Effectiveness of different boar semen storage techniques

Abstract

This review surveys the techniques used for the preservation of semen in the liquid or frozen state. As regards storage in the liquid state, several diluents have been developed to preserve the fertilizing capacity of semen for several days. In order to obtain the highest conception rate and prolificacy, it seems necessary to use the total fraction of ej aculate and to dilute semen in B.T.S. medium to 3 x 10⁹ spz/100 ml. In such conditions, the fertilizing capacity is preserved for up to 3 days after collection without reduction in conception rate and prolificacy. As regard storage of deep-frozen semen, several methods have been developed. Semen quality after thawing varies according to the freezing-thawing diluents used and to the techniques of preparation and storage. Electronic microscopic analysis of spermatozoa and their environment after cryosubstitution, shows that dehydration at freezing is an important factor for the preservation of semen quality after thawing, at least as regards the acrosome integrity. Results of artificial insemination performed during the last 10 years do not show any difference between the use of straw or pellets for the deep-freezing of boar semen with respect to the farrowing rate and prolificacy. However, other factors such as insemination period, inseminator and boar may affect fertility. In conclusion, frozen semen used for A.I. can be expected to result in a conception rate of to 20 to 30 % lower and in a litter size of about 1 to 3 piglets less than does fresh semen.