Hematology of Nile tilapia fed diets with vegetable oils and stimulated by cold

Abstract

The objective of this work was to evaluate the effect of diets with different omega-6 and omega-3 polyunsaturated fatty acid ratios on the hematological parameters and plasma lipids of Nile tilapia before and after cold stress. A total of 320 tilapia juveniles sex-inverted males (±7.50 g) were randomly distributed into 40 tanks (250 L) and feed with eight diets: basal (without oil supplementation), 6% sunflower oil (SO), 5% SO + 1% linseed oil (LO), 4% SO + 2% LO, 3% SO + 3% LO, 2% SO + 4% LO, 1% SO + 5% LO, and 6% LO. Hematological parameters and plasma lipids were evaluated 85 days after cultivation and three days after cold stress. Diets had no effect on any of the analyzed variables before cold stress. The number of leukocytes decreased in fish fed the 6% LO diet, after cold stress. Cold stress worsened fish health, causing leukopoenia. Nile tilapia fed 6% LO diet presented less resistance to cold.