Dr Peter H Ward, senior veterinarian to the Royal Stables in Abu Dhabi, United Arab Emirates, on how to breed horses successfully.

Depending on the situation, the breeding stallion might be called on to cover a large book of mares in a short period of time so it is imperative that he be in peak condition. His health, fitness and fertility are all extremely important and can be influenced by management. A badly-managed stallion can have a marked effect on the conception rate.

In breeds where permitted, artificial insemination has helped to reduce the physical demands on a stallion, but management is still important for optimal semen quality. Management might vary depending on whether the stallion is to be used for AI or for natural cover but the basic principles are the same.

Breeding soundness examination: It is advisable to perform a breeding soundness examination before the start of the breeding season. This is more important in new stallions being used for stud as it will detect genetic faults, such as cryptorchidism, and an indication of semen quality. The stallion's libido and ability to mount are also important, factors which can be observed during this examination. It is important to ensure the stallion is free of transmissible venereal diseases, such as EVA (Equine Viral Arteritis). Although semen quality will give an indication of fertility, the ultimate test is the conception rate per cycle. In stallions that have previously been at stud this is generally known but can decrease with age. Semen quality and libido will give an indication of how many mares a stallion can service but this will vary depending on whether natural cover of AI is being used.

Nutrition: Breeding stallions should have a good body condition that should be assessed at regular intervals during the breeding season. A common mistake is to overfeed breeding stallions resulting in obesity, which in turn can affect libido and mating ability. Overfeeding of grain can predispose the horse to laminitis. Nutritional requirements for breeding stallions are probably very similar to maintenance level but stallions covering large books of mares might require slightly higher energy levels during the height of the breeding season. Good quality pastures and hay can supply most of the requirements and should form the bulk of the ration, but the addition of grain or a vitamin and mineral supplement may be necessary to correct any deficiencies.

A balanced diet is essential for efficient sperm production but there is no proven benefit to feed any nutrients in quantities above those recommended by the National Research Council. Where possible weighing of the stallion at regular intervals will show whether he is maintaining his optimal weight and is a useful aid in making any dietary adjustments.

Exercise: Nutrition and exercise go hand-in-hand as the more exercise the stallion is doing the higher will be his nutritional requirements. His diet will have to be adjusted according to the level of exercise. Exercise is not only necessary in order to maintain fitness but also to prevent boredom. Turn out in a paddock for as many hours as possible during the day is desirable and may be sufficient. However, should the stallion be inactive in the paddock, further exercise such as lunging or exercise on a horse walker might be necessary.

Vaccination and Deworming: During the breeding season stallions used for natural covering may come into contact with mares from other farms and areas so could potentially be exposed to a variety of infections. A vaccination programme should be drawn up by the farm's veterinarian as this may vary according to whichever diseases are prevalent in that particular area. It is advisable to try to administer vaccines more that 60 days before the start of the breeding season as any fever reaction can affect semen quality for some time.

It is recommended that stallions be dewormed every 60 days but his may vary from farm to farm depending on the conditions. Most of the commonly used anthelminitics appear to have little or no effect on fertility and are considered safe for use in breeding stallions. Other parasite control methods such as rotation and harrowing of paddocks or removal of droppings should also be employed.

Hoof Care: Hooves should be trimmed about every six weeks but this will vary according to conditions. Stallions with specific hoof problems may require shoeing or more frequent attention. However, it is preferable to leave them unshod whenever possible.

Dental Care: Routine dental examinations should be performed twice a year or whenever a problem is suspected. Once again horses with problems might require more frequent attention. Dental problems will make it more difficult to maintain a stallion in peak condition and can predispose to digestive upsets such as colic.

Training: It is preferable to have one person to handle the stallion so he can get to know his handler. At the same time the handler can become confident in handling the stallion and get to know of any problems or habits. The handler must be in full control of the stallion in the presence of a mare. Where necessary a chain shank over the bridge of the nose can be used and most stallions will eventually learn to respond to the handler's commands. New stallions can be allowed to tease a mare in oestrus over a teasing rail to familiarise him with this procedure. Whenever possible, stallions should be handled as gently as possible. Stallions can become unwilling to breed if they associate the event with pain or punishment.

Where possible, AI is the safest and most efficient way to utilise the stallion. Either an old quiet mare or a phantom can be used to collect the semen in an artificial vagina. The semen can then be inseminated directly into the mare, chilled or frozen for storage or shipping. This method is not only safer where maiden mares or mares that are not completely receptive to the stallion have to be covered, but is also enables a single ejaculate to be split into multiple doses. Depending on the quality of the semen several mares can be inseminated using a single ejaculate, which can considerable reduce the load on a stallion with a large book of mares. It can also considerably reduce bacterial contamination of the mare's uterus that normally takes place during natural cover. Another advantage is that it is easier and safer to transport chilled semen than it is to transport a mare and foal long distances. Most stallions can be taught to mount a phantom and where semen collection is being done on a large scale this would be the method of choice.

Breeding: Mares should be prepared for breeding by application of a tail bandage or wrap and washing of the perineal area. The stallion can then be brought into the presence of the mare and the erect penis gently washed with warm water and cotton wool. Most stallions will tolerate this well provided it is done gently. The penis should be dried as best as possible after washing and no soaps or disinfectants used as they may not only be spermicidal but may also interfere with the normal bacterial flora on the penis. Some stallions tend to bite the mare excessively during covering and in these cases it is advisable to use a leather pad over the whithers and neck of the mare. The mare must be adequately restrained to prevent injury to the stallion or to handling staff. The stallion is then brought up to breed the mare. The mare's tail should be moved out of the way and the stallion's penis may have to be guided into the vagina. Some stallions resent handling of the penis during covering and in these cases excessive handling should be avoided.

It is essential to make sure that ejaculation has taken place. Watch for the "flagging" movement of the tail which takes place during ejaculation. The stallion should then be allowed to lie on top of the mare until he is ready to dismount. At this stage the mare can be walked forward as the stallion dismounts. A sample of a few drops of semen can often be obtained from the stallion's penis as he dismounts and this can be used to verify the presence of sperm. The penis can then be rinsed with water and the stallion returned to his paddock or stable.

The frequency of covering or semen collection will depend on the book of mares the stallion has to service but will be limited by his libido and semen quality and output. Stallions used for natural cover can generally cover twice daily through the breeding season

Published: 28/01/2005