG inclusion. Hematology and serum biochemistry (hemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs) and humoral immune parameters including total protein, globulin, cholesterol, lysozyme activity and total antioxidant capacity (TAC) were improved (P≤0.05) in fish fed diets with increased levels of HP-DDG and supplemented phytase. The findings suggest that the use of HP-DDG supplemented with phytase in sea bass diets enhanced growth, physiological and immunological responses, and evidenced a cost benefit advantage for European sea bass production compared to the use of a diet without either HP-DDG or phytase incorporation