The effect of controlled temperature variations on growth rate and blood pressure, hematocrit, and hemoglobin values in the turkey

Hypertensive and hypotensive strains of turkeys were observed for the possibility of a synergistic response between hypertension and temperature stress. The birds in four experiments were placed in chambers with temperature settings of 15.6, 26.7, and 37.8 C (humidity approximately 60%) and an ambient control. The temperature effect was measured by comparing the responses in body weight-gain, systolic blood pressure, and hematocrit and hemoglobin values. In each experiment both hypertensive and hypotensive strains in the 37.8 C chamber had a significantly lower (P less than or equal to .05) weight gain than those in the other chambers. The 26.7 C chamber had the next lowest weight gain. Considerably more variability in weight gain was observed in the hypertensive strain. Systolic blood pressure data were similar for all experiments. The lowest average blood pressures were recorded in the 37.8 C chamber. The high and low blood pressure strains showed overall average decreases in blood pressure of 28% and 14%, respectively. There was no consistent response in hematocrit and hemoglobin values due to temperature stress. Overall average hematocrit values were 39.1 and 38.0% for the hypertensive and hypotensive strains, respectively, while average hemoglobin values were 11.8 and 12.2 g/dl. The hypertensive strain showed more variation in weight gain, a greater percentage drop in blood pressure, and a 19% mortality rate in the high temperature chambers. These factors indicate that hypertension is an added factor in the overall stress of these birds.