Cryopreservation of semen from domestic livestock

In modern livestock breeding, cryopreserved semen is routinely used for artificial insemination. Sperm cryopreservation secures future reproduction, and insemination doses can be easily shipped. Processing of semen for cryopreservation can be done with minimal efforts and relatively low costs. In this chapter we describe the entire cryopreservation process for stallion and bull sperm including dilution of sperm in primary and freezing extender, cooling and packaging in straws, freezing in liquid nitrogen vapor, cryogenic storage, and thawing. Special emphasis is given on preparation of commonly used primary and freezing extenders (skim milk extender "INRA-82", TRIS-egg yolk extender "TEY") used in a two-step dilution approach. Furthermore the different cooling rates needed in different temperature regimes during the freezing process are being described. Cryopreservation procedures are described in case of using both specialized automated equipment and simple equipment.