Artificial Insemination from the Stallion's Veiwpoint

Earlier this spring, I wrote a blog about artificial insemination in mares. This blog will detail the steps involved in collecting semen, evaluating and processing semen from a stallion for artificial insemination. This picture shows our equine semen lab which contains all our equipment for collecting stallions and breeding mares.

Most of the stallions we collect at the Arthur Veterinary Clinic are trained to jump or mount an artificial dummy or phantom. Some stallions require a mare in heat to tease or become aroused. Other stallions need very little teasing to approach and jump the dummy. For the stallion that has never been collected, a mare in heat is placed alongside the dummy. Most stallions are very trainable and adapt quickly to jumping the dummy and being collected with an artificial vagina. Below is a picture of our equine dummy or phantom.

Equine semen if very sensitive to temperature changes. When handling equine semen, it is very important not to temperature shock the semen. Therefore, any supplies or equipment which come into contact with the semen must be at body temperature (98.6 degrees Fahrenheit or 37 degrees Celsius). We have two large incubators which keep all supplies and extender at a warm, toasty temperature of 98.6 degrees!

Collection of the Stallion

Semen is collected from a stallion with an artificial vagina (AV). There are several types of AVs used to collect stallions. Pictured below is the Colorado Model which we use at the Arthur Veterinary Clinic. Basically, an AV consists of an outer casing which houses some sort of liner. Attached to the liner is a bottle which collects the semen. We use a baby bottle liner (used for infant baby bottles) inside the collection bottle. This allows us to discard the liner after collection and reuse the bottle without washing the bottle. A filter is placed inside the liner in the bottle to separate any gel and debris from the collected semen. We place a beverage can "huggie" around the collection bottle to maintain the temperature.

The AV is then filled with warm water. The temperature of the water used to fill the AV and the amount of water used varies depending on the individual stallion. After the AV is filled, the inner liner is lubricated with non-spermacidal gel.

When the AV is assembled and lubricated, the stallion is then brought to the breeding area. The stallion's penis is washed with warm water and he led to the dummy. As he mounts the dummy, the AV is placed on his penis.

Once the stallion has ejaculated, the water is drained from the AV and the collection bottle is removed and taken into the semen lab where the filter is removed and discarded.

Evaluating the Semen

Once the semen is collected and the filter is removed, it is important to either place it in an incubator or on a warming plate to maintain the temperature. Here is a picture of semen being poured from the liner into a cylinder placed on a warming plate. The volume of semen is measured and noted at this time. The two main parameters measured when we collect equine semen are motility and concentration. Motility is an objective measurement taken by viewing the semen on a microscope. Motility is defined as forward, progressive movement......meaning the sperm should be moving in a forward direction, not spinning around in circles. Motility is vital to fertility. Without good motility, a stallion will not achieve pregnancies. In other word, a stallion can have a 100% live sperm sample with a high sperm count but if the sperm are not moving in a forward direction, he will be infertile. Motility is expressed as a percentage. Ideally, a fresh sample will have 70% or greater of forward, progressive sperm. Below is a picture of our videomicroscope used to analyze semen. A videomicroscope is a microscope attached to a video screen to allow better visualization of the semen......and it also allows clients to see the sample.

The next parament measured is the sperm concentration. We use the densimeter manufactured by Animal Reproductive Sytems.
A small sample is placed in the densimeter which then determines the concentration of sperm.

(We have a polite densimeter......"one moment please"....)

The concentration is expressed as a number per volume of sperm which is reported as X million sperm per milliliter of volume. This number is variable depending on the stallion. It can range from very low 50 million/ml (or lower) to very concentrated 350 million/ml (or higher). For the most part, the higher the concentration the better. For maximum fertility, very dilute semen must be centrifuged to increase concentration. And, believe it or not, the large draft stallions tend to have the lowest concentrations or the most dilute semen.
Once the concentration is obtained, then the total volume collected and the motility concentration is entered into the densimeter to obtain to the total number of sperm. The total number of sperm determines how many mares can be bred with a single collection sample. Here is a picture of Dr. Scott entering motility and volume data.

Packaging the Semen

When packaging equine semen, we always use extender. Basically, semen extender is full of nutrients which allows the semen to live longer and stay healthier while it awaits deposition into the mare's reproductive tract. Its kinda like a "energy bar" for sperm.....except in liquid form and they bathe in it! There are several different brands of commercially prepared extender. We prefer the INRA brand. And remember, the extender must be warmed to 98.6 degrees before being added to the semen.

Depending on whether the semen is going to be used immediately, on farm, or cooled for transport, the densimeter goes on to calculate the volume of extender and the volume of semen needed to package together for a breeding dose. 500 million sperm are used for on farm breeding while 1 billion sperm are used for cooled, transported semen.
The last step in packaging the semen is mixing the proper amount of extender with the proper amount of semen. The breeding doses are either packaged in whirlpac bags or syringes. If breeding on farm, the sample is immediately inseminated in the mare. If the semen is being cooled, it is placed in a specialized container which cools the semen at a specific rate and then maintains that temperature. Below is a picture of an Equitainer shown with the specialized coolant can. This picture is of a disposable shipping container.
These containers are then sent either overnight with FedEx or UPS or sent the same day via an airplane. If we are sending semen on an airplane, we call ahead for flight times. We have someone drive the shipping container to the airport located at the University of Illinois and purchase a cargo ticket for the shipment. Since the attacks on September 11th, only cargo shipments from "approved shippers" are allowed. The Arthur Veterinary Clinic is an "approved shipper" on American Airlines.
Reading this blog, you may think that this process takes forever. However, when collecting an experienced stallion, the whole process from start to finish takes around 20-30 minutes. While there are several steps involved, it takes much less time than it did for me to write this blog!