2010-05-052010-05-051968https://hdl.handle.net/10365/8984Several means were used to try to control sexual behavior in sheep. Success was varied. These methods included the use of injectable materials and oral administration of hormones and allowing limited exposure time to light. In some instances the amount of time spent applying techniques' of estrual control was not worthwhile. A technique new to 1968 for the administration of estrus suppressing hormones was developed. It involved the insertion of a sponge saturated with "Cronolone" into the vaginal region. The vaginal pessary was inserted with a plastic tube (speculum) and plunger apparatus. Insertion was a relatively simple operation, requiring only a few minutes per animal. It was concluded that by preventing ovulating hormone (LH) release the oral progestogens, the vaginal pessaries may have provided a satisfactory means of estrus synchronization. The pessaries effectively controlled the occurrence of estrus as evidenced by 87 8 % of the ewes coming in heat within six days after treatment. Estrogen production, which required ovulating hormone, was retarded until the pessary containing progestogen was removed.North Dakota State UniversitySheepLivestock productionArticle