Synchronization of Oestrus in Sheep by Intravaginal and Subcutaneous Application of Progestin Impregnated Sponges

Shelton ( 1964) has described the testing of a number of progestins in the search for one which meets the specifications laid down by the author (Robinson ( 1960) as being necessary for the practical control of ovulation in farm animals. He found one compound, namely 17a-acetoxy-9cr fluoro-1 lP-hydroxypregn-4-en 3, 20-dione (Searle, Chicago; Code No. SC-9880) which appeared to have all the characteristics of progesterone but which was 25 times more potent. Further, he obtained definite evidence that physiological quantities of some progestins may be absorbed through the vaginal wall, when topically applied. This paper is a preliminary report of the development of a method of utilizing SC-9880 and vaginal application for the practical control of the time of ovulation and oestrus in the cyclic ewe. Two experiments have been conducted, one in collaboration with Dr. N. W. Moore at the McCaughey Memorial Institute, Jerilderie, N.S.W., in March 1964 and the other with Dr. S. Salamon on a private property at Blanket Flat, via Crookwell, N.S.W., in April.