Restrição alimentar programada na produção de Tilápia (Oreochromis niloticus) em viveiros e em recirculação de água

Abstract

The development of more appropriate feeding programs as the intensity and duration of the restriction may constitute an effective way to minimize the effects of excessive consumption of food and its negative consequences for fish feeding efficiency and economy of business. Accordingly, the juvenile Nile tilapias (100 ± 2 g; 137 ± 3 g) were submetted to different feeding strategies in two different production systems, a semi-intensive in ponds and the other intensive, in recirculating water . In semi-intensive system with green water, four feeding strategies in subsequent weekly cycles were tested: VT1 - continuous feed; VT2 - one day of restriction a week; VT3 - two consecutive days of the restriction a week VT4 - three consecutive days of the restriction a week. In the intensive system with clear water were tested five feeding strategies in subsequent weekly cycles: CT1 - continuous feed; CT2 - deletion of one meal a week; CT3 - deletion of two non-consecutive meals a week; CT4 - deletion of three non-consecutive meals a week; CT5 - deletion of four non-consecutive meals a week. We evaluated the growth performance, feed intake in the post-restriction period, the yield of commercial cuts, the chemical composition and water activity in the carcass, the indices of digestive organs, bowel histology, energy metabolism and intermediate economic indicators by means of projections and profitability analyzes. Compensatory intake occurred in both assays, with an increase around 20 % in the first feeding throughout the experimental period. In the trial in nurseries, the control group weight gain was higher compared to groups subjected to restrictive management, while in the test recirculation system there were no significant differences. Feed conversion of groups in ponds was not significantly different. The quality of carcass and industrial yield did not differ significantly in both assays. Somatic index, organs morphometry and intestinal villi height did not differ statistically among the tested groups. The intermediate energy metabolism indicated that there was no intensive use and/or lasting plasma energy stocks, showing the ability of Nile tilapia to maintain stable glucose levels, triglycerides, cholesterol and total protein under restriction in days in semi-intensive system. In semi-intensive production systems there was rationalization of feed and labor, which promoted overcoming of the economic efficiency of the tested groups compared to the control group. Restrictive feeding strategies applied to intensive production system allowed to optimize the labor and improve the economic efficiency of business compared to those without food restriction. The restrictive feeding management configured in the form of consecutive days and meals, as used in these studies to semi-intensive systems and intensive, respectively, can be recommended as a management strategy in tilapia production. Considering the change in fish prices and the increase in the purchase price of inputs such as food and labor, the projections and sensitivity analyzes attested gain in competitiveness of fish farms in pond and recirculation systems of different sizes,. When the trial involves reduction and/or optimization of inputs for the production of commercial fish, the growth performance in itself, may not be able to point if technologies or management methods used make the activity more profitable. Economic analyzes based on actual food cost and operational efficiency are essential to managing for results in aquaculture.