Body Temperature and Blood Chemistry Responses in Broiler Cockerels Given a Single Intravenous Injection of Na+ or Ca++ Before an Acute Heating Episode

Abstract

Eight-week-old broiler cockerels were injected intravenously with avian saline containing additional Na+ as Na Cl or Ca++ as CaC12. After the injections half of the chickens were heated at 45° C. and the others were maintained at 24° C. Cloacal body temperatures were determined and blood samples were collected before heat exposure and at 30 minute intervals until the chickens had been heated for 120 minutes.Na+ did not affect body temperature of chickens in the 24° C. environment, but Na+-treated chickens in the 45° C. environment had significantly elevated body temperatures compared to the heated controls. Ca++ caused a significant decrease in body temperature of the non-heated chickens, but it was without effect in heated chickens. Neither Na+ nor Ca++ altered the responses of plasma glucose, cholesterol, and calcium during the heating episode. However, Ca++ caused a significant rise in plasma inorganic phosphate in non-heated chickens and prevented the rapid decline in the heated chickens. Na+ caused a significant fall in plasma inorganic phosphate in non-heated chickens, but it did not alter the plasma phosphate response to acute heat stress. The present experimental results suggest that Ca++ but not Na+ injection influences body temperature regulation in chickens in a moderate temperature environment, and suggests that Ca++ initially exerts a peripheral rather than a central effect in decreasing the body temperature.