Carbrook Vet Services Reproduction Specialists
Share with friends:

Most horse owners are attracted to the idea of breeding their own foal at some stage, especially those who own mares. Less common, however, is deciding to manage and educate a stallion with the prospect of using him as a sire.

Horses and People magazine’s editor, Cristina Wilkins asked Dr John Chopin, a Registered Specialist in Equine Reproduction based near Brisbane, Australia, some of the most frequently asked questions by both mare owners and those who may be considering managing and breeding a stallion.

What is the difference between artificial insemination with chilled or frozen semen and natural cover?

Stallions can be used for live cover (natural mating) or can have their semen collected for artificial breeding. This artificial breeding can be for fresh, chilled or frozen semen artificial insemination (AI) of the broodmare. The amount of processing the semen undertakes varies but generally increases between fresh and frozen.

Fresh AI is for relatively immediate use. Chilled AI allows storing/transporting semen for up to 48 hours. Frozen semen preserves semen indefinitely and allows both long-distance transport (especially internationally) and long-term storage.

Dr John Chopin, Equine Reproduction Specialist

Why has so much of the breeding moved away from live cover?

There are several reasons why stallions are not used for live cover as much these days and they vary, depending on the aim and wishes of the owner.

There are certain breed society restrictions on the use of artificial breeding. For example, the Thoroughbred industry does not allow any form of artificial breeding, and so, if genetics are to be imported, this requires the stallion to be transported. Today, there are many ‘shuttle stallions’ that travel from one hemisphere to the other and enjoy a very long breeding season!

Artificial breeding with fresh AI can be used when the stallion has too many mares to cover in one day, or it is more convenient for the stallion owner or breeding facility to collect once and inseminate several mares.

Fresh AI is also useful when the mare is not cooperative even though she looks to be at the correct stage of behavioural oestrus. An uncooperative mare is really one that is anxious, frightened and can be aggressive if not managed correctly.

A fearful mare can be a danger to the stallion, people and herself. A decision made by the stallion or the mare owner to collect the stallion and use fresh AI in the mare often saves much heartache in these situations.

Chilled AI allows semen to be transported from the stallion to the mare in a 24- to 48-hour period. This is reasonable when the mare owner cannot, or will not, transport the mare to the stallion and wants the option of having their mare inseminated at a facility of their choice.

Stallion owners who are not in a position to house and handle the mares might opt to drive the stallion to a breeding facility to have semen collected, assessed, processed and transported to the mare.

This option works well for stallions who have an ongoing performance or sports career, for various reasons. For example, the stallion can be conditioned to associate breeding behaviour only with the collecting facility and its staff, allowing the owner/rider to concentrate on their stallion’s training and maintain desired behaviour during competitions.

Training stallions in this way can minimise unwanted behaviours in both, the breeding and training settings, and really help improve a stallion’s mental wellbeing and the relationship he develops with his handlers and riders.

Frozen AI, or the collection of semen for frozen storage, is done for multiple reasons. As well as allowing long-term storage of semen, some stallion owners use frozen semen as an insurance policy, ensuring it is stored in case the stallion is no longer able to breed.

Some owners look to export semen and frozen storage is the most convenient method but requires semen to be collected in an approved facility with quarantine and health testing performed.

And some semen is collected and stored in speculation. For example, a young colt might show some promise, so the owner will store some frozen semen and then have the colt castrated.

How is a stallion collected?

The most common way to collect semen is to have the stallion mount either a mare or a dummy and direct his penis into an artificial vagina or AV. The semen is collected from the artificial vagina, assessed, processed, transported if necessary and inseminated into the mare.

There are other ways to collect semen, though. Some horses can be trained to collect on the ground, a procedure that can be used for an older stallion that might have hind limb pain that prevents him from mounting. Alternatively, chemically induced ejaculation can be used in select cases.

How many people does it take to collect a stallion?

With a very well-trained stallion and experienced personnel, it is possible to have one person handling and collecting the stallion. This, however, is the exception and it is much safer to have a dedicated stallion handler, a person collecting the semen, and a dedicated mare handler if a mare has to be present – making it a total of two or three people.

Is there an optimum reproductive age for stallions?

Stallions mature at different rates and different ages and there can also be some breed differences. Most stallions start puberty between 1-2 years of age, depending on the time of year in which they were born. Final maturation is usually around four years of age.

It is possible to reduce fertility by over-using a young stallion or with the administration of certain drugs. It is essential to carefully manage a young stallion that is breeding to ensure no damage is done to his fertility.

How important is soundness?

A mature stallion with a large breeding commitment needs to be healthy, fit and strong for the season.

Any soreness can become a problem with the stallion potentially refusing to mount, due to pain. Also, the quality and amount of semen can be reduced with a horse that is in pain.

The next point about soundness is an ethical dilemma. The physical appearance of a horse (conformation) is important in determining whether there are likely to have problems with soundness.

Physical characteristics and appearance are also passed on to the offspring therefore, their offspring can inherit the physical appearance of their parents, including some of the problems that may go with that.

How is a mare inseminated?

There are several methods to inseminate a mare. The general principles are cleanliness and no trauma. With a large volume of semen, the method is to use an insemination pipette to place the semen into the body of the uterus.

