Effect of the addition of lemon balm (Melissa officinalis) to ram semen extender for cryopreservation

Background: During cryopreservation, oxidative stress exerts physical and chemical changes on sperm functionality. The main objective was to study the effects of the addition of lemon balm (Melissa officinalis) to ram semen extender for cryopreservation on sperm function.Methods: Semen samples were collected from four ghezel rams by an artificial vagina twice a week. The ejaculates containing spermatozoa with > 80% forward progressive motility and concentrations higher than 3 × 109 spermatozoa/ml were pooled and diluted in soy bean lecithin extender, with the addition of 0, 1.5, 3 and 6 mg/mL of lemon balm (Melissa officinalis). The diluted semen was cooled at 4 ◦C and loaded into the straw and then stored in liquid nitrogen. After thawing, sperm motility and motion parameters were assessed using a CASA system. Sperm viability, membrane integrity and lipid peroxidation were assessed by eosin–nigrosin, HOST and MDA test, respectively.Result: The extender supplemented with 3 mg/mL of lemon balm resulted in higher sperm motility and progressive (p < 0.05) in comparison to the control group. Also, addition of 1.5 and 3 mg/mL of lemon balm improved significantly viability after freeze–thaw. The supplementation of freezing extender with 3 mg/mL of lemon balm reduced sperm lipid peroxidation.Conclusion: In conclusion, the results of the present study demonstrate that addition of 3 mg/mL of lemon balm have beneficial effect on quality of post-thawed ram semen.

Keywords:

Oxidative stress , Sperm motility , Lemon balm (Melissa officinalis)