view - Department of Reproduction, Obstetrics and Herd Health

PREFACE
The first recorded case of artificial insemination (AI) in horses goes back to the Arabs in 1322,
when a chief decided to steal semen from a rival’s stallion to use for one of his own mares (Bowen,
1969). Still, it wasn’t until 1677 that spermatozoa were actually visualized by van Leeuwenhoek and
Ham using one of van Leeuwenhoek’s first microscopes. These so called “animalcules” were
described as living creatures with a tail and have been studied ever since. In 1781, Spallanzani
described the influence of temperature on the motility of these animalcules. He found that cooling in
ice reduced their motility, and after subsequent warming the animalcules became motile again
(Gonzalès, 2006).
Between the first reported AI from the Arabs and the research during the late 19 th century by
Sir Walter Heape, equine AI languished in silence. Early research in reproductive work was done by
Heape, a student from the University of Cambridge and a pioneer in embryo transfer in the rabbit
(Heape, 1890). He also collected semen from a stallion followed by successful inseminations in mares
(Heape, 1898). Continuing research in horse reproduction and in utero development was performed
by Sir John Hammond, who carried out reciprocal inseminations of Shire mares with Shetland stallion
semen and vice versa to examine the maternal effect on growth and conformation (Walton and
Hammond, 1938). Unfortunately, most of the early work which was done by the Russians and the
Chinese between 1930 and 1960 remained unpublished, hidden by the Iron Curtain and language
barriers (Allen, 2005). In the late 1960s, equine AI revived with the work of B.W. Pickett and his large
group of co-workers who worked on the collection, dilution, cooling, freezing, and insemination of
stallion semen. Much of this work is summarized by Squires et al. (1999).
The acceptance of AI by the majority of horse breed registries and the possibility to transport
cooled and frozen semen, have changed the entire horse industry and equine reproduction in
particular. This widespread use of “processed” semen does not only increase the breeder’s
possibilities but also surfaces challenges for the researchers and veterinarians harvesting and
preparing these AI doses. First of all, there is the never ending quest to increase the pregnancy rates
(requiring improved processed semen), and secondly, following human andrology, standards need to
be formulated when examining that semen, so the quality can be assessed worldwide using the same
criteria.
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