Ten of your FAQ’s answered about Artificial Insemination

This article is from the September 2020 Horse Deals magazine.

Artificial Insemination (AI) has been used for decades now for most breeds in the equine breeding industry. At the start of every breeding season, many questions get raised regarding the process, the pitfalls and how to make it more successful.

Am I prepared to have a foal from my mare?

Do you have enough facilities to cater for a pregnant mare and a foal once it’s delivered? Adequate facilities are essential to allow foaling in a safe, controlled environment and access to stabling should be considered an advantage if the foal requires it after birth. Not all properties have appropriate fencing for foals and youngsters who are naturally inquisitive and clumsy. Wood post/rail, metal post/synthetic electrified rails and wooden post/top rail with fine wire mesh are the popular choices for studs. 

If this is your only horse, have you considered she may be out of action for riding and competing for 18 months? Have you looked at the costs involved in each step of the process, including care and handling of the foal as it grows up? 

The breeding season starts at the beginning of September and draws to a close in late summer. Depending on the discipline, it may be desirable to have a foal early in the season to gain the size and maturity advantage, but if you are in a colder climate area then stabling may need to be available if the weather turns nasty.

Is my mare a good candidate for AI?

It is fair to say that we can see our horses through rose-tinted glasses! These should be removed so you can evaluate if your mare is good enough to be producing a foal. Is she of sound temperament? Behavioural traits are hereditary, so putting your mare in foal because you can’t ride her may not be a valid reason. Is her conformation good enough to pass onto her offspring? 

Age is an important consideration. Regardless of age, a breeding soundness examination should be carried out before the AI process begins. For young maidens, this may only involve an examination of the reproductive tract at the start of the season to check everything looks normal. For older mares, a uterine biopsy may be a useful indicator of endometrial health and youthfulness. Clitoral and uterine swabs are also indicated to rule out venereal diseases which would hinder conception. Older maiden mares can pose more problems than a multiparous mare of the same age. Uterine tone can become sluggish with age and the cervix can be tight and fibrotic which may result in unwanted fluid accumulations in the uterus after breeding. High levels of veterinary intervention may be needed for a successful outcome with these ‘susceptible mares.’

Which is the best stallion choice?

It is important to choose a stallion which compliments your mare’s conformation, ability and temperament. Next, is to check the availability of the semen. Is the stallion in another country? Chilled semen can be shipped from New Zealand, but only frozen semen is available from other countries, e.g. USA or Europe. Stallions need to undergo rigorous health testing and a quarantine period prior to freezing for their frozen semen to be suitable for importation to Australia. It is important to check if the semen you want to use can be imported. There are various agents in Australia which makes the process of ordering semen from abroad much easier for the individual. If frozen semen is the only available option for the stallion of your choice, then it may be beneficial to choose a Plan B in case your stud vet suggests frozen semen may not be suitable for your mare. 

What is the difference between fresh, chilled and frozen semen?

Fresh semen has minimal, if any processing prior to insemination. This may be an advantage to use in ‘susceptible mares’ mentioned earlier. The mare needs to be at the same facility as the stallion, as it needs to be placed in the mare within ten minutes of collection. However, once in the mare, fresh semen may last up to 48-72 hours. 

Chilled semen has a semen extender added to it and it is placed in a special polystyrene box with an ice block designed to chill the semen to around four degrees and keep it chilled until it is ready to inseminate. This semen may last up to 48 hours, so overnight shipping is possible. A higher degree of veterinary management is required to ensure ovulation occurs while the semen is still viable. 

The stud fee for chilled and fresh semen generally includes ‘terms’, i.e. a limited number of pregnancy attempts with the same mare can be made, ‘no foal, free return’ or 50% of stud fee back if the mare is negative at the end of the season.

Frozen semen. A special extender which includes cryoprotectants is needed to freeze semen. It is stored indefinitely in liquid nitrogen, so old or dead stallions can be available to use. There is much more processing involved and once thawed, the semen may only last for six hours. Hence, special management is needed to ensure the mare is set up appropriately for insemination with frozen semen to avoid disappointment. Mares can react more to frozen semen, so more aftercare may be needed post-insemination. The additional processing required for freezing can often pose a problem for certain stallions’ semen. Different extenders and freezing processes can be tested for these stallions, but there are some whose quality never makes the grade for sale. Terms of sale for frozen semen are often less attractive than with chilled and fresh semen contracts. It may be bought per straw, dose or a limited number of doses. It is advisable to establish a good understanding of the terms before purchasing and consider how it will affect your budget if the mare isn’t pregnant first time around.

Can I have my mare inseminated at home?

Communication between you and your stud vet is very important. Insemination, in particular with chilled semen, can be carried out at your premises. However, it will depend on the facilities you have to offer. It is ideal to have a crush for the safety of your vet, provision of clean water, and electricity may be needed for an ultrasound machine. If your vet is based a long way from your premises, then it may be easier and more efficient to spend a few days at the clinic. There are many specialist breeding centres and studs where you can send your mare and have her home once she has reached 45 days pregnant. 

What can I do to improve her chances?

Nutrition is very important throughout the whole breeding process. It is better for a mare to be of a consistent weight; being obese is just as bad for fertility as being too thin. A range of balancers and concentrate feed are available for breeding stock and Omega 3 FA’s can improve fertility. During the breeding process, it is advisable to keep stress levels to a minimum and be aware that heat stress can really affect fertility. Exercise need not be off the agenda, but it is wise to avoid exercise during the hottest part of the day or stressful competitions around conception.

What does the process of AI involve?

At the initial breeding soundness examination, the vet will determine where the mare is in her reproductive cycle. A prostaglandin injection may be administered to bring her into season. When chilled semen is being used, regular communication by you or your vet with the stallion owner/semen collection facility needs to be established to confirm availability of semen and to give plenty of notice that a collection will be needed. It is possible to manipulate her oestrous cycle to facilitate collection and shipping on a weekday. Once the semen collection is confirmed and estimated time of delivery is known then the mare can be given an ovulation induction drug to facilitate ovulation soon after insemination. Frozen semen is released to your vet from the stallion owner once you have paid for it. The frozen semen is stored in a tank until the vet needs it, so in some respects, it is logistically much easier than having to order and set up a mare for chilled semen. 

Why does my stud vet need to see my mare after insemination?

A post insemination ultrasound examination is usually carried out 6-24 hours after insemination. Confirmation of correct timing of ovulation and treatment of accumulated fluid in the uterus is essential for a positive outcome.

When do I find out if we are successful?

Pregnancy scans are routinely carried out at 14, 28 and 45 days after ovulation. The first scan establishes if insemination has been successful. Careful attention is paid to whether there is only one conceptus, as the next 48 hour period is the safest time frame to effectively terminate an additional pregnancy. The 28-day pregnancy check confirms the presence of a fetal heartbeat, and the 45-day check is used as a final scan after which the pregnancy is less likely to fail. Additional scans may be advised throughout the pregnancy if there are any signs of abnormality. 

What happens now?

Your mare still needs to be looked after during pregnancy with regular farriery, drenching and attention to diet. Avoid the temptation of over-feeding, keeping to good quality forage and balancer if not in work. Addition of extra concentrate feed is only recommended if her condition score declines or in the last couple of months before foaling, when it can gradually increase in preparation for milk production. A 2 in 1 booster vaccine is recommended four to six weeks before foaling, and a course of Herpes vaccines may be recommended by your vet depending on circumstances and contact group. 

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