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It is possible to collect and successfully cryopreserve ejaculates in a non-mating season from rams of the autochthonous breeds Karakachan, Cooper-red Shumen and Karnobat-local, raised in Bulgaria. Studies are in progress aiming the elaboration of optimal cryoprotective extenders and freezing technology.

The aim of the present study is to induce the sexual activity and to attain ejaculation during non-mating season in aboriginal ram breeds bred in Bulgaria. The possibility is discussed to use these rams with regard to the selection activity in effective sexual way.

The present study was conducted to detect sperm apoptosis in fresh, capacitated and frozen ram semen and to determine its relationship with other seminal parameters as motility and viability. The cryopreservation process induces the plasma membrane disruptions, attended with increasing of phoshpatidylserine molecules expression on the extracellular surface, wherefore some of the live spermatozoa loss their biological potential to fertilize the egg.

In vitro induced apoptosis by dexamethazone treating of ram spermatozoa provoked the phospatidylserine exposure which is mainly localized on sperm tail region of plasma membrane and is correlated negatively with the sperm motility and survival rate.