Digestibility and Chemical Composition of “Oreochromis niloticus”, fed diets containing different phosphorus levels

Abstract

This study aimed to estimate the coefficient of aparent digestibility and determine the carcass chemical composition of Nile tilapia fingerlings (4.0 ± 0.4g) fed with diets containing different levels of phosphorus. A completely randomized design with four treatments and five replications was used. Diets with 28% digestible protein and 3000kcal DE / kg, containing 6% fish meal and surpassing the lysine / methionine ratio, supplemented with dicalcium phosphate in order to obtain levels of 0.27; 0.32; 0.37 and 0.42% available phosphorus. To determine the coefficient of digestibility of the diets, the feed was supplied four times a day which corresponds to 4% of body weight, for seven days. To determine the chemical composition of carcass, feed was supplied four times a day, at 7am, 10am, 1pm and 4pm. The feeding was manual and provided until apparent satiation, when capturing of food was not observed, nor regurgitation of food grains and there was presence of feed in the feeder. Significant difference was observed in levels of phosphorus over the digestibility of crude protein, dry matter and ether extract for tilapia fingerlings. There was no significant difference observed in available phosphorus levels in the diet over: crude protein, ash, calcium and water for carcass. However, there was significant reduction of body fat with the highest levels of phosphorus in the diet. Considering the results it is concluded that the diet with 0.27% available phosphorus was more digestible than the other treatments and diets with the level of 0.42% phosphorus provided better indicators of body composition.