What
is Artificial Insemination?
Artificial insemination
(AI) is the process of introducing semen from a donor stallion into a mare when
she is in estrus by means other than sexual intercourse to achieve pregnancy.
The process has been used in livestock for decades, especially cattle, but more
recently the practice has become more utilized in horses. Donor semen can be
fresh, chilled, or frozen and is administered through a pipette vaginally by a
trained professional, usually a veterinarian. Some horse breed associations,
notably thoroughbred breed associations, do not allow AI offspring as part of
their registry, and others require a veterinarian perform and certify the
procedure. The process has good success; if performed by a trained
professional, using viable semen on a fertile mare, the success rate approaches
that for natural breeding.
Artificial
Insemination Procedure in Horses
AI may be performed at
the mare's home site or at a breeding facility. The advantage of a home site is
that the mare is more relaxed and less stressed, however, experienced personnel
and handling facilities are present at a breeding facility. Semen may be fresh,
chilled or frozen. Fresh semen has the highest fertility, and is least
expensive, however the mare and stallion must be at the same facility as semen
must be used immediately. Chilled semen can be transported, if used within 24
hours, and is viable for another 24 to 48 hours once the mare is inseminated. A
tight timeline requires coordination of shipping and performance of the
procedure, and ovulation by the mare. Frozen semen is preserved with liquid
nitrogen and can be stored for years then transported and used when convenient
to the mare's estrus and ovulation cycle. Frozen semen is the most expensive
and has the least successful insemination rate.
To ensure that the mare
is in estrus, and ready to ovulate, an ultrasound can be performed regularly to
monitor when the ovarian follicle reaches 35mm and the mare shows signs of heat
cycle. When this occurs, AI with fresh or chilled semen should be performed on
the mare every 48 hours until ovulation occurs. Some veterinarians induce
ovulation with luteinizing hormone injections, which will reduce the number of
AI attempts required until ovulation occurs. Frozen semen is used immediately
after ovulation occurs, (within 6 hours), for best results. This requires
ultrasounds to be conducted more frequently to “catch” ovulation as it occurs.
·
In order to perform AI, the mare is secured in
a palpation chute, if available, and her tail is wrapped and moved to the side
to avoid contamination and interference.
·
The vaginal area is cleaned; soap and
detergents are sometimes avoided so as not to remove natural flora present.
·
Semen is drawn into an insemination
syringe or pipette. To use frozen semen, the straw containing semen is
withdrawn from the liquid nitrogen tank and immediately immersed in a water
bath to raise it to body temperature and then drawn into an insemination syringe
for use. Sterile procedures must be maintained throughout this process.
·
A sterile lubricated glove is utilized,
and the inseminator puts an arm into the vagina and identifies the cervix and
the depression indicating the opening to the uterus. During ovulation, the
cervix is more relaxed.
·
A gloved finger is placed over the
syringe or pipette with semen and is introduced into the vagina and into the
depression in the centre of the cervix. The pipette is then introduced, gently
so as not to cause any damage, still covered by a finger, into the cervix. When
it is about 1 inch into the uterus the plunger is depressed and semen released
into the uterus. The arm and pipette are slowly removed.
Efficacy
of Artificial Insemination in Horses
Artificial insemination can be as efficient as
natural breeding if estrus is followed closely, ultrasound is employed, and an
experienced inseminator or veterinarian performs the procedure using controlled
procedures. Fresh and chilled semen is associated with better results than
frozen semen, however, requires careful coordination and timing or that both
animals be present at the same location.
Artificial
Insemination Recovery in Horses
The mare should be checked for pregnancy after AI
procedure, within 14 to 16 days, so that if she is not impregnated AI can be
attempted again at the next ovulation cycle.
Horse
Artificial Insemination Considerations
Success of AI varies depending on the quality of
semen, whether fresh or frozen semen is used, the fertility of the mare, and
several other procedural factors. The process can be expensive and yield no
results. However, when ultrasound, appropriate procedures, and verified semen
is used, results can be good. Success with older maiden mares is not as good as
in broodmares and young horses. Bacterial infection is a risk and sterile
procedures will mitigate this. AI also mitigates disease by preventing horses
from stress and exposure to disease during traveling and at unfamiliar facilities.
Venereal disease is less likely due to the concentration of semen and extenders
used in the process.
Artificial
Insemination Prevention in Horses
AI is most commonly used because of the
impracticality of both horses being colocated for breeding purposes, however,
if a mare or stallion is injured preventing natural breeding, AI may be
utilized. Preventing injury in breeding animals will therefore eliminate the
need to perform AI as a means of circumventing injuries that make natural
breeding risky.
AI
may also be used where the behavioral or temperament of the horses involved
makes natural breeding risky due to the potential for injury to occur during
the process. In this case, AI may be a means of preventing injury.
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