Óleo de soja na nutrição da tilápia-no-Nilo (Oreochromis niloticus) na fase de terminação

Abstract

The aim of this study was to evaluate the inclusion of different levels of soybean oil on the animal performance, hematological condition and evaluation of chemical composition of Nile tilapia fillets fed with increasing levels of soybean oil diets. 270 tilapia with average initial weight of 425.33 ± 32,37g and initial length of 25.53 ± 2.00 cm were used, at completely randomized design in 15 tanks. Diets were formulated to present isonitrogenous (30%) using different addition levels of soybean oil, a total of five treatments (0.00; 1.50; 3.00; 4.50 and 6.00%) and three replications. The parameters of zootechnical performance evaluated were: survival (S), daily weight gain (DWG) and feed conversion rate (FCR). The body parameters evaluated were: carcass yield (CY), fillet yield (FY), dressed out yield (DOY), visceral fat index (VFI) and hepatosomatic index (HSI). For hematological and biochemical parameters the concentrations of total protein mg/dL (TP), total cholesterol mg/dL (TC); glucose (GL), triglycerides (TG), hemoglobin, erythrocytes and hematocrit were analyzed. For the proximate studies nine fillets from each of the experimental units were used, in which it was determined the moisture (M), crude protein (CP), ether extract (EE) and ash (A). In animal performance, there were no statistical difference (p <0.05) for the daily weight gain (DWG), with higher value 4,13g.dia-1 and feed conversion (FC) with the lowest value (1.87) observed when included 4.50% soybean oil in the diet. Polynomial effect for carcass yield was observed and the highest value (90.07%) occurred in 3.95% soybean oil. The lowest value of the visceral fat index (VFI) obtained was 3.85% and the estimated polynomial effect LRP with 4.86% soybean oil addition. For the hepatosomatic index variable polynomial effect was observed with lower value (2.14%) to 3.22% soybean oil addition. The variable total cholesterol showed quadratic effect with the lowest value (117 mg.dL-1) at 0.80% soybean oil inclusion. The variable triglycerides showed LRP effect with the highest value (269.35 mg.dL-1) observed at 5.04% inclusion. Distinctions (p <0.05) were observed in crude protein and ether extract values with reduction to crude protein and increase of the ether extract with LRP effect for these variables in the near concentration of 4.50% soybean inclusion. In conclusion, data showed that diets with levels between 2.00 and 4.50% soybean oil inclusion allows better carcass yield (CY), daily weight gain (DWG), lower levels of visceral fat Index (VFI) and hepatossomatic index (HSI), also a deposition of intramuscular fat with consequent reduction in protein content