Cryopreservation of boar semen I. The effect of the deep-freezing on the boar spermatozoa. Literature review

Cryopreserved boar semen has been commercially available since 1975 but nowadays the use of frozen thawed sperm in artificial insemination technologies represents around 1% of total inseminations. This limited use is mainly due to the poor reproductive output obtained with frozen-thawed sperm compared to fresh-chilled semen. Frozen semen requires two to three times more sperm per insemination, the litter size is about two to four piglets per litter less, and the farrowing rate is lower. The success of fertilization depends basically on their lower post-thawed quality resulted from deep-freezing and/or the modified steps of artificial insemination. The authors give a review about the detrimental damages and changes of boar spermatozoa which should have to be minimized or avoided to improve the fertilizable capability of deep-frozen boar semen.