The Influence of High Environmental Temperature on the Oxygen Consumption of Mature Domestic Fowl ,

IT IS generally known that the thyroid gland alters its activity in response to changing environments. It is probable that seasonal changes are mediated by way of the anterior pituitary. High environmental temperature depresses the release of thyrotropin and therefore, the thyroid hormone output by the thyroid, and low temperature increases the output of the thyrotropin with the resulting high thyroid output (Ring, 1939; MacGregor and Loh, 1941; Wolf and Greep, 1937). Winchester (1940) determined the thyrotrophic content of hen’s pituitaries and found the highest thyrotrophic hormone content during the month of February with a decreased content later in the season. It has been established, that low environmental temperature stimulates thryoid activity. Ring (1939) showed that low temperature increases the metabolic rate. Dempsey and Atwood (1943) found that the thyroid gland of rats produced more thyroid hormone when kept in a cold environment than when held at higher environmental temperatures…