Utilização de fitase para tilápia-do-Nilo

Abstract

This research aimed to evaluate the effects of different phytase levels on performance and digestibility in diets for Nile tilapia in two stages of development. Were used in the first phase 400 Nile tilapia fingerlings with initial weight of 35.68 ± 1.41 g; in the second phase 300 juveniles with weight of 118.06 ± 5.19g, distributed in 20 cages put in 4 masonry tanks. Commercial foods were used with 31% CP in the first phase and 26% CP in the second one. The treatments were 0, 500, 1000, 1500 and 2000 active phytase unity (APU) per kg of diet for both phases. Were determined apparent digestibility coefficients of protein, energy and phosphorus; chromium oxide III was used as a marker. For the digestibility trial, were used 20 incubators adapted for feces collect. For evaluating the performance, were evaluated medium final weight, apparent feed conversion and medium weight gain. The design was in randomized blocks with five treatments and four replications. There was no significant effect of the use of phytase enzyme to the level of 2000 APU / kg of diet on the productive performance parameters for both phases. Concerning to apparent digestibility coefficients (CDa) of protein, gross energy and phosphorus in the first phase, variance analyses showed no significant difference. The averages found for feed conversion were very high, being harmful to fish development and increasing the cost of food, showing that the commercial feed used in this experiment has a low nutrient utilization. For the values of CDa of protein, gross energy and phosphorus were not found statistical differences in the second phase. Under the conditions that this experiment was carried out, it is possible to conclude that phytase did not affect the performance and digestibility of protein, energy and phosphorus in the two phases of Nile tilapia development.