Objectives: This study was designed to examine the effects of various concentrations of tris (hydroxymethyl) aminomethane (tris) and egg yolk on the quality of cryopreserved buck sperm. Materials and Methods: The collected semen samples were pooled, washed, and diluted into five different freezing extender groups, viz., extender I (tris 0% + egg yolk 0%), extender II (tris 1.41% + egg yolk 4%), extender III (tris 2.41% + egg yolk 8%), extender IV (tris 3.41% + egg yolk 16%), and extender V (tris 4.41% + egg yolk 24%). The sperm parameter of the five groups of extenders was evaluated after equilibration and cryopreservation. Results: The results showed that extenders II–V provided significantly higher semen progressive motility and total motility percentages than extender I after equilibration (p < 0.05). The higher percentages of semen progressive motility, total motility, viability, and plasma membrane integ¬rity (by both HOST under light microscopy and stain after HOST under light microscopy) were found in the sperm cryopreserved with extender IV than extender I, extender II, and extender III groups after thawing (p < 0.05). In addition, semen progressive motility, total motility, and viability were not further increased, or plasma membrane integrity (by both HOST tests) was decreased by the addition of tris and egg yolk (extender V) after cryopreservation (p < 0.05). Conclusion: In conclusion, our result indicates that the following washing, the supplementation of tris (3.41% + egg yolk 16%) on the freezing extender are suitable for improving the semen quality of buck after freezing and thawing. [J Adv Vet Anim Res 2022; 9(4.000): 676-683]

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.