عنوان مقاله [English]
Background and objectives: The storing and cryopreservation of livestock semen for long time cause using possible benefits of the best genetic reservoirs, but during cryopreservation, damages from peroxidation and cold shock lead to a lowered semen fertility. So, using compounds in semen extender effective on fertility is pivotal. In this study, three experiments were conducted to investigate effect of different soy lecithin instead of egg yolk in Tris extender and also adding bovine serum albumin on fertility traits of bovine semen stored under three thermal conditions; room temperature (24°C), chilling temperature (5°C), and frozen in liquid nitrogen. Materials and methods: semen samples were collected from four Holstein bulls (about 3 years old) using artificial vagina and pooled after initial quality evaluation. Semen samples then were extended by four different extenders containing egg yolk (20%) and three levels of soy lecithin (0.5, 1 and 1.5%). Before filling 0.5ml straws with extended semen, 10mg bovine serum albumin was added to the half of straws. Straws were stored at three thermal conditions; under room temperature and evaluation at hours 3, 6 and 9, under chilling temperature and evaluation at hours 3, 24 and 48, and under freezing condition and evaluation of thawed straws at days 5, 10 and 15 post-freezing. Sperm concentrations, viability and motility were evaluated microscopically. Data were analyzed as a 2×4×3 factorial experiment (including extender, bovine serum albumin and time effects) with a completely randomized design. Means comparison was by the least significant difference test. Results: Results from the experiment under room temperature showed that the effects of extender and time on sperm viability and motility were significant (p<0.01) but adding albumin had no significant effect on that. The highest sperm viability and motility percentages were 99.88 and 99.75 in egg yolk group at h 3, respectively. Regarding to the results from chilling condition, the effects of extender and time on sperm viability and motility were significant (p<0.01) but adding albumin showed no significant effect. The highest sperm viability and motility percentages were 98.34 and 97.67 in egg yolk group at h 3, respectively. The effects of extender and time on sperm viability and the effect of extender, albumin and time on sperm motility after thawing were significant (p<0.05). The highest sperm viability and motility percentages were 68.18 and 65.62 in egg yolk group at day 5 post-freezing, respectively. Conclusion: Generally, results of the study showed that in Tris semen extender, using egg yolk than soy lecithin has priority for storing bull semen in liquid and frozen conditions. Furthermore, adding bovine serum albumin into extender is not effective on bovine sperm viability and motility.