view - Department of Reproduction, Obstetrics and Herd Health

1.1.1. Introduction
CHAPTER 1.1
The widespread increased use of artificial insemination (AI) in domestic animal reproduction
implies a growing awareness concerning the male’s fertilizing potential. Indeed, the fertility of one
individual male can have an enormous impact on the pregnancy outcome of hundreds of females. As
such, the economic importance of male fertility in breeding animals has increased proportionally.
Focusing on livestock, the financial interests are equally important for business both for
owners of male and female breeding animals. For the male side, more insemination doses represent
a higher income for the breeder or AI company, but the downside can be that lowering the dose
might result in a decreased conception rate (Chenoweth et al., 2010). This will affect the production
results and might lead to law suits against the AI companies that are involved. International
guidelines on the minimal quality requirements for an AI dose would protect the owners of the
female animals but could also provide insurance for the male counterpart. However, before those
uniform international guidelines for different animal species can be established, a consensus is
required on techniques and settings used for semen analysis. After all, methodology of analysis has a
major influence on the outcome parameters.
In many aspects the equine breeding industry is comparable with the production animal
breeding industry, although there are some striking differences. In the latter, the importance of a
given positive trait (e.g. faster growing rate, higher milk production) might be less attractive for
selection when associated with markedly decreased fertility. This is in sharp contrast with equine
breeding, where selection is most often based on breed characteristics such as phenotype or sports
performance. Consequently, a possible reduced fertility outcome becomes only important in the long
run. Additionally, a superior performing stallion with decreased fertility might even be more
attractive to breeders of sport horses, as breeding with this stallion will not only lead to offspring
with a high performance expectation, but due to its subfertility it will also result in a low number of
foals. The game of supply and demand will thus increase the value of the offspring even more.
Due to great demands of AI doses from famous, popular stallions, normal fertile stallions
might seem subfertile. At a given time a (too) popular stallion might breed more mares than there is
semen available, which will very often result in more AI doses containing lower numbers of sperm.
Eventually, this might lead to a decreased conception rate and increased costs for the mare owners.
Therefore, regardless of the intrinsic fertility of a stallion, minimum requirements for an AI dose
concerning number and quality of the sperm might provide an assurance for the breeders.
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