Desempenho produtivo e morfologia de órgãos de tilápia do Nilo cultivadas sob diferentes estratégias alimentares com ciclos curtos de restrição alimentar

Abstract

Research related to aquaculture is of great importance in decision making within a production system, assisting in management, performance, feeding. Likewise, it is possible to observe a great behavioral variety of fish species produced in aquaculture. This research aims to evaluate the growth performance of juveniles of Nile tilapia (Oreochromis niloticus) according to different feeding strategies with food restriction. The experiment was carried out in two phases, the first being to assess the species' ability to learn by triggering the self-demand system. For this, 04 tanks with a capacity of 310L were used, with 10 animals each. In each of the tanks, an automatic feeder composed of an infrared sensor was installed to learn the animals to activate the system whenever they feel the need. In the second phase, 12 tanks of 310L were used, with 10 animals each, where different feeding methods were compared: Self-feeding with food restriction (4 days of food and 2 days of food restriction); Apparent satiety feeding with food restriction (4 days of food and 2 days of food restriction); Feeding by offering 2% of the biomass weight of the total of animals with feed restriction (4 days of feeding and 2 days of feeding restriction), making 3 treatments with three repetitions each. During the first experimental phase, the learning of tilapia in activating the photocell and, consequently, activating the automatic feeder was evaluated, so that the animals that constituted the self-demand strategy with restriction would occur (in this learning phase, no restriction was performed). Animals under the self-demand and apparent satiety feeding strategy with two-day food restriction had higher final weight and weight gain (P<0.05). For daily weight gain, self-demand and apparent satiety dietary strategies with food restriction showed greater daily weight gain (P<0.05). Higher total consumption, daily consumption, protein consumption and nitrogen consumption were found for the strategy of self-demand and apparent satiety with restriction that showed significant differences (P<0.05). For food efficiency, statistical differences were found (P<0.05), higher values for 2% of the biomass with restriction. Higher consumption by tanks was found for the self-demand strategies with restriction and apparent satiety with restriction (P<0.05). For specific growth rate at apparent satiety with restriction, it presented the best results and the 2% biomass feed strategy showed the lowest specific growth rate in the period of 60 days of experimentation. No statistical differences were found (P>0.05) for the viscerosomatic index (IVS), hepatosomatic index (IHS), gonadosomatic index (IGS), but for visceral fat index (IGV) there were statistical differences (P<0.05) because in the 2% strategy with restriction. The selfdemand and apparent satiety dietary strategies associated with food restriction can be applied in fish production, since the juvenile tilapia was able to achieve compensatory growth under a short period of food restriction.