Hematological parameters of Nile Tilapia (Oreochromis niloticus L.) under air exposure stress

Silva R. D., Rocha L.O., Fortes B. A. D., Vieira D. & Fioravanti M. C. S. 2012. [Hematological parameters of Nile Tilapia (Oreochromis niloticus L.) under air exposure stress.] Par metros hematologicos da tilapia-do-Nilo (Oreochromis niloticus L.) sob estresse por exposicao ao ar. Pesquisa Veterinaria Brasileira 32(Supl.1):99-107. Setor de Patologia, Escola de Veterinaria e Zootecnia, Universidade Federal de Goias, Campus Samambaia, Cx. Postal 131, Goiania, GO 74001-970, Brazil. E-mail: diasroberta5@gmail.com The present study evaluated the hematological and biochemical parameters of adult tilapia (Oreochromis niloticus) under the influence of the physiological stress factor in animals submitted to air exposure during fattening in raceway system. Blood cell count, hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), leukogram, differencial leukocyte count, platelet, glucose, total protein, cholesterol, triglycerides and electrolytes (calcium, chloride, sodium and potassium) were analyzed. The results showed a uniform distribution for red blood cells, hematocrit, hemoglobin, secondary Wintrobe indices, total protein, glucose, cholesterol, and serum ions, indicated by a relatively low variation coefficient. There was positive correlation only for total white blood cells, organic defense cells (neutrophils and lymphocytes), glucose, cholesterol, sodium and calcium. As for the leukocytes (WBC), as the animals were exposed to aeration, the number of leukocytes gradually decreased (leukopenia), simultaneously occurring neutrophilia and lymphopenia. The glycemic index was a good indicator of physiological stress due to hyperglycemia (82.0 +/- 20.88mg/dL) demonstrated in the treatments. The air exposure constituted an imbalance factor at the ion homeostasis and at the endogenous cholesterol synthesis. Besides, the recovery time did not result in the complete physiological rehabilitation face the imposed challenge.