Choosing a stallion

If you’re planning on breeding from your mare this season choosing the right stallion is one of the most important decisions you will have to make. You have no doubt been reading the stallion catalogues, browsing the internet and visiting the many stallion parades around the country to find the perfect match for your mare.


Things like breeding lines, conformation, performance record, current progeny and temperament will have likely influenced your decision so far. But let me urge you to consider just one more factor before you make your final choice: the likelihood of getting your mare in foal with this stallion. You can choose the nicest stallion in the world but if you don’t have a successful pregnancy then all of your time, money and emotions will be wasted. Here are my tips and questions you should be asking when considering a stallion, they are from a personal perspective of breeding my own foals (and my lessons learnt the hard way) and from my experience as an equine vet getting mares in foal.


  1. Stallion Fertility.

The fertility of the stallion is really important when breeding from your mare but often gets overlooked when the choice of stallion is being made. Statistics on stallion fertility in the UK is very difficult to access as we have no central collection of data unless you are using a TB registered with Weatherby’s. Information such as conception rates would be really useful to have and some stallions do have fertility data available, care needs to be taken when analyzing the data as there are many factors that influence conception rates including mare factors, type of semen used and number of inseminations. I always advise asking the stallion owner/agent about the fertility of the stallion and discuss the results with your vet for an unbiased opinion. Getting in contact with other mare owners that have used the stallion will also be helpful, again remember there are many variables but if most of the mares got in foal after one or two inseminations then that will offer some peace of mind.

Learn from my mistake: I once chose a very popular eventing stallion to use on my event bred mare. Only after three attempts at chilled semen insemination did I find out that the stallion’s semen doesn’t respond well to the extender used when semen is chilled. I was unable to get my stud fee back and had to drive my mare seven hours to the stallion to be covered with fresh semen. Luckily she got in foal first time but the cost of the exercise was significantly more than I had anticipated and had I known the stallion was better with fresh semen I could have either taken her there straight away rather than wasting three cycles with chilled semen or chosen a different stallion.


  1. Age.

Age matters when it comes to fertility. Both age of the mare and age of the foal. As stallions get older their fertility will naturally decline. An experienced stallion owner/agent will try to manage this by reducing the number of coverings and looking for ways to try to maximize the stallions fertility. Older stallions are popular as they have had time to prove themselves as stallions and their progeny are of an age that their performance can be measured so as a mare owner you have more confidence that the future offspring will be successful than that of a young stallion. If you have a young mare that has bred foals before with no fertility problems then using an older stallion will most likely be okay but make sure you discuss with the stallion owner/agent what the best option would be as many older stallions may have frozen semen which may be higher quality than his current fresh/chilled semen. If on the other hand you have an older barren mare or a mare that has had difficulties getting in foal in the past then you would be wiser looking for a younger higher fertile stallion to give your mare the best possible chance of conceiving a foal.


  1. The type of semen.

There are three choices of semen used for artificial insemination; fresh, chilled and frozen. Some stallions will only be available by chilled, some only frozen and generally not many are available for fresh. For fresh semen you need to be able to insemination within two hours of collecting the semen, this limits the use to stallions based in the UK within a two hour drive, or that are based somewhere you can take your mare for AI.

Conception rates are generally better for fresh, then chilled then frozen but there are exceptions to this. Some stallions have exceptionally good frozen semen.

Fresh semen is ideal for mares that are difficult to get in foal, have fertility issues or have previously reacted to chilled semen.

The majority of AI we do is chilled semen and this is suitable for the majority of mares.

I generally don’t recommend frozen semen for maiden mares, older barren mares or mares that have proved difficult to get in foal in the past so if your mare falls under these categories look for a stallion that offers chilled or fresh. Frozen AI also comes at a higher cost as it is more intensive compared to chilled or fresh AI.


  1. Shipped semen.

Unless you are taking your mare away to stand at the stud you will need to have the semen delivered when ready to inseminate.

Fresh semen needs to be inseminated within two hours of collecting and most clients using fresh semen will collect the semen themselves and bring straight to the veterinary practice for insemination. Care needs to be taken that the environment during transport remains stable, no excessive heat, direct sunlight or rough transit. Ideally the semen should be stored in a polystyrene transport box. We have had an experience in the past where the semen was delivered to us in a carrier bag – needless to say the mare didn’t get in foal.

Question to ask: If you plan to use fresh semen ask how it will be prepared and given to you.

Chilled semen has opened up many possibilities for Stallions and we probably inseminate just as much semen from the EU as we do from the UK. Wherever semen is sent there is always the potential for problems during transit and we have most problems with chilled semen. Every year we have cases where semen gets lost in transit, arrives a day later than expected or where the semen arrives dead usually because it hasn’t stayed cool enough. 25% of semen fails to arrive to us before 12pm the day after collection.

Question to ask: Ask the stallion owner/agent what courier they use for semen and how reliable they have been in the past. Who is responsible for chasing the courier if the semen doesn’t arrive?Who will pay any costs of collection and delivery if the semen doesn’t arrive when expected?

