Effect of excess sodium bicarbonate on the blood volume and erythrocyte deformability of broiler chickens.

Broiler chickens were treated with 7.5% of sodium bicarbonate in their drinking water from 7 to 29 days of age to test the hypothesis that excess dietary sodium bicarbonate increases blood volume and decreases erythrocyte deformability thus contributing to the development of pulmonary hypertension-induced right ventricular failure and ascites. Sodium bicarbonate treatment resulted in 16% mortality from ascites compared to 2% mortality from sudden death syndrome in control broilers. Blood volume was increased significantly at post-treatment days 1 (16%) and 3 (11%) and was higher in treated broilers for the remainder of the experiment. Erythrocyte deformability was significantly decreased at post-treatment days 2 (16%) and 4 (33%). Erythrocyte number, haemoglobin and haematocrit were lower at post-treatment days 1 and 2. After this time, these values were higher than in control broilers. Serum Na+ concentration was significantly higher at post-treatment days 2 and 4. Right ventricle to total ventricular weight (an indication of pulmonary hypertension) was increased significantly at post-treatment days 1, 2, 21 and 22. These results indicate that reduction of erythrocyte deformability and increased blood volume may contribute to the development of pulmonary hypertension-induced right ventricular failure and ascites in sodium bicarbonate-treated birds.