Avaliação econômica e de desempenho de duas linhagens de tilápia-do-Nilo (Oreochromis niloticus), alimentadas com duas rações comerciais, criadas em gaiolas no Rio Iguaçu – Reservatório de Salto Caxias

Abstract

This work aimed to evaluate the performance, the chemical composition of the whole body, intestinal integrity and economic viability of two strains (GIFT and Supreme) of Nile tilapia (Oreochromis niloticus) fed two commercial diets. The experiment was conducted in the reservoir of the Salto Caxias plant in the Iguaçu River, with three replicates in 4 treatments. 8500 fish were housed in each cage of 18 m³, a total of 12, in November 2014. The fishes of Supreme® and GIFT strains had initial weight of 1.27 g and 2.72 g, respectively. At 50,101 and 147 days were carried out classification and fish biometrics. For performance evaluation were calculated weight gain (WG), specific growth rate (SGR) and feed conversion (FC). At the end of the experiment intestine samples were collected and analyzed their integrity in scanning electron microscopy. Throughout 147 days were recorded expenses and income related to production for further economic evaluation. Regarding the GP there was only significant difference between the fish that received the initial diet microextrudada and prebiotics.. The SGR was higher for fish SUPREME strain in the two diets. The growth curve between the strains, it was observed that the curves maintained the same pattern with no marked differences between them, but with greater weight gain for the fish of the GIFT strain. The assessment of body composition of whole fish, held on 40, 70 and 116 days, the fish did not differ for dry matter content, but there was difference for crude protein at 40 days, ether extract and mineral matter 70 days between the fish that received the initial microextruded diet with prebiotics. Among the fish that received the initial mash diet without prebiotics, there was significant difference in crude protein, ether extract and mineral content at 116 days and the ether extract also differed at 70 days. In ultrastructural analysis of the fish intestine that received the initial microextruded feed with prebiotics was observed better tissue integrity of the intestinal mucosa, however, the treatments with use of initial mash diet without prebiotics lesions were observed in the mucosa and the presence of large number of attached microorganisms to mucosa. In the economic assessment was no difference in costs and revenues.Fish of the GIFT strain fed microextrudada diet additives, showed higher profitability, higher net present value (NPV) and higher internal rate of return (IRR). Excelling in higher growth and better economic performance, it was concluded that the GIFT strain, caged in the Iguaçu River, was better about GenoMar Supreme strain on both diets studied.