The Effect of Heat Exposure and Bacterial Endotoxin on Plasma Zinc Concentration and the Body Temperature in the Broiler

Abstract

The effect of heat exposure and bacterial endotoxins on plasma zinc levels and mean rectal temperature of 8 week old broilers were investigated. Broilers exposed for 2 hours to 35–37°C. had higher (P < 0.01) mean rectal temperatures (42.8 vs. 41.7°C.) than sham treated broilers maintained at 22–24°C. Likewise, endotoxin (E. coli, 500 μg./kg.) treated broilers also had mean rectal temperatures significantly higher (P < 0.01, 42.4 vs. 41.7°C.) than sham treated broilers. Plasma zinc levels in the bacterial endotoxin treated broilers were lower (P < 0.05) than in the sham treated (173 vs. 220, and 219 μg./100 ml. plasma, respectively). In contrast, the plasma zinc concentration was not significantly depressed in the broilers exposed to heat for 2 hours. In summary, either endotoxin or heat exposure resulted in increased body temperature, however only the response to endotoxin resulted in a significant depression of plasma zinc concentration.