Restrição alimentar para tilápia do Nilo (Oreochromis niloticus)

Abstract

In order to assess different dietary restrictions for juvenile Nile tilapia (Oreochromis niloticus) which does not promote injury to the fish, was analyzed the following zootechnical parameters; the centesimal composition of whole fish and morphometry of muscle fibers and height of intestinal villi and the economic viability. Have been analyzed 160 fish (3.23 ± 0.07 g), over 20 nylon mesh net cages disposed in a concrete tank with central blower constant aeration system. The experimental methodology was completely randomized with four different treatments and five replications. Treatments consisted of 7: 0 - fed daily; 6: 1 - fed six straight days of a day of feed restriction; 5: 2 - fed five days followed by two days of feed restriction and 1: 1 - fed one day, followed a day of food restriction. It was used commercial feed with 33.70% crude protein, and the fish were fed four times a day to apparent satiation for 60 days. At the end of the experimental period significant differences were observed between the different dietary restrictions (P <0.05) for final weight, weight gain, final length, hepatossomatic index, visceral fat, intestinal quotient, specific growth rate, moisture, lipids, mineral matter and the rate of muscle fibers classes <20 µm and between 20 and 50 micrometers. The height of intestinal villi did not differ (P> 0.05) between treatments. The cost of food and partial net revenue were higher to those fed daily than the others. Therefore, it is concluded that dietary restriction for Nile tilapia in the juvenile stage may cause negative impact on growth performance, the chemical composition and muscle growth, making this practice indeed be uneconomical for commercial production.