A stallion produces untold billions of sperm during a lifetime, and in a normal ejaculate, he can send four billion of them on a race to fertilize a single egg. Only one sperm can succeed. Unfortunately, there are times when none of them succeed. The result is an open mare, something that can cost the mare owner time, money, and patience.

There are multitudes of reasons why sperm fail to fertilize an egg. In some cases, the problems that exist can be solved. In other instances, they can’t, and the stallion is retired from the breeding shed.

While not every troublesome condition can be solved for the stallion, the stallion manager at least has at his or her disposal a method for determining whether the horse is fertile–semen analysis.

Before getting into the topic of semen analysis, we should understand what it is we are discussing