Mares...Anatomy,
A.I., and Troubleshooting
The North American Friesian Journal ~
October/November/December 2001
By Karen
Berk
|
 This is the first of a 4 part
series on reproductive techniques and effective management, by breeding
management consultant and CEO of Equine Reproduction Services, Karen Berk.
Karen has been breeding horses worldwide for 17 years. Her mobile lab
specializes in collecting stallions, semen evaluation, shipping and freezing.
In this installment she addresses "Mares, ...Anatomy, A.I. and
Troubleshooting".
I love horses! Any breed, age, gender, color or
discipline. I drove my parents crazy from the time I could talk. Foolishly,
they thought I would outgrow my fantasy. Instead it directed my life and became
my adult reality. I embraced my obsession with such tenacity that soon, riding,
showing, teaching and even judging were not enough. If I had been blessed with
artistic talent, I would have painted, drawn or sculpted endlessly in an effort
to recreate the essence of perfect beauty and harmony which is the perfect
horse. But no such talent did I possess.
Then, one day, by pure
accident, I stumbled on a stallion who took my breath away. I had never
considered owning a stallion, nor did I have the facility to keep one. An hour
later, that stallion was on his way home with me, and we began a journey. It is
now 17 years later, and my quest to create the perfect horse has taken me to
two Universities and three continents. I have sought out great breeders, and
studied legendary stallions to add to my pallet. I have also encountered many
like minds with the same goals and frustrations.
Creating true genetic
quality, both genotype and phenotype, it's not a toss of the dice. History has
shown us great and thoughtful horse breeders since the earliest written
records. Today we have understanding and technology available to the public
never before imagined. Stallion Collection, Shipped Chilled Semen, Artificial
Insemination, Cryopreservation, Embryo Transfer, Diagnostics, and on and on. We
have more colors on our pallet to create then ever. But with new techniques
come fear and misuse. Proper handling, collection, and evaluation, greatly
increase conception rates. Yet this has not been the case across the board, due
to shortcuts and greed.
How many of you on ordering shipped semen have
asked, how many progressively motile cells are being shipped per dose, that
ejaculate's concentration, motility and how they arrived at that dose? The
correct dosage to ship is one billion progressively motive cells, in a volume
of under 50 mls, if possible.
Many breeding centers will get call for 3
shipments, and regardless of correct dosage, extend the samples and just divide
it 3 ways and ship. If there were only 2 billion cells, no one gets a correct
dosage and conception changes are severely reduced. If only 2 had been sent,
the odds would have favored 2 satisfied customers and 2 foals next
season.
How about on the mare owner's end. Does your Vet or Tech use a
non spermicidal syringe, and evaluate the sample for viability after
insemination? As the recipient, consumer, