Effect of egg yolk of four avian species on the cryopreserved ram spermatozoa

Egg yolk is the most commonly used cryoprotective agent for sperm cryopreservation of several species.The objective of this experiment was to compare the effectiveness of egg yolk from four avian species(domestic chicken, duck, turkey and pigeon) on sperm quality following cryopreservation of the ram semen.Ejaculates were collected, using an electroejaculator, from six fertile rams. Samples were diluted in a triscitricacid-fructose extender containing egg yolk (15%) and glycerol (5%). Diluted samples were cooledslowly to 5°C over 2 h and equilibrated at that temperature for 2 h. Aliquots of samples were loaded into 0.5ml straws and frozen in liquid nitrogen vapor for 15 min and stored in liquid nitrogen. Post-thaw progressivemotility, live/dead ratio and acrosomal integrity of 200 sperm per slide stained with eosin-nigrosin andgiemsa, were evaluated at 0, 2 and 4 h after thawing. Pigeon egg yolk had the most cryoprotective effect interms of progressive motility, livability and acrosomal integrity (P(Pindicated that pigeon egg yolk might be superior to chicken egg yolk for cryopreservation of ram spermatozoa in tris-citric acid-fructose yolk extender, however, further experiments are needed to evaluate its effects on fertility.