Trehalose as an Alternative of Egg Yolk in Ram Semen Extender

The aim of this study was to investigate the influence of replacing egg yolk with trehalose in Tris-citric-yolk extender on post-thawing of Barki and Rahmani ram spermatozoa parameters namely, progressive motility, viability, abnormalities, membrane integrity, and acrosome integrity. Fifteen ejaculates from 3 rams presenting each breed were collected by using the artificial vagina. Accepted semen samples were pooled and kept under 37°C then were immediately distributed on extenders with replaced egg yolk levels of 5, 4, 3, 2, 1and 0 % by respective levels 0, 25, 50, 75, 100, and 125 mM of trehalose. After an equilibration period, cooled semen was aspirated into 0.5mL straws and were frozen and stored in the liquid nitrogen. After 24 h, straws were thawed in a 37°C water bath for the 60s. Results revealed no significant differences between the two studied breeds of ram for all post-thawing spermatozoa parameters. The extender containing 50 mM trehalose and 3% egg yolk gave the highest post-thawing sperm motility and membrane integrity (41.43% and 44.47 %), while the lowest values (34.29 % and 37.40 %) were obtained from the extender containing 125 mM trehalose and 0% EY and was highly significant in total sperm abnormalities. Post-thawing sperm viability and acrosome integrity were not significantly affected by substituting different levels of trehalose for egg yolk. In conclusion, reducing egg yolk dawn to 1 % versus using high concentrations of trehalose (up to 100 mM) did not affect sperm characteristics, but complete elimination of egg yolk from the extender reduced post-thawing characteristics.