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Title: Opportunities to improve liquid and frozen storage of boar semen

Author
item Guthrie, Howard
item Welch, Glenn

Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/2008
Publication Date: 3/17/2008
Citation: Guthrie, H.D., Welch, G.R. 2008. Opportunities to improve liquid and frozen storage of boar semen. Journal of Animal Science, 86, E-Suppl. 3: 45-46.

Interpretive Summary:

Technical Abstract: Artificial insemination has facilitated the utilization of superior genetics, and has reduced boar biosecurity problems and housing costs. The use of frozen semen permits the flexibility to inseminate animals at unscheduled times and to use semen of deceased boars. While good long-term storage extenders for liquid semen have been developed, the composition of semen extenders should be redesigned to improve energy production and utilization in sperm cells, which decreases after 5 d of hypothermic storage compared to fresh semen. Frozen semen is not widely used in the swine industry because the technology is difficult, but the primary problems with frozen-thawed semen are that 50% of the cells are killed and surviving cells must be inseminated during the 4 h interval before ovulation to optimize fertilization. Different combinations of permeant and impermeant cryoprotectants and different methods of their application to sperm cells are being tested to increase the resistance of sperm to osmotic stress, temperature change, disruption of membrane lipids and proteins, and ice crystal formation. Cyclodextrin delivery of cholesterol into sperm cells increased the resistance of sperm cells to osmotic stress and increased post-thaw motility and viability, but the impact on fertility is unknown. Progress in the use of frozen boar semen may be achieved through genetic analysis of boar lines at the USDA Meat Animal Research Center with > 60% sperm survival after freeze-thawing. Attention to the timing of insemination to relation to ovulation can improve sperm fertility using current freezing technology. We used a single, fixed time insemination of 5 x 109 thawed sperm 0-4 h before the expected time of ovulation in 40 altrenogest-treated gilts (controlled by an injection of 750 IU of hCG i.m. 130 h after the last feeding of altrenogest). The farrowing rate was 75% and the mean number/litter of pigs born, born alive, and weaned were 9.7, 8.8, and 8.6, respectively. Use of frozen boar semen is facilitated by the fact that it can be held for 48 h in commercial extenders before freezing without impairing farrowing rate. We believe that changes in semen extender composition and improved application of cryoprotectants will improve the fertility of liquid and frozen semen.