Research note: 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 less than .05) body temperature (42.9 versus 41.7 C) and PO2 (144.5 versus 108.4 mm Hg). Blood pH, PCO2, and HCO3- (P greater than .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 less than .05) venous PCO2 and HCO3-, increased (P less than .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 less than .05) HCO3-, and increased water consumption at 35 C, but PO2 and PCO2 were unaffected relative to HD controls. Heat distress increased (P less than .05) plasma corticosterone by 53%. Sodium chloride failed to impact (P greater than .1) plasma corticosterone but KCl reduced (P less than .05) its concentration during heat distress and increased (P less than .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.