Protease exógena em ração para tilápia-do-Nilo

Abstract

This work aimed to evaluate the protease enzyme supplementation on performance and digestibility of feed nutrients for Nile tilapia. We used 408 Nile tilapia, with initial weight of 90.22 ± 14.97 g. Two trials were set, one to evaluate the performance and another to determine the digestibility of feed's protein and energy. The experiment of productive performance lasted 60 days. The fish were distributed in 24 cages, with 17 fish by experiment unit. It was used ration with plant and animal ingredients, supplemented with five levels of protease enzyme, composing six treatments (without addition of protease; 0.01; 0.02; 0.04; 0.08; 0.16% protease). At the end of the trial period we determined the average parameters of final weight, weight gain, apparent feed intake and apparent feed conversion. The experiment to determine the digestibility coefficients lasted five days. On the 40th day of the performance experiment, all of the fish were transferred from cages to 24 incubators, adapted for feces collection by gravity. The determination of the coefficients was performed using the indirect method with 0,1% chromium oxide. The inclusion of protease enzymes provided improvements in final weight, weight gain and apparent feed conversion. The optimal levels of inclusion of exogenous protease in ration were 0.064 and 0.060% for weight gain and apparent feed conversion, respectively. The inclusion of protease did not provide differences in the apparent digestibility of crude protein and energy in the rations. It was concluded that the inclusion of 0.06% exogenous protease in the ration provides better performance for the Nile tilapia.