Effect Of Epimedium Polys Accharides On Boar Semen Cryopreservation

Frozen-thawed boar semen is presently used for international exchange among nucleus farms to help maintain genetic diversity. Frozen-thawed boar semen can provide increased flexibility for on-farm use and allow additional time for disease tests. These boar semen cryopreservation methods/procedures were applied mainly where transfer of blood lines or export was the need, still, they were not widely used for standard pig production. The limited use of frozen semen could be directly attributed to the procedures as well as the reduced fertility and litter size. Researchers have done a lot of work on improving boar post-thawed semen quality. Recently, developing new low toxicity cryoprotectants (e.g. DMF, DMA, MF and some other amides) and attempts to add some protectants (sugars: Trehalose, Rhodiola polysaccharide and so on; antioxidants:Melatonin, Glutathione, Vitamin E, Superoxide dismutase and the like) into freezing extender are paid more much attention. However, it is a tough work to improve frozen-thawed boar sperm quality. Exploring new methods to improve post-thawed boar sperm quality is of great research meaning and application value. Based on the survey of boar semen quality, in this experiment component of traditional Chinese medicine-epimedium polysaccharide (EPS) was added to modify freezing extender and thawing extender in boar sperm cryopreservation and its effect on post-thawed sperm quality was tested. This study aimed to provide the foundmental information for further research on the role, mechanism and application of epimedium polysaccharide in boar sperm cryopreservation. The main content of this experiment as follows.Experiment1. A survey on boar semen quality and its relationship with post-thawed sperm qualityThe semen quality of Landrace boar is best from January to June, with its ejaculating volume over250mL and a good viability, while from July to August it gets to the worst. Generally, the ejaculating volume of Yorkshire boar is relatively small, varying from50mL to200mL. Its semen quality is steadily good from November to December. However, the ejaculating volume varies in a wide range from April to October. For Duroc boar, its ejaculating volume varies from100mL to400mL, intensively from150mL to300mL. The worst time of its semen viability occurs from July to September, while the steadily good semen viability obtained from Octorber to the next April. To minimize the boar semen viability lose during transporting, we dilute fresh semen in a rate of1:1with ZOPVA solution at the same temperature, and transfer semen into a glass bottle which is kept in a thermos. Relationship between fresh semen quality and its post-thawed quality was analyzed and as a consequence correlation between fresh sperm density and post-thawed sperm viability is significant (r=0.4316, P<0.05), while correlation between fresh sperm viability and post-thawed sperm viability is greatly significant (r=0.5623, P<O.01). Significant correlation between fresh semen quality and post-thawed sperm motility was observed.Experiment2. Boar semen cryopreservation with0.25ml strawThe study is aiming to explore the effect of factors in freezing and thawing procedure on post-thawed semen quality. The results as follows:After diluting fresh semen with ZO-PVA, semen treated differently (pre-equilibrated at17℃,37℃or room temperature) has insignificant difference in post-thawed viability. Cryopreservation of boar semen with a sperm density of1×109/mL and0.5×109/mL has insignificant difference in post-thawed viability, while with a sperm density of2×109/mL leading to a viability below0.1. Cryoprotectants1%Gly+2%DMF,1.5%Gly+1.5%DMF and3%Gly were used in boar semen cryopreservation respectively and no significant difference between groups in post-thawed semen quality was observed, which implies the feasibility of using1%Gly+2%DMF or1.5%Gly+1.5%DMF as cryoprotectants instead of3%Gly. But further study on that is required. For the thawing procedure, post-thawed semen was stored respectively at37℃,30℃or room temperature, or treat straw in room temperature without dilution into ZO solution, there is no significant difference in post-thawed viability among groups.Experiment3. Protective effect of epimedium polysaccharide on cryopreserved boar semenBetter parameter of post-thawed viability, plasma integrity and intact acrosome was obtained after adding a concentration of4mg/mL epimedium polysaccharide into freezing extender. Then a concentration of2mg/mL epimedium polysaccharide was supplemented into thawing solution, which results in a parameter of0.54in post-thawed viability,62.7%in plasma integrity and53.0%in intact acrosome. Different conservation temperature has significant effect on post-thawed sperm lifespan. The results show that room temperature benefits sperm lifespan the best. Sperm viability declines from0.54to0.404h after thawing, and6h after thawing it got to below0.3, which allows sufficient time for the application of post-thawed sperm.