title: Involvement of the thyroid gland in the response of young chickens to heat stress.
abstract: The involvement of the thyroid gland in the response of young chickens to heat stress was studied. Mean survival times when exposed to 50 C were significantly shorter for 3-week-old broiler male chickens injected with 40 micrograms L-thyroxine (T4)/100 g body weight compared to chickens injected with 30, 20, or 0 microgram of T4/100 g body weight. A significant reduction in heat stress survival time was obtained when T4 was injected 12, 18, or 24 hr before heat stress but not 6 hr before. Triiodothyronine (T3) reduced heat stress survival time when administered 12 to 24 hr before the stress but not when given 6 hr before. Chickens made hypothyroid by radiothyroidectomy had significantly longer heat stress survival times than controls. Likewise, chickens fed a diet containing .2% thiouracil 10 days before heat stress at 28 days had significantly longer survival times than control birds.
mesh_terms: D000818:Animals; D001835:Body Weight; D002645:Chickens; D006358:Hot Temperature; D008297:Male; D011201:Poultry Diseases / Q000401:mortality / Q000503:physiopathology*; D013312:Stress, Physiological / Q000401:mortality / Q000503:physiopathology / Q000662:veterinary*; D013889:Thiouracil / Q000008:administration & dosage; D013961:Thyroid Gland / Q000502:physiology*; D013974:Thyroxine / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: D014284:Triiodothyronine; D013889:Thiouracil; D013974:Thyroxine