effects of frozen diluents on storage of ram sperm

semen collection evaluation and addition of preservatives to increase storage period of sperm are essential for successful artificial insemination. this study was conducted on 4rams (2 ghezel merinos and 2 merinos moghani) to evaluate the effect of two diluents in khalatposhan research station. average age of rams was 3 years. rams were trained to serve the artificial insemination and semen samples were collected weekly. it was started from october 2011 to june 2012. after collection semen samples were mixed with diluents. they were stored in liquid nitrogen. after diluting and storage semen was assessed after 0, 1, 2 and 3 day for ph, viability and progressive motility. frozen straws were thawed individually at 37 °c for 20 s in a water bath for evaluation. effect of diluent and storage day on ph, viability and progressive motility of sperm were significant (p< 0.01). with the increasing storage day ph, viability and progressive motility of sperm decreased. the success of these diluent has been attributed the tris which may act as a buffer against changes in ph and tonicity. fructose and citric acid are energy source. egg- yolks protect the cell membrane during cooling. glycerol protects the spermatozoa against membrane damage during freezing. this study showed that diluents containing of 7% glycerol and 20% egg-yolk had better sperm protection ability than extender containing 5% glycerol and 5% egg-yolk  according to sperm motility, ph and sperm viability