The aim of this study was to evaluate the hematic response of Nile tilapia (Oreochromis niloticus) fed diets supplemented with choline and submitted to temperature stress. The experimental period was realized in two phases: the first, during 109 days, and the second, for seven days. During the first stage, 192 fingerlings with average initial weight of 4 g were distributed in 32 net cages (200 L) allocated in 1,000-L aquaria. The diets were formulated to present 28% of digestible protein and 3,100 kcal DE/kg and the same concentration of amino acids. It was used a complete random experimental design with eight treatments and four replicates. The diets were choline supplemented (60% choline chloride) in order to present 100.0; 200.0; 400.0; 600.0; 800.0; 1,000.0 and 1,200.0 mg/kg of diet and evaluated by comparing to a non-supplemented diet. After the 109-day period, the hematological analyses of the fish were performed. After these analyzes, fish were transferred to the challenge room, distributed in 24 aquaria, and kept at 17ºC during seven days. After this period, the same analyzes of the period previous to the challenge were done. Choline supplementation did not affected erythropoiesis to stimulus by the cold temperature. Dietary choline supplementation does not affect erythrocyte and leukocyte synthesis and the 17ºC temperature determines lymphopenia and neutrophilia.
choline chloride; fish nutrition; hematology; stress; temperature
