The Effects Of 37℃ Constant Heat-stress On The Hemodynamics And Acid-base Balance In Broiler Chickens

The purpose of the experiment was to study the effects of constant heat-stress on the hemodynamics and acid-base balance in broiler chickens.1. The effects of 37℃ constant heat-stress on the hemodynamics in broiler chickensIn the period of 37℃ 12 days constant heat-stress, the femoral artery systolic/diastolic pressure, the maximum increasing rate of femoral artery (眃p/dt max), the pulmonary artery systolic/diastolic pressure, the right ventricular systolic/diastolic pressure, the maximum increasing rate of right ventricular (RV眃p/dt max), the production performance, and etc. of broiler chickens in different groups were examined continuously. The mean femoral artery pressure (mFAP, 16.97+0.41, 11.03+1.98 kPa) of the birds in the treated group decreased significantly (P <0.01), but there was an uptrend between 7~9 days after thermostress. The maximum increasing rate of femoral artery systolic pressure (+dp/dt max) decreased significantly (P <0.01) in the prophase, but increased significantly in the metaphase (P <0.05) and anaphase (P<0.01); The maximum increasing rate of femoral artery diastolic pressure ( | -dp/dtmax | ) decreased significantly (P<0.05) in the prophase, but increased significantly in the anaphase (P<0.05). The mean pulmonary artery pressure (mPAP) decreased significantly (P<0.01) at 1,5,7 and 12 days after thermostress, and decreased significantly (P <0. OS) at 3 days after thermostress. The right ventricular systolic pressure decreased significantly in the prophase (P<0.01) and metaphase (P<0.05), but increased significantly (P<0.01) at 9 days after thermostress. The right ventricular diastolic pressure decreased significantly (P<0.01) in the anaphase. During the experiment, the RV I 眃p/dtmax I decreased significantly (P<0.01). Body weight gain and feed intake of thermostressed chickens were decreased significantly (P<0.01), and feed/gain was increased significantly (P<0.01); The respiration rate and rectal temperature of heat-stressed broiler chickens were increased significantly (P <0.01) at 1, 5,7,9 and 12 days after thermostress. The mFAP had a significantly negative correlation with respiration rate and rectal temperature (r=-0.667, r=-0.644; P<0.01) ; The mPAP had a significantly negative correlation with mFAP, respiration rate and rectal temperature (P<0.01). These results showed that there are significant hemodynamics disturbance, severely affected physiological function and decreased production performance in the broiler chickens under 37℃ constant heat-stress. The change of FAP is close to the response and adaptation of chickens to thermostress.2. The effects of 37℃ constant heat-stress on the blood gas and acid-base balance in broiler chickensIn the period of 37℃ 12 days constant heat-stress, the blood gas, respiration rate, rectal temperature and production performance of broiler chickens in different groups were examined continuously. Twenty-four hours after thermostress there was a compensated respiratory alkalosis, which was characterized by the decreased partial pressure of CO2 (PaCO2, 3.82+0.36) and the increasedpH (7.48+0.04) in artery. Seven days after thermostress there was a decompensated metabolic acidosis, which was characterized by the dropped arterial blood bicarbonate ion (HCO3-1, 19.00+2.55) and the decreased pH value (7.37+0.06,P <0.05). Twelve days after thermostress acid-base balance was almost resumed. The oxygen partial pressure (PaO2) had a significantly negative correlation with respiration rate (P<0.01) and rectal temperature (P<0.05); The arterial blood oxygen saturation (SaO2) had a significantly negative correlation with rectal temperature (P<0.01). These results showed that there are a significant acid-base balance disturbance, severely affected physiological function and decreased production performance in the broiler chickens under 37℃ constant heat-stress.3. The effects of 37℃ constant heat-stress on the tectology in broiler chickensIn the period of 37℃ 12 days constant heat-stress, the dynamic change of tectolog...