The objective of this research was to evaluate the effects of different crude fiber and soybean oil levels in diets for Tilapia Nile. Twenty-four circular fishbowls of 250 liters, with an individual system of water replenishment and heating, were used. The stocking rate was of seven fishes/fishbowl, totalizing 168 fishes, with average initial weight of 6.41±0.05 g. Weight gain, apparent feed:gain ratio, specific growing rate and protein efficiency rate were evaluated. The chemical composition and carcass yield, eviscerated carcass and hepatossomatic index were also studied. A completely randomized design was used, in a 3 x 2 factorial scheme, being three crude fiber levels (6.00, 9.00%, and 12.00%), and two soybean oil levels (0.0 and 10.0%), with four replicates. It was verified that it is possible to use, in the diet, levels up to 12.00% of crude fiber and its excess tends to decrease the weight gain and the protein efficiency rate, besides worsening the feed:gain ratio; the fiber significantly affect the dietary apparent digestibility, with positive and negative effect on the protein and dry matter digestibility, respectively, and without effect on the ether extract digestibility; the crude fiber did not significantly affect the carcass yield and the eviscerated fat deposition. However, the oil addition to the diet showed significant effect on the eviscerated fat deposition; the fiber resulted in significant effect on the carcass chemical composition of the carcass (water and protein contents), without effect on the fat composition; and the fat addition to the diet significantly decreased and increased, respectively, the carcass protein and ether extract contents. It was concluded that, in the growing phase (from 6.40 to 31.00 g), the dietary crude fiber levels up to 9.00% can be fed for Nile tilapia and the supplementation of high dietary lipid levels decrease the carcass composition and result in higher eviscerated fat deposition.
crude fiber; digestibility; fish nutrition; tailandesa lineage; oil
