The objective of this study was to evaluate, in purified diets, the effects of different levels of crude fiber on the apparent digestibility and gastrointestinal transit rate in Nile Tilapia. Five circular fishbowls (250 L) with a closed system of water filtering, replenishment and heat for feeding and five digestibility fishbowls with individual filtering replenishment and heat system were used. Thirty-two fishes, averaging initial weight of 30.65 ± 0.50 were used. A completely randomized design with five levels of crude fiber (2.5, 5.0, 7.5, 10.0, and 12.5%) and five replicates was used. It was concluded that increasing levels of crude fiber in purified diets significantly affect the apparent digestibility of dry matter, crude protein and ether extract. Levels up to 5.0% crude fiber did not reduce the apparent digestibility of dry matter and crude protein and levels up to 7.5% crude fiber did not reduce the apparent digestibility of ether extract of purified diet in Nile tilapia. However, the increase of dietary crude protein significantly reduce the gastrointestinal transit rate.
crude fiber; digestibility; fish feeding; Nile tilapia; transit rate
