1] Safety for all concerned. Stallions 'on a mission' can be a handful! Equally, not all mares like being covered and this can be dangerous for the handler as well as the stallion.
2] There is no need for the mare to travel. Not all horses travel well and some can be difficult to load. With AI distance becomes irrelevant and there are no livery fees to budget for.
3] Disease risks are much reduced.
4] Mares with back or hindquarter injuries can be put in foal by AI even when they can't be covered naturally.
5] As distance is no object, there is a greater choice of stallions.
6] The quality of the semen can be objectively measured.
1] Not all breed societies allow AI. Some allow AI if the mare and stallion are on the same premises at the time of collection and insemination.
2] Greater veterinary input is required to check the mare is ready to inseminate, especially if frozen semen is to be used. The cost of this should be discussed with your veterinary surgeon as many Practices have special 'packages' for studwork.
3] There is no regulatory standard for semen quality and unless the sample is accompanied by a certificate of quality assurance, the semen could be from a sub-fertile stallion or have been poorly assessed or processed.
Semen can be fresh, chilled or frozen.
is used when the stallion and mare are on the same premises and the insemination can take place immediately. It requires no special processing other than to keep it warm and out of the sunlight. If there is going to be any delay in inseminating the mare, the sample should be diluted as for chilled semen.
Chilled semen is the most commonly used as it is relatively easy to process and the sperm remain viable long enough to survive the transport time. A drop of semen from the filtered ejaculate is checked under the microscope to make sure the sperm are alive, very active, and have no significant abnormalities. A small sample is also checked to count the actual number of sperm that are present. The semen is then diluted with a special nutrient solution to keep them alive and stop them poisoning themselves with toxic waste products. The diluted sample is divided into 50ml doses, which are slowly chilled in special a container and packed ready for transport. The sample will remain viable for at least 48 hours and usually as long as 72 hours.
When ever possible we keep part of sample back to monitor its viability over several days.
The process for producing frozen semen is much more complex but frozen samples have the advantage that the semen can be collected from the stallion 'out of season' and then stored indefinitely.
Once a semen sample has been collected and evaluated, it is centrifuged to separate the sperm from the fluid layer and then sperm are re-suspended in a special fluid that protects them during the freezing process. After preparation, the sample is divided into insemination doses (straws) and then frozen in liquid nitrogen. Once frozen, the sample will last indefinitely and when required, the straws are dispatched in a special container that keeps the straws at -176C. Before long-term storage, one straw from every batch is thawed and quality-checked to make sure that the sample has survived the freezing process.