The Use of Progestagen Sc 9880 as an AId for Artificial Insemination in Ewes

We have analysed the most favorable conditions for obtaining good fertility, prolificity and fecundity in non-lactating ewes treated with hormones (vaginally administered fluorogestone acetate and PMSG) and inseminated with either fresh ( I5 °C) or frozen (― 19 6 0 C) semen, without prior detection of oestrus.This study has shown that even during the breeding season, PMSG should be associated with progestagen, and that the results also depend on the quantity of hormone contained in the vaginal sponge.The technique of semen preparation and administration (quality of diluent, timing and number of inseminations, final semen concentration) is an equally important source of variation.The results presented indicate that the technique of synchronisation of oestrus with hormones associated with artificial insemination (fresh semen : i AI/female ; frozen semen : 2 AI/female) can be used throughout the year, but we find slightly better results with fresh semen than with frozen semen.--!._--It is now well-known that the use of progestagens to control estrus and ovula- tion in sheep cannot be dissociated from artificial insemination.More advantages may be obtained from estrus synchronization with AI than with natural service.Unfortunately, the decline in fertility which appears following the application of a progestagen treatment is more marked with artificial insemination than with mating (I,i ND Sn Y et al., i 9 6 7 ; WiL L EMSE, BRAND and MU RL I N G, 19 68), and the reasons for this phenomenon are not clearly elucidated.The purpose of this paper is to review the three most important factors involved in the success of both oestrus synchronization and AI.Their effects have been stu- died on reproductive performances (fertility, prolificacy, fecundity) of nonsuckling ewes, artificially inseminated with liquid and deep-frozen semen.