Frozen Semen Processing and Quality Control

The first pregnancy obtained by using frozen-thawed semen in the equine species dates back to 1957 (Barker and Gaudier 1957) and was obtained using epididymal semen. Nonetheless, for many years, this reproductive technology has achieved limited progress in the horse compared with other species (e.g. cattle). This was mainly due to the fact that for a very long period of time only a few horse registries allowed the use of frozen-thawed equine semen: hence, economic interests and resources allocated to research have has always been minimal, thereby obstructing advances in this area. Today, almost all the horse registries allow the use of this reproductive technique, thus encouraging researchers to focus on identifying better semen freezing techniques and simpler artificial insemination protocols. This has resulted in an improvement in fertility of cryopreserved equine semen, further enhancing the use of the technique by breeders. Moreover, a few papers published over the last few years (Loomis, 1999; Vidament, 2005; Loomis and Graham, 2008) clearly showed that the development of improved techniques for freezing equine semen allowed a greater percentage (85-90%) of stallions, than has traditionally been reported in the literature, to be capable of producing semen with commercial acceptable post-thaw quality.