AVAILABILITY OF PHOSPHORUS IN FISH BONE MEAL AND INORGANIC SALTS TO ATLANTIC SALMON (SALMO-SALAR) AS DETERMINED BY RETENTION

The availability of phosphorus to juvenile (5.6 g) Atlantic salmon fro m primary and secondary calcium phosphate, primary sodium phosphate an d fish bone meal was determined by measuring retention of P in a 12-we ek feeding trial. Semi-purified casein-based diets were fed and dietar y P concentrations were slightly below the requirement. An unsupplemen ted basal diet (4.6 g kg(-1) P) and a presumed P sufficient diet (prim ary calcium phosphate, 11 g kg(-1) P) were also fed. Whole body P conc entrations declined in fish fed the deficient diets indicating that th e fish utilized all the available P. Retention of the P sources was: b asal diet, 72%; primary calcium phosphate, 86%; secondary calcium phos phate 91%; primary sodium phosphate, 131%; and fish bone meal, 51%. Ou r results indicate that the inorganic P salts had higher availability than P from fish bone meal. The high retention of primary sodium phosp hate was attributed to improved availability of P in the basal diet, O ur results also indicate that P availability may not be additive when P is present in a diet from multiple sources. (C) 1997 Elsevier Scienc e B.V.