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Breeding Season Artificial Insemination (AI) - Pregnancy tests - Barren Mares - Stallion Collection Kessock Equine Vets offers a full equine breeding service including chilled and frozen artificial insemination, semen collection and investigation and treatment of breeding problems. Artificial insemination packages are available for 2008, please call our office for details. During the breeding season, mares show repeated oestrous cycles of about 21-22 days in length; this is usually made up of about 5 days in-season followed by about 16 days of 'dioestrous' when she is not responsive to the stallion. When the mare is in-season (on heat) she develops a collection of follicles and usually one of these follicles goes on to mature and releases an egg from the ovary (ovulation). During dioestrous a structure known as a corpus luteum (known usually as a CL) predominates and this releases progesterone hormone ensuring that the mare rejects the stallion. Ideally, insemination with chilled semen or natural covering should take place in the 24 hours before ovulation. There are essentially two ways of breeding your mare : natural service or artificial insemination (AI). Artificial insemination This is a useful way of breeding your mare, without the inconvenience of moving your mare to stud, particularly if the stallion is far away. This procedure should not be seen as a cheap alternative to natural covering but there are reduced costs such as travelling your mare, particularly as we live in the Highlands. Artificial insemination utilises either fresh or preserved semen. Fresh semen is really only used on studs or where the mare is very close to the stallion, i.e. the semen is collected from the stallion and immediately inseminated into the mare. Most AI uses either chilled or frozen semen, which means that rather than transporting your mare to the stallion, the semen is delivered to you. The obvious advantages to this are reduced travelling and livery costs whilst your mare is at the stud, as well as reduced risk of injury to your mare and to the stallion. You can also choose a stallion from anywhere in the UK if you are using chilled semen and anywhere in the world if you choose frozen semen. In addition, there is generally a reduced risk of venereal disease and the mare has a higher chance of breeding successfully, particularly where she has had problems breeding in the past. The main disadvantages for horse owners is that, with your mare at home, you will be responsible for ordering the semen and bringing your mare indoors for scanning and other gynaecological procedures. You must have suitable facilities or you must move your mare to a yard where there is staff and stabling for your mare. You must also be able to tell when your mare is in-season. A lot of mares will show to a gelding or other mares, but many mares are silent and in the absence of a stallion it can be very difficult to know what stage of their cycle they are at. Even using repeat ultrasound examinations, these mares can be very difficult to deal with and you should endeavour to find a way of teasing your mare. The onus is on you to do the work that would otherwise be done by a groom on a stud and a successful breeding programme is dependant on good communication between yourself, your vet and the stud. Chilled Semen The most popular form of preserving semen is chilling. In this way the sperm are cooled down and a semen extender is added to help preserve the sperm for their journey. The semen is then transported to your mare in a cool box, of which there are a range of different types from the expensive Equitainer to relatively inexpensive polystyrene boxes. Good quality sperm will normally survive this process for insemination the next day and in some cases can last 48 hours or longer in this fashion. The container is treated like any other package and delivered overnight by a courier such as ParcelForce (www.parcelforce.com) You must check with the stud that they will arrange delivery for you and that the courier will deliver to where you live. For example, some couriers will not guarantee overnight delivery to an IV postcode and some will not deliver on a Saturday. What is vitally important is that the mare is inseminated at the correct time and with chilled semen this is just before ovulation. We will normally like to examine your mare on the 2nd day of her heat (oestrous) and again on the third day, depending on what we find when examining her ovaries. When she has a 35-37mm follicle and other signs of impending ovulation such as uterine oedema, we will ask you to order the semen for the next day. When the semen arrives, we will come to you, inseminate the mare and then re-examine her the following day to ensure that she has ovulated and that she hasn't developed any inflammation in her womb. We often administer medicines to encourage her to ovulate and if there is any chance that she has developed a post-insemination infection, we will treat that too, in order to improve the chances of her conceiving. We normally schedule a 14 day pregnancy check and this is included in our fees, but we strongly advise a further check before day 35, to check the developing foal's health and to confirm that there is indeed only one foal present. Frozen Semen Stallion sperm do not survive the freezing and thawing process as well as in other species. Those sperm that do survive are very fragile and insemination should occur as close to ovulation as possible. This may mean repeated ultrasound examinations as often as every 6 hours, even during the night, as well as an overall reduced fertility rate. We don't recommend the use of frozen semen in mares which have had problems conceiving in the past or if you are new to horse breeding. Our protocol for the insemination of mares with frozen semen is that we examine the mare on the 2nd or 3rd day of oestrous (in-heat) and re-examine her every 24 hours until there is a 35-37mm follicle. At this stage we administer an ovuplant hormone and re-examine her after 24 hours. This is followed by 2 examinations at 12 hour intervals and insemination and wash-outs when required. This is adapted from the breeding programme used at Twemlows stud in Shropshire where the owners quote a success rate of 50% per cycle and an overall pregnancy rate of approximately 80% after 3 cycles. Pregnancy Tests The most effective way of detecting pregnancy is by ultrasound scanning which checks the health of the foal as well as excluding the possibility of twins. Pregnancy can also be diagnosed by a blood test between days 60 and 90 for a hormone called PMSG, although this is not as accurate as a blood test for oestrogen from about day 100. Oestrogen can also be picked up in urine and dung from about day 150 onwards and this too, is an accurate test of pregnancy. Barren Mares Mares which have been barren, i.e. have failed to conceive in previous years should be examined thoroughly at the start of the breeding season. There can be many reasons why a mare has failed to conceive but the most common cause of poor fertility in mares is low grade endometritis which an inflammatory reaction or infection in the lining of the womb. This infection doesn't necessarily need antibiotic treatment because it is often caused by a failure of the mare's clearing mechanism, but antibiotics are used in some instances. It can be very useful to perform a small biopsy of the lining of the womb, which would let you know whether the mare has any chance of breeding, or what treatments are necessary to help her. The biopsies are safe and it is vital that the biopsy samples are sent to laboratories where they can be examined by vets who specialise in equine pathology. Stallion Collection Most stallions can be trained to ejaculate into an artificial vagina and if the semen is handled and transported correctly then sending semen can be a useful way of increasing your stallion's progeny and providing you with additional income. At the start of the breeding season we recommend that a test ejaculate is taken to assess the stallion's likely fertility and we insist that he is tested free of venereal diseases as dictated by the HBLB codes of practice. For a stallion that has not been used for AI before, we take the test semen sample and extend it with a range of semen extenders, then chill the semen before testing it daily to assess which extender is best for him and how long we should expect his semen to last. By doing this you can be sure in the knowledge that he is fertile and that his semen does chill well, which prevents mare owners claiming that it's the stallion's fault! We can collect, evaluate, preserve and arrange transportation of semen from stallions within our geographical area. If you live outside these areas, please contact us in advance to discuss your requirements. |
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