Effects of Corticotropin and Heat on Corticosteroid-Binding Capacity and Serum Corticosteroid in White Rock Chickens

The effects of the administration of corticotropin (ACTH) or high environmental temperature on serum maximum corticosteroid-binding capacity (MCBC) and serum corticosteroid concentrations were studied in 6- to 8-wk-old White Rock chickens. Highly significant increases in serum corticosteroids produced by either intramuscular or intravenous injections of ACTH were followed by significant reductions in MCBC within 24 hr. A single high-temperature episode (46 C) caused a significant increase in serum corticosteroids when blood was sampled immediately following exposure to heat; however, serum corticosteroids were not significantly increased following two heat episodes spaced 11 hr apart. Exposure to high temperature did not alter MCBC levels.