Effect of phytase supplementation on growth performance, body mineral composition, and effluent phosphorus content of the seabream (Sparus aurata)

This study evaluated the effects of the dietary phytase on growth, feed utilization, body chemical composition, body minerals composition, and effluent phosphorus (P) content in sea bream (Sparus aurata). Treatment 1 (the control group) contained mineral premix (MP) and inorganic phosphorus (IP) (mono-calcium phosphate) at concentrations of 6 g and 5 g kg‒1 diet, respectively, without the addition of phytase. The other four treatments contained one level of dietary phytase supplementation at 0.2 g kg‒1 (5000 FTU kg), in the presence or absence of MP and IP, separately or in combination, at concentrations of 6 g and 5 g kg‒1 diet, respectively. Sea bream (S. aurata) (0.32±0.01 g fish‒1) (initial mean weight ± SD) fed the experimental diets for 60 days. Growth and feed utilization were significantly enhanced by dietary phytase-supplemented diets. Final weight, weight gain, average daily gain, specific growth rate, feed intake, and protein efficiency ratio were higher in the phytase-containing treatments than in the control diet, regardless of the presence or absence of mono-calcium phosphate or the mineral mixture. Following the same pattern, the feed conversion ratio was better in the phytase-containing treatments than in the control diet. Body crude protein, ash, and mineral composition were significantly increased by the dietary inclusion of phytase regardless of the presence or absence of IP or MM. Furthermore, the addition of phytase into S. aurata diets reduced the phosphorus concentration in their effluents. Thus, this study emphasizes the important role of the dietary phytase in S. aurata in enhancing the growth performance, enriching the body's nutritional composition, and reducing the environmental impacts of fish farming.