The effect of different levels of raffinose and different extenders on characteristics of Dalagh ram semen after freezing and thawing

One of the pivotal technology for genetic resorviors preservation is the freezing of semen. As freezing causes a reduction in sperm fertility, adding some components to semen to preserve its ferility would be important. Since beginning the time of artificial insemination technique, different diluents have been used to preservation semen in liquid and frozen condition. Therefore, the goal of this stady was to investigate the effect of adding different levels of raffinose and milk, Tris-chicken egg yolk and Tris-soybean lecithin extenders on ovine semen characteristics after freezing and thawing.

Samples were collected from four mature Dalagh rams and extended by different extenders and then raffinose was added. Semen samples were aspirated into 0.5 ml straws and cooled to 4°C within 150 min and then frozen in liquid nitrogen Frozen straws were transferred to a tank containing liquid nitrogen. After thawing spermatozoa quality parameters including percentage of sperm motility, viability, membrane integrity and sperm normality were evaluated. This study was performed in a 4×3 factorial experiment with a completely randomized arrangement. Treatments were four levels of raffinose (0, 60, 70 and 80 mmol) and also three kinds of extenders (milk, tris-egg yolk and tris-soy lecithin). The obtained data from this study were analyzed by ANOVA procedure of Statistical Analysis System SAS (version 9.1). Comparison of data means were performed by Tukey test at the level of %1 error.

Results showed that adding raffinose had a significant effect on sperm viability and mobility (P<0.01), but did not significantly affect on sperm memberane integrity and normal morphology percentages. Effect of extender on percentages of motility, viability, membrane integrity and normal morphology of sperms was significant (P<0.01). The interaction between raffinose levels and extenders on percentages of motility, membrane integrity and normal morphology of sperms was significant while it was not for viability percentage. The greatest sperm mobility (35.00±2.09%) was in tris-egg yolk extender containing 60 mmol raffinose while that greatest sperm viabilty (74.40±1.88%) was in tris-egg yolk extender containing 80 mmol raffinose but also the most percentages of membrane integrity (66.40±2.60%) was in Tris-chicken egg yolk containing 0 mM raffinose. The greatest sperm normal morphology (74.80±2.82%) was observed in tris-soy lecithin extender containing 60 mmol raffinose.

Findings of the study showed that sperm characteristics including mobility and normal morphology percentages in level 60ml raffinose, membrane integrity percentages in level 0ml raffinose wihle for viability percentage were better preserved in 80ml level. In the other hand, tris-egg yolk extender had more prominant effect on preservation of sperm characteristics.