effect of egg yolk and cooling on storage of ram coated spermatozoa

this study was conducted to evaluate the effect of egg yolk and cooling on ram coated spermatozoa. semen was collected from three ram by artificial vagina contacted with a tube containing tris- fructose-egg yolk 15%. samples were pooled, centrifuged by 700 g for 10 min and removed supernatant. then, samples were diluted by tris-glucose and centrifuged again to remove seminal plasma and egg yolk. aliquots split into two fractions and each one was split into 5 parts and added egg yolk 0, 5, 10, 15 and 20%. the half of the treatments were gradually cold and other ones were encountered with cold shock then samples were incubated at 5c for 72 h. progressive sperm motility, plasma membrane integrity, viability (by hoechst 33258 fluorescent staining) and acrosome reaction (by pna-alexa flur-488) were investigated at 0, 24, 48 and 72 h. the results showed that there was no difference between 15% and 20% egg yolk in the progressive sperm motility but they were higher than 0% and 5% egg yolk. there was highest difference between 0% and 20 % egg yolk in the progressive sperm motility. there was no difference among the treatments containing egg yolk in plasma membrane integrity and acrosome reaction. in both cooling rate, there was no difference among the treatments containing egg yolk in the sperm viability. it was suggested that 20% egg yolk was superior to keep the function of ram coated spermatozoa for storage at 5c.