Estrous Cycle and Ovulation Control in Cattle

Abstract

Basic concepts of anterior pituitary and hypothalamic control of ovarian functions and the estrous cycle in cattle were reviewed. New methods being developed for synchronizing estrous cycles in cattle were discussed in detail. Feeding Holstein heifers an orally active progestational agent, 6-Methyl-17-acetoxy-progesterone for 20 days at levels of 0.2 to 0.5 mg per pound of body weight has resulted in a large percentage of the treated animals being in estrus on the 3d and 4th days following cessation of treatment. Successful synchronization was also obtained in Holstein heifers after a 10-day treatment period involving progesterone feeding and uterine dilatation. Nearly normal conception rates were obtained in heifers bred at the controlled estrus in some of the trials but fertility of the treated animals was not adequately tested. The relationships of this newer knowledge of estrous cycle regulation to the problem of anestrus in cattle was discussed.