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Title: Implications of the pH and temperature of diluted, cooled boar semen on fresh and frozen-thawed sperm motility characteristics

Author
item Purdy, Phil
item THARP, N - Purdue University
item STEWART, T - Purdue University
item Spiller, Scott
item Blackburn, Harvey

Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2010
Publication Date: 9/20/2010
Citation: Purdy, P.H., Tharp, N., Stewart, T., Spiller, S.F., Blackburn, H.D. 2010. Implications of the pH and temperature of diluted, cooled boar semen on fresh and frozen-thawed sperm motility characteristics. Theriogenology. 74:1304-1310.

Interpretive Summary: Boar semen is typically collected, diluted and cooled for AI use over numerous days, or frozen immediately after shipping to capable laboratories. The storage temperature and pH of the diluted, cooled boar semen could potentially influence the fertility of boar sperm. Therefore, the purpose of this project was to determine the effects of pH and storage temperature on fresh and frozen-thawed boar semen quality. The commercial stud was responsible for the greatest variation in semen temperature and pH, as well as total and progressive motility, and numerous other sperm motility characteristics. The pH was not a significant source of variation for fresh or frozen-thawed boar sperm motility characteristics. However, storage temperature, boar and the commercial stud influence sperm quality and the potential success for surviving cryopreservation. These results indicate that maintaining cooled boar semen at approximately 16 ºC during storage will result in higher fresh and frozen-thawed boar sperm quality. Consequently, if commercial and private studs ship their cooled boar semen samples at 16 ºC this will result in greater sperm quality, and potentially fertility, for the producers.

Technical Abstract: Boar semen is typically collected, diluted and cooled for AI use over numerous days, or frozen immediately after shipping to capable laboratories. The storage temperature and pH of the diluted, cooled boar semen could potentially influence the fertility of boar sperm. Therefore, the purpose of this project was to determine the effects of pH and storage temperature on fresh and frozen-thawed boar semen quality. Semen samples (n=199) were collected, diluted, cooled and shipped overnight to the National Animal Germplasm Program laboratory for freezing and analysis from four different boar stud facilities. The temperature, pH and motility characteristics, determined using computer automated semen analysis, were measured upon arrival. The samples were then cryopreserved and the post-thaw motility was determined. The commercial stud was a significant source of variation for mean semen temperature and pH, as well as total and progressive motility, and numerous other sperm motility characteristics. Multiple regression analysis revealed that pH was not a significant source of variation for fresh or frozen-thawed boar sperm motility characteristics. However, significant models were derived which demonstrate that storage temperature, boar and the commercial stud influence sperm quality and the potential success for surviving cryopreservation. These results imply that by maintaining cooled boar semen at approximately 16 ºC during storage will result in higher fresh and frozen-thawed boar sperm quality which should result in greater fertility.