With smaller semen doses, the ideal is to place the semen further up the uterus, closer to the ovary. This might be achieved with different pipettes that are capable of bending around corners and might require manipulation via rectum, with or without sedation. With very low doses, it is possible to place semen at the very tip of the uterus. This can be done with an endoscope.

What are the pros and cons of these methods of insemination?

Large volume insemination is relatively easy and cheap. The more involved inseminations with low semen doses can be more complex and expensive, as they might require drugs and equipment to achieve insemination.

How long does semen last in the various types of storage?

Fresh semen should be used in a few hours. Chilled semen can last 24-72 hours, depending on the stallion and the way it is processed. Generally, it should be used within 24 hours. Frozen semen can last indefinitely, if it is looked after properly by a professional facility.

How do you ascertain if a stallion’s semen is viable and decent quality?

This can be very important for a number of reasons. If you are considering purchasing a stallion as a breeding prospect, then evaluating the fertility of the horse is very important. Also, if you want to have an idea of how many mares can be booked into a stallion for the season, then an evaluation is important.

If you are considering using chilled semen, there are a number of different extenders and processing methods. Having a test run of different methods will work out which one is the best and, that way, a quality product can be delivered to the mare owner. It is possible a stallion’s semen might not chill or freeze well. This is important to know before offering that stallion for those services.

How do you assess the quality of a stallion’s semen?

Semen is assessed by visual characteristics, volume, concentration and motility. Some of these can be done by eye; the rest need a microscope and associated slides. It is also possible to use computer-aided sperm analysis (CASA). Although CASA is not essential, it does allow some degree of objectivity and repeatability – all important for producing good, consistent results.

Do stallions need to stay at a reproduction facility?

Not necessarily. Some clients prefer to bring them in for collections when they are required. Other clients prefer to leave stallions at a collection facility. The first option reduces costs associated with agistment but places a burden on the owners to make the stallion available on request. The second option removes the need for the owner to drop everything and run the stallion to the reproduction facility, but the workload needs to be considered, so the agistment bill does not exceed income from services.

When is the best time of the year to collect and freeze semen?

Stallions can be collected any time of the year to freeze semen. Our preference is usually to do this at quieter times of the year. The process of freezing semen is more time involved and, in a busy reproduction centre, there is generally more time out of season.

Also, some of the horses who have frozen semen collected need to be trained to do so. It is nicer to work with a naïve stallion when everything is quiet and there is no time pressure that can occur during the breeding season. If semen is being collected and frozen for export, then the facilities and animals have to meet strict quarantine standards. The necessary quarantine isolation of the stallion might be easier to achieve without the heavy traffic flow that occurs during the breeding season.

What factors reduce the performance of a stallion and the quality of his semen?

The main factors that affect quality are age, pain and the use of drugs that impair fertility. A very young horse might not have good quality semen until he reaches maturity. From 14 years of age, semen quality deteriorates, but this is very individual. Some older stallions have very good semen quality, while others deteriorate at a relatively young age. The use of drugs and supplements in performance is a common cause.

Some of these will affect fertility, especially in a maturing individual. If you are unsure of the effect of a drug on a stallion’s potential fertility, consult your veterinarian for advice.

If mare owners choose to breed, how do they start and where do they find a suitable stallion?

Stallion selection can be very difficult and depends on the desired end product.  Evaluating your mare objectively, and matching her with a good stallion is both art and science. Advice from experienced and responsible breeders with a passion for producing quality over quantity, is worth its weight in gold.

Having a working knowledge of popular or performing stallions in your discipline and their bloodlines will help you make an informed decision. There will always be someone nearby who will have an opinion – but sorting the wheat from the chaff can be difficult!

Once the stallion has been selected, budget is a consideration and research into the entire costing of breeding, including service fee, agistment and veterinary fees, is important. These will vary depending on the type of breeding that is done.

Research into fertility results with your selected stallion might be difficult to obtain, but some stallion owners are very open about what they think their stallion fertility results are. Having your mare examined by a veterinarian is also important. Ideally, this should be done before or early in the season, so the veterinarian can identify any obvious problems and possibly correct them before too much time is lost.

Is there any post-breeding veterinary care that mare owners need to consider?

Most mares have uneventful pregnancies and births. If there is a history of problems with your mare, then discussion with your veterinarian can help come up with a management plan for pregnancy. Overall, keeping these mares in good to fat condition (not obese) produces the best foal possible with very little problems during pregnancy and birthing.

Developing a good working relationship with your equine reproduction specialist veterinarian will be useful if any problems should arise.

Dr John Chopin BVSc, PhD, FANZCVS, Registered Specialist in Equine Reproduction
Dr John Chopin, BVSc, PhD, FANZCVS, Registered Specialist in Equine Reproduction

John is a graduate of the University of Queensland, and finished with a PhD in equine frozen semen and ovulating agents. His extensive experience in large-scale breeding operations includes working with Australia’s first commercially used clone stallion. John has consulted to numerous practices and companies, runs continuing education to veterinarians and has published over 60 articles, including book chapters in leading texts in equine reproduction. John continues to have an interest in clinical research.

Share with friends:

Leave a Reply

Your email address will not be published. Required fields are marked *