Dietary Phosphorus Requirements of Juvenile Hybrid Tilapia (Oreochromis niloticus♀× O. Aureus♂) Fed Fishmeal-free Practical Diets

Abstract

A growth trial was conducted to estimate the optimum levels of dietary phosphorus (P) for juvenile hybrid tilapia (Oreochromis niloticus × O. aureus) fed fishmeal-free practical diets. Hybrid tilapia (1.68 ± 0.08 g) were fed diets containing various levels (0.0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0%) of additional inorganic phosphorus for 10 weeks using two different sources of phosphorus：calcium dihydrogen phosphate (MCP), and sodium dihydrogen phosphate (MSP). Hybrid tilapia fed the P-supplemented diets showed significantly higher weight gain (WG) and mineral deposition than those fed the unsupplemented diet. Based on weight gain and vertebral phosphorus content, the available phosphorus requirements of hybrid tilapia were estimated as 1% and 1.31% (0.6% and 0.9% based on additional phosphorus content) respectively, when MSP was used as a phosphorus source. When MCP was the phosphorus source, the requirement estimated for weight gain was 0.95% (0.61% based on additional phosphorus content). In addition, MCP contributed to increased growth and a higher mineral deposition rate than did MSP, in freshwater-reared hybrid tilapia.