General Appearance, Growth and Reproduction of Thyroidectomized Bovine

Abstract

A study of 6 thyroidectomized animals of various ages re-vealed general appearance and behavior effects similar to that observed for other species of mammals. Growth as measured by height at the withers became static although there were weight increases. Physiological estrus and libido in the [male] were absent although fertile ova and sperm were produced, as evidenced by birth of 3 normal calves from parents with marked myxodema. Normal breeding behavior in both sexes was restored by thyroid therapy. Growth was restored in late pregnancy due, presumably, to the fetal production of thyroxine. Incomplete thyroidectomy failed to produce any of the symptoms of hypothyroidism in either the mature or immature bovine.