Hormonal control of reproduction in sheep

Abstract

In summer 1973, the sheep farmer in most parts of the Irish Republic could telephone his local cattle Artificial Insemination (AI) station and ask for a technician to treat his ewes for ‘early-lamb’ (December/January) production with intravaginal sponges and pregnant mare's serum gonadotrophin (PMSG). The 60 p per ewe service, which first became available at that time, covered two visits by the technician: the first to insert sponges; the second, 14 days later, to withdraw them and administer the gonadotrophin. On the basis of considerable experimental evidence, the farmer could expect about 60 to 70% of ewes treated to conceive to first services and lamb within a short period of each other, and some 80% to produce offspring to the combined first and second services. The scheme, based on natural service, was used by several hundred farmers in that first year of operation, and was made available on a similar basis again in 1974. The introduction of this cheap, effective and simple technique for the hormonal control of reproduction in sheep was the result of considerable activity over the years by Dr Sean Crowley and his staff in An Foras Taluntais and various workers in University College, Dublin (UCD). Due credit must be given, however, to the Irish Department of Agriculture, which sponsored extensive field testing of controlled breeding techniques in 197/172, and subsequently arranged with cattle AI stations to provide countrywide coverage on a fee per ewe basis from 1973.