Dietary phosphorus requirement of juvenile milkfish, Chanos chanos (Forsskal)

Abstract

Seven isocaloric and isonitrogenous diets with graded levels of monopotassium phosphate to yield total phosphorus levels of 0.28 (no P supplementation), 0.43, 0.58, 0.73, 0.88, 1.03 and 1.18% were prepared and fed to five replicate groups of 10 juvenile milkfish (initial weight = 2.5 g). After 16 weeks of feeding, significant differences in growth (300–570%), survival rates (70–100%), and bone and scale mineralization were found among treatment groups. Weight gains of milkfish increased linearly up to the 0.88% dietary phosphorus concentration and levelled off beyond this dietary level. Bone and scale ash, calcium and phosphorus concentrations showed similar patterns as weight gain in response to dietary phosphorus concentration. Broken-line regression analyses of these data indicated that the dietary phosphorus level required for optimal growth and mineralization of juvenile milkfish is ≈ 0.85% of dry diet.