SODIUM AND POTASSIUM-CHLORIDE DRINKING-WATER SUPPLEMENTATION EFFECTS ON ACID-BASE-BALANCE AND PLASMA-CORTICOSTERONE IN BROILERS REARED IN THERMONEUTRAL AND HEAT-DISTRESSED ENVIRONMENTS

One experiment utilizing 188 Vantress x Arbor Acres broilers was conducted to evaluate the effects of isomolar KCl (.5%) and NaCl (.39%) drinking water supplementation on venous pH, PO2, PCO2, HCO3-, hematocrit, and plasma corticosterone as well as rectal temperature and water consumption of broilers reared in heat-distressed and thermoneutral environments. Birds were allotted at 5 wk posthatch into either a thermoneutral (TN; 24 C) or cycling temperature (24 to 35 C) environmental chamber. Heat-distressed (HD) controls had elevated (P < .05) body temperature (42.9 versus 41.7 C) and PO2 (144.5 versus 108.4 mm Hg). Blood pH, PCO2, and HCO3- (P > .1) were not affected by high ambient temperature, but hematocrit (31 versus 32%) for HD controls was reduced (P = .07) compared with TN control birds. At 35 C, drinking water NaCl supplementation decreased (P < .05) venous PCO2 and HCO3-, increased (P < .05) PO2, and had no effect on venous pH and water consumption relative to HD controls. Potassium chloride lowered (P = .07) venous pH, decreased (P < .05) HCO3-, and increased water consumption at 35 C, but PO2 and PCO2 were unaffected relative to HD controls. Heat distress increased (P < .05) plasma corticosterone by 53%. Sodium chloride failed to impact (P > .1) plasma corticosterone but KCl reduced (P < .05) its concentration during heat distress and increased (P < .05) bird survivability as compared with heat-distressed controls. The data reported herein suggests that KCl and to a lesser extent NaCl reduces HD consequences by a mechanism as yet undefined.