The effect of adding Evening primrose (Oenothera biennis) seed oil to Tris extender onram semen quality after freeze-thawing process Romanov

Studies had shown that excessive production of free radicals during sperm processing decreases its quality parameters including motility, viability, and fertilizing ability. Therefore, it seems necessary to use a compound with antioxidant properties during this process. Evening primrose oil has antioxidant properties due to its phenolic compounds. the purpose of this research is to investigate the effect of adding evening primrose seed oil to freezing diluent on the quality of ram sperm after freezing and thawing process.

In this research, the semen of 5 adult Romanov rams with an average age of 3 to 4 years and average weight of 60 to 65 kg were used. Semen collected using artificial vagina from trained rams twice a week. The treatments included control (without evening primrose seed oil), treatment 1 with 25 microliters EPSO, treatment 2 with 50 microliters EPSO, treatment 3 with 100 microliters EPSO. The collected semen sample to laboratory and examined in terms of volume, concentration and motility. Semen samples were diluted with a diluent based on Tris- lecithin soy and frozen. After thawing, parameters of general mobility and progressive mobility and other parameters related to mobility were evaluated. The survival percentage, membrane integrity, mitochondrial activity and peroxidation were determined.

The results showed that the level of 25 microliters of evening primrose seed oil improve the motility of the whole sperm compared to the control group, and no significant difference was observed in other experimental treatments compared to the control group. There was no significant difference between the 25 and 50 microliters treatments with the control group in the progressive parameter, but there was a significant difference with the 100 microliters treatment compared to the other treatments and the control treatment(P<0.01).The results of lipid peroxidation showed that the lowest amount of Malon-di-aldehyde production was related to the 25 microliters treatment but no significant difference was observed with the control treatment. The results of the apoptosis test showed that the addition of levels of 25 and 50 microliters of evening primrose seed oil decreased the amount of apoptosis compared to the control group and the level of 100 microliters of evening primrose seed oil(P<0.01). Also, survival in the treatment of 25 and 50 microliters compared to others The treatments had a significant difference and increased survival(P<0.01). And finally, dead sperms in the 25 microliters treatment were less compared to other experimental groups, and this caused a significant difference in this trait compared to other levels(P<0.01).

In general, the addition of evening primrose seed oil in the freezing diluent leads to an increase in the viability and health of the plasma membrane of sperms after thawing. Adding 25 microliters of evening primrose seed oil to the diluent caused a significant difference in the parameters of lipid peroxidation and apoptosis compared to the control treatment.