Hematological parameters for male nile tilapia fed different oil sources

Abstract

Tilapia is one of the most bred species in Brazil because it is resistant to viral, bacterial and parasitic diseases when compared to other cultivated fish. Knowledge about the blood components and their function is important for normal and pathological balance. Different oil sources used to feed breeding males of Nile tilapia (Oreochromis niloticus) were evaluated on the hematological parameters. In the experiment, we used 80 male tilapias, 20 males for each treatment. The experiment was a completely randomized design with 4 treatments and four repetitions, which used a 32% CP diet and isoproteic isoenergetic 3,300 kcal DE kg-1 each implemented with a different oil source T1: linseed oil (OL), T2: soy oil (SO), T3: fish oil (OF) and T4: corn oil (CO).The feeding management consisted on two daily feeding at 8 am and 4 pm, in the amount of 3% body weight. The diet intake was 232.2 g/day. No significant difference was detected for the percentage of red cells, mean corpuscular volume, hematocrit, and mean leukocyte percentage. However, for the mean corpuscular hemoglobin concentration (CHCM) and hemoglobin, fish fed soybean oil presented significantly higher values than other treatments. The soybean oil, characterized by iron with a high bioavailability, led to higher levels of hemoglobin and CHCM in Nile tilapia, which possibly can reflect a greater oxygenation in fish. However, the fish oil originated greater values of both components of the blood (hematocrit, red cells) and immune (thrombocytes, monocytes, neutrophils and lymphocytes) system.