Phosphorus availability of inorganic phosphates and fish meals in European sea bass (Dicentrarchus labrax L.) juveniles

A trial was conducted to evaluate the apparent availability of phosphorus (P) of five fish meals and three inorganic phosphorus sources (mono-, di- and tricalcium phosphate) to European sea bass juveniles.A corn gluten based diet containing 0.2% P was used as the basal diet. Test diets were formulated with different proportions of basal diet and test ingredients in order to have final phosphorus levels of 0.5%. This level was used as it is marginally lower than the estimated P requirement of sea bass, aiming that P availability is not affected by excessive dietary P concentration. Moreover, three other test diets were formulated to include only 0.3% of inorganic P sources, to evaluate the effect of dietary P levels on availability.ADC of P of fish meals ranged from 49 to 63% and was generally related to the fish meal ash content. Within the inorganic phosphorus sources, ADC of P was not affected by dietary phosphorus level but was significantly affected by supplement source. Mean P availability decreased in the following order: dicalcium phosphate (68%) > monocalcium phosphate (56%) > tricalcium phosphate (50%).