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Modern pig production is vertically integrated, with breeding done through AI. This firstline, easy, practical and highly effective biotechnology serves two major purposes (i) avoid spreading venereal (or otherwise semen-shed) diseases and,(ii) maximise dissemination of genetic material to large numbers of sows. With proper detection of oestrus (twice daily) and AI correctly performed (80-100 mL, cervical, 2-3 times/oestrus) with high-quality semen (> 2 x 109 motile spermatozoa),> 90% of farrowing rates and mean litter sizes of 12–14 piglets are reached, comparable with those achieved with natural mating (reviewed by Rodríguez-Martínez 2007a). With such results, it is not surprising that pig AI became an essential breeding tool, increasing worldwide from~ 7% at the start of the 1980s (Reed 1985) to more than 80% 20 years later (Wagner & Thibier 2000). In the European Union (EU)~ 84% of all sows/gilts are bred by AI (Feitsma, personal communication). Improvements in the design of media, AI-catheters and moment of AI, have led to> 99% of all AIs done around the world being made with liquid semen (Wagner & Thibier 2000). Frozenthawed (FT) semen is, however, rarely used (~ 1%, Thibier, personal communication), since cryopreservation is still considered “quasi experimental”. However, breeding enterprises are interested in further developing cryopreservation, since FT-semen could be used in situations in which the widely used liquid semen can not, such as the international exchange of genetic lines without transporting livestock, the long-term conservation of superior genetic individuals in genetic resource banks, or the testing for …