Frozen semen removes some of the issues around transporting semen as it has to be delivered prior to the onset of the mares cycle so it is there ready. It must be transported by an experienced transport company and then stored correctly in liquid nitrogen when it arrives at its destination.


  1. Availability of Semen.

It never ceases to amaze me the number of times semen is requested for a mare and it is not available. Common reasons include the stallion is away competing or at a stallion parade, bank holidays affecting the courier companies, overbooking with too many mares needing semen on the same day or if the stallion operates a ballot system for semen. There is nothing more frustrating than preparing a mare perfectly for insemination and then not being able to get semen. Make sure you check prior to deciding on the stallion.

Questions to ask: Are there any dates the stallion will not be available? Are there any bank holidays that will affect delivery (particularly from the EU)? Is there a chance I will not get semen on my chosen day due to other mares or a ballot system?


  1. Experience of the stallion owner/ AI center

It is incredibly important that stallion semen is being handled and processed by experienced people. You need to find out where the stallion will be standing – if away at stud/AI center do your research and make sure it is a reputable experienced place. Speak to other mare owners and ask how their experience was. If the stallion is at home, how experienced is the owner? How long have they been providing semen from the stallion and what facilities do they have for collection and assessing semen prior to sending? Sadly there are no minimum standards for the quality of shipped semen but I expect all semen to have been checked prior to delivery and to arrive with paperwork detailing the quality of the ejaculate. I always check the sample under a microscope to make sure the quality hasn’t deteriorated during transit and is suitable for insemination.

There are some great AI centers and studs in the UK and for me I would only chose a stallion based at an experienced place.


  1.  Communication.

Most stallion owners/agents are great. They make my life so much easier, I’ll give them a call prior to the mares cycle, discuss the plan and try to give them as much notice of when we likely want the semen as possible. When we need it, we call them and the semen comes promptly when we need it, with all the appropriate paperwork and everything runs smoothly.

Unfortunately every year we have to deal with a stallion owner that frankly makes our job hard and getting the mare in foal extremely difficult. Communication is key. We have been left lingering for hours not knowing whether semen is going to be delivered and therefore not being able to administer the right drugs at the right times for a perfect ovulation. It really p*#ses me off and can be highly frustrating for everyone involved. There are some stallion owners/agents I would prefer not to deal with as I feel from past experience they are not as passionate about getting mares in foal as they should be, as we are, and it greatly reduces pregnancy rates.

My advice is, if you are having communication problems before you have paid your stud fee think very carefully about proceeding! It probably won’t get any better when they have your money. Most stallion owners/agents/studs should be more than willing to answer any questions you have and you want to feel they care about your mare and getting her in foal. Spring can be a busy time, and they will no doubt have many clients to get back to but if you’re made to feel like you’re not important look elsewhere!

One last note on communication – try to find out the exact situation or relationship between stallion owner/agent/stud/AI center. Sometimes it is very complicated. I have had clients thinking they are communicating with an owner when in fact it has been an agent. Many stallion owners are happy to chat about their stallions and answer questions, but if the stallion is standing at stud or an AI center we need to know who to communicate with when we need the semen.


  1. Paperwork.

This might seem like the most boring of my tips but every year at least one semen sample goes in the bin rather than in the mare due to lack of correct paperwork.

All semen should ideally come with paperwork giving information about  the quality of the semen at collection however this is not mandatory. In my experience UK studs and AI centers do this very well.

Any semen coming from outside the UK must BY LAW come with the original health papers for the stallion from the country of origin. It is against the law for a veterinary surgeon to inseminate a mare with semen that does not have the original health papers and therefore we are unable to do so. This puts us in a very difficult position when semen arrives and the mare is perfectly ready but there are no papers. She won’t wait another 24 hours so the cycle is wasted, plus all the costs involved.

Sadly, this happens every year because stallion owners/studs in the EU don’t send the correct paperwork. One stallion owner last year when I asked them to ensure the paperwork was sent with the semen (as it hadn’t been first time around) threatened not to send any semen at all. We don’t like working with stallion owners like this and I believe they give the industry a bad name.

If you’re choosing a stallion from abroad check with the agent that original health papers will definitely accompany the semen.


  1. Foaling terms.

There are many different terms available nowadays. With TB racehorses you generally pay your stud fee on 1st October if your mare scans in foal. Most sports horse stallion stud fees need to be paid upfront so it is important to know the terms. Here is an explanation:

NFFR – no foal free return

NFNF – no foal no fee

Some studs will specify the number of doses of chilled semen allowed (usually 3) but remember for each dose there will be a collection and courier cost. Make sure you double check how many doses you will be entitled to.

Frozen semen – check whether the fee is per dose and how many straws are included in one dose.

It is also worth checking if you can transfer to a different mare or if the terms can be carried over to the next season if you are trying late in the breeding season.

Make sure you read all the terms and conditions thoroughly.


Hopefully this blog has given you something to think about when choosing a stallion. Please let me know if you have any questions or what stallion you have decided!

Jenny xxx