The Effect of Various Levels of Egg Yolk on Quality of Zel Ram Spermatozoa in Cooling and Freezing Conditions

The objective of this study was to investigate the effect of different levels of egg yolk on quality of Zel ram spermatozoa in pre and post freezing conditions. Semen samples were collected from 4 healthy and mature rams using an electro-ejaculator and suitable samples were mixed with Tris extender in a ratio of 1:4 semen and samples were assessed, after cooled to 5-0C. Then, 0.5 ml of straws were filled with diluted semen. At first, straws were frozen on liquid nitrogen vapor, then kept in liquid nitrogen and after 10 days straws were thawed to investigation of morphological characteristics, viability, motility and progressive motility of spermatozoa. This experiment was carried out on the basis of completely randomized design with 3 treatments include levels of egg yolk 10, 15 and 20% and 9 replications. Results showed that the effect of egg yolk on viability, motility, progressive motility, normal spermatozoa and recovery percentage of spermatozoa were not significant (P>0.05), but the higher quality of spermatozoa and supply of energy source given in 20% egg yolk for lifespan, despite the absence of significant, if price of egg yolk is economical, 20% egg yolk can be used in Tris extender for maintaining and long term storage of Zel ram spermatozoa.