Caracterização de variedades de tilápias nilóticas alimentadas com diferentes óleos

Abstract

Nile tilapia (Oreochromis niloticus) is one of the most commercially cultivated species in the world, being preferred for its high rusticity and adaptability, fast growth and meat with desirable characteristics. Traditionally, fish oil is used as a lipid source in the diet of several aquaculture species. Due to the high costs and scarcity of fish oil, alternative sources that do not compromise the performance, health and quality of fish are needed, one of these alternatives being vegetable oils. In this context, the general objective of this project was to evaluate the influence of different sources of dietary oils in four varieties of Nile tilapia on performance, fillet quality, blood biochemical parameters and interaction between oil sources and varieties. Also, varieties were characterized regarding morphometric characteristics, yields, fillet quality and nutritional indexes of lipid quality. In the characterization step, 40 male specimens of Nile tilapia were sampled, 10 of each variety. In the next step, 192 males of Nile tilapia were used in the finishing phase, with 48 animals of each variety. The fish were distributed in 16 polyethylene boxes of 500 L, each containing three animals of each variety, totaling 12 animals per box. The experimental design was carried out in randomized blocks, in split plots, using four diets: commercial feed; fish oil; corn oil and linseed oil and four varieties: red UFLA, Genetic Group I, UFLA and Genetic Group II, with four replications, with fish as the experimental unit. The diets were semi-purified (isoprotein and isoenergetic), and the supply period was counted in days before slaughter (60 days). As for the characterization of the varieties, the results indicated that there are differences between the Nile tilapia varieties in terms of body shape, body yield, pH and water activity. Among the varieties, UFLA presented desirable conformation characteristics and higher fillet yield. However, the fillets of the Nile tilapia varieties evaluated in this study proved to be excellent sources of protein, with desirable fatty acids and nutritional indices of lipid quality, suggesting that the consumption of these varieties can be considered beneficial to human health. As for the influence of oil sources, the diets did not influence (P<0.05) the chemical and physicochemical composition of fillets, blood biochemical parameters and animal performance. However, differences were observed between varieties (P <0.05) for moisture, lipids and light parameters. As for fillet performance and yield, there was a difference between varieties (P < 0.05). In the blood biochemical parameters there was difference (P<0.05) between the varieties for glucose and triglycerides. And globally, there were positive trends in meat quality, since it showed low levels of fat and cholesterol and satisfactory proximate composition for the species. Therefore, supplementation with different sources of vegetable oil is an option for the maintenance of physicochemical parameters of the meat of tilapia varieties, performance and biochemical parameters of blood.