Ewe Estrual Control: Are Vaginal Pessaries the Answer?
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Date
1968
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Publisher
North Dakota State University
Abstract
Description
Several 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.