Ethylene glycol, but not DMSO, could replace glycerol inclusion in soybean lecithin-based extenders in ram sperm cryopreservation

- Effects of glycerol, ethylene glycol or DMSO was evaluated in a soybean lecithin extender for freezing ram semen.
- No significant difference was found between glycerol and ethylene glycol at different concentrations (3% and 5%) regarding sperm motility, viability, and membranes integrity.
- Glycerol in a soybean lecithin based extender could be replaced by ethylene glycol, 3% or 5%.

The aim of this study was to evaluate the effects of glycerol, ethylene glycol or DMSO in a soybean lecithin extender for freezing ram semen. In this study, 20 ejaculates were collected from four Ghezel rams and diluted with soybean lecithin extender with glycerol (7%), ethylene glycol (3%, 5% and 7%) or DMSO (3%, 5% and 7%). Sperm motility (CASA), membrane integrity (HOS test), viability, total abnormality, mitochondrial activity (Rhodamine 123) and apoptotic features (Annexin V/Propidium iodide) were assessed after thawing. There was no significant difference between glycerol and ethylene glycol at different concentrations (3% and 5%) regarding sperm total and progressive motility, viability, and membrane integrity. The least percentages of mitochondrial functionality were observed in samples frozen with all different DMSO concentrations tested (P < 0.05). Moreover, the percentage of post-thawed dead sperm was the greatest for all the DMSO concentrations compared with other groups (P < 0.05). Thus, DMSO had an adverse effect on the post thaw ram sperm parameters. In contrast, ethylene glycol could be a desirable substitute of glycerol in the freezing extender, in view of similar results obtained in post-thaw quality of ram semen cryopreserved in a soybean lecithin extender. We propose that glycerol in a soybean lecithin based extender could be replaced by ethylene glycol at 3% or 5% concentrations.