Breeding the mare with cooled semen
When the cooled semen arrives for insemination of the mare, current recommendations are to:
- Prepare the mare for breeding. The mare should be adequately restrained with her tail wrapped and held to the side. The
perineal area is thoroughly scrubbed and rinsed, paying particular attention to the vulva. Any dirt or fecal material within
the caudal vestibule should be removed during the washing process to prevent contamination of the anterior reproductive tract
during insemination. Two to three scrubs with a non-irritating soap (e.g., Ivory Soap) or a surgical scrub are recommended,
followed by thorough rinsing to eliminate residual soap that may be spermicidal or irritating to mucous membranes. The perineal
and vulvar area should be thoroughly dried prior to breeding.
- Open the shipping container and confirm the identity of the stallion using the accompanying form. Remove the chilled semen,
gently mix it, aspirate the semen into a syringe, and attach an insemination pipette. Sterile nontoxic disposable equipment
is recommended for AI procedures. Syringes with non-spermicidal, plastic plungers (Air-tite, Vineland, NJ) are preferable
for AI since rubber plungers may possess spermicidal properties.
- Inseminate the semen into the uterus of the mare. To inseminate the mare, a sterile shoulder-length plastic sleeve is
first placed over the arm used for insemination. The tip of a 20 to 22-inch insemination pipette is then positioned in the
cupped hand and a small amount of sterile, non-spermicidal lubricant is applied to the back of the hand. Just prior to passing
the hand into the cranial vaginal vault a syringe containing extended semen is attached to the insemination pipette then gently
press the plunger on the syringe until the extended semen fills the pipette. Then the covered hand and insemination pipette
are passed into the cranial vaginal vault where the index finger identifies and penetrates the cervix. The insemination pipette
is then advanced through the cervix to the mid-body of the uterus. Slowly deposit the entire syringe of extended semen
into the uterine lumen. Remove the syringe while leaving the pipette in the uterus draw approximately 5 mL of air into the
syringe, re-attach the syringe to the pippette and plunge the remaining extended semen left in the pipette into the uterus...
(Note:The volume of the pipette is approximately 5-6 mL & you do not want to waste 25% of your breeding dose)
An alternate, but equally satisfactory, method of insemination is to pass the insemination pipette through the cervix into
the body of the uterus using a lighted speculum preplaced in the vagina.
- A small aliquot of the extended semen should be kept and warmed to 37oC, and sperm motility should be assessed and recorded
for quality control purposes. If sperm motility is poor, inquiries can be made in an effort to determine if this was an unexpected
problem. It is sometimes helpful to prepare a specimen for assessment of sperm morphology. A high percentage of morphologically
abnormal sperm would be expected to yield a low precentage of progressively motile sperm following cooling. If sperm motility
is consistently poor and the mare fails to conceive on repeated breedings, it is possible the stallion is incapable of producing
sperm which survive the cooling/transportation process. Alternatively, use of a different semen extender or dilution ratio
may prove beneficial to semen harvested from that particular stallion.
Overseas workers often recommend warming the cooled semen to body temperature prior to insemination of the mare. In the
U.S., the cooled semen is usually inseminated directly into the uterus as soon as possible after opening the shipping container.
Since no detrimental effects on pregnancy rate have yet been determined by inseminating mares with cooled semen, at present
we see no reason to prewarm the cooled semen prior to insemination unless a cream-gel extender is used. This extender forms
a gel at refrigerated temperature, so it must be warmed prior to insemination. The packaged sample can be placed in an incubator
or waterbath preset at 37-38oC. It is important to avoid contamination of the extended semen with water when warming the sample
in a waterbath.
It has become common practice for many stallion owners/managers to prepare two bags (insemination doses) of extended semen
for shipment - one to be used for an initial insemination upon arrival, and one to be held for insemination again the next
day. For many stallions, the longer the semen is held at refrigerated temperature, the poorer sperm motility becomes. However,
if semen is to be held for breeding again the next day, precautions should be taken to maintain the cooled semen at 4-6oC
until the time of the second insemination. Once a shipping container is opened for the first breeding, temperature of the
semen left in the container is likely to rise above 10oC, causing premature sperm death. The remaining semen dose can be immediately
placed in an insulated box within a refigerator (4-6oC) - until it is to be opened for breeding the next day. This would be
especially critical for semen cooled in some "disposable" type shipping containers which may only maintain semen at < 10oC
for 27.5 to 33.5 hours.
Natural mating: In most horse breeds, 50 - 60% of mares conceive in each oestrous cycle, by the end of the
breeding season 89% of mares are pregnant and only 79% of mares go on to produce a live foal. In Central Wisconsin the average
mares best and most breedable time is the third week in April.
Fresh / chilled semen: When fresh or good quality chilled semen is used for artificial insemination (AI) we
can expect slightly higher (5 – 10%) more per cycle pregnancy rates compared with natural mating. It normally takes
1 – 2 cycles for a fertile mare to conceive.
A note about using drugs/hormones to force ovulation:
We only use Deserline and only on incoming semen. Giving mares drugs
unnecessarily can some times cause you more problems than are warranted. However with incoming and not knowing the quality
of the semen we just don't take any chances.
Even though Deserline is very expensive and you can only use it one time in a
season on a mare, we have had excellent results. With HCG or GNRH Follicle release time is really all over the
map where as with Deserline we know it will drop in 36 hours on the nose if the Follicle is between 33mm and 40mm if it is
much bigger it might drop all on its own and if it is smaller the chances of settling is not good.
Note: A lot of people do it but giving Follicle release shots without Ultra Sounding
is like trying to hit the pot in the middle of the night, more than likely you will miss more than you hit.
An added opinion is:
Most vets will do what
they know and most mare owners live by what their vet suggest, which they should. They are the ones taking
care of their mares and breeding them.
We should not be using drugs any more than we have to... The natural breeding
cycle and ovulation is the absolute best way to go... There are many reasons to administer drugs to mares and here are
a couple examples...
1. Mare won't go out of heat and we need that follcile to rupture, 3
weeks in heat and still no rupture. Her settling on this heat cycle is rare but my vet said try it. (Once again
I listen to my vet).
2. Mare needs the shot because we will have to drug her to do AI on
her. She freaks out in the stock and is very dangerous. Otherwise we will have to do live
cover and that is very risky as well.
every breeding is a different situation and we just have to adjust, be flexible and do our best… I do know that we get
better every time we tackle a problem and we wouldn’t be where we are today if it wasn’t for loving
these animals and enjoying what we do… So, a big thank you to all of the people that help us along the way... Without
them we wouldn't be where we are today...
Examination for pregnancy
We recommend the mare bred with transported cooled semen be examined for pregnancy using transrectal ultrasound at 14-15
days postovulation. This enables early detection of a pregnancy that is normal for stage of development, allows early detection
of twins before they become fixed in the uterus, and provides time for rebreeding during the same estrus if the mare failed
to become pregnant.