At West Kington Stud, we are often asked about the optimum number of sperm in a ‘dose’ of semen, to achieve a successful pregnancy. In this article, Chris Shepherd BVSc MRCVS, from B&W Equine Vets, shares his insights into this fascinating subject.

The Journey of Spermatozoa through the Equine Reproductive Tract

The hazardous journey for spermatozoa through the mare’s reproductive tract means that a huge excess must be deposited into the uterus at the time of insemination or covering. A fertile stallion can produce anywhere between 5 billion and 25 billion spermatozoa at ejaculation. Not all will be live, and not all the live ones will be viable but, bearing in mind only one is necessary for fertilisation, there are plenty to spare. 

At a natural cover, the whole ejaculate (consisting of the spermatozoa and the seminal plasma produced from the accessory sex glands) is deposited directly into the uterus. If the mare is artificially inseminated, we are able to decide which parts of the ejaculate and exactly how many live spermatozoa are deposited into the uterus. Most ejaculates from a fertile stallion will provide sufficient spermatozoa to inseminate several mares, if they are available and ready at the time. 

From Ejaculation to Insemination: Understanding Spermatozoa Numbers

There is considerable debate as to how many live spermatozoa should be inseminated for that mare to have a reasonable chance of conceiving. Traditionally, it has always been accepted that 500 million is a reasonable figure. A stallion that ejaculates 20 billion spermatozoa that has 75% alive and viable would therefore be able to provide enough doses to inseminate 30 mares. However, 500 million may be a generous estimate and the required figure may be closer to 250 million. In reality, the fertility of the mare and the method of insemination will have a large influence on the number of spermatozoa that have to be inseminated. Continue reading

As 2023 draws to a close, we have taken a little time to look back on the year at West Kington Stud. Despite some interesting challenges from the British weather, the breeding season proved to be our busiest yet, with the safe arrival of 50 beautiful foals onsite. In addition to the foalings, we had a good number of both maiden and experienced mares through for successful insemination with Fresh, Chilled & Frozen semen & for Embryo Transfer, and we look forward to hearing about their progress in the coming months.

Our stallion line-up for 2023 saw the welcome return of our wonderful old friend, Billy Congo from The Billy Stud. Congo was used on some high class mares, with breeders recognising his exceptional performance record and the success of his progeny. The Billy Stud also sent us a very exciting 3yo stallion named Billy Reflection. This son of Grandorado TN is a striking, modern stamp of a sport horse who we are sure will be very popular as a sire in the future.

We were also joined by John Chambers’ lovely Thoroughbred, Ansiei, for the first time. With his progeny already competing internationally up to 4* level in Ireland, Ansiei is an exciting choice for eventing breeders and was a very welcome addition to our line-up. Continue reading

Our annual Christmas missive comes at the end of very long and busy season, in fact the last inmates of the Stallion Centre for collecting for worldwide export have only just left us! It was an early start to the stud season as well, with mares arriving to foal down and for AI from mid-March. A busy summer followed, and the vagaries of the British weather were challenging to say the least, with many mares cycling abnormally, which, as we are sure many vets will agree, was an issue throughout much of the UK.

The weather also played a part in our annual Open Day on the eve of Badminton Horse Trials at the beginning of May – we had changed the format from afternoon to evening, and it was just as well we did as the afternoon was unseasonably warm and would have been hard on the stallions attending. As usual, this event was well supported by many owners and friends.

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2018 has been busy and successful year – both on the stud and stallion centre.

CEVIN Z had a very busy season and it is now recognised as one of the best sportshorse stallions in the UK producing international show-jumpers as well as eventers at all levels for all breeders. He coped very well and achieved a great conception rate. CHILLI MORNING had a good this season and he has settled in to the daily life of being a stud stallion – as long as he has his daily hacks. HANDASSA (Shadwell Stud) had a good first season at Stud – his bookings for 2019 are impressive!! WELTON DOUBLE CRACKER and WINDSOR HEIGHTS continue to produce successful
offspring. It has been fun hearing about their varied roles as eventers, show horses and general multi- purpose horses and ponies from their various owners. LEGRANDE spent 6 weeks at stud (as a break from his competitive career representing the UAE).

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2017 has been busy and successful year – both on the stud and stallion centre. In January Tessa spent a few weeks in Kenya and made a useful contact with Venetia Philipps (a protégé of Professor Twink Allen). As a result we are now exporting frozen semen to Kenya. Irish Draught, Connemara and New Forest stallions seem the most popular. With the first 6 mares in foal with one insemination each, Venetia appears to be doing a great job!

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We were very proud to be involved with the production of the Story of the Caspian Horse at HOYS 2017 last week. The pure bred Caspian Stallion Hendon Troy, owned by Fleur Morfoot and ridden by our own Jess Lee was a real superstar. Only brought in from the field a few weeks ago, Troy came to WKS to be schooled for his role as lead horse in a magnificent display which was performed 7 times during the event, including the grand finale on Sunday night. A huge congratulations to all concerned and thanks to our many supporters.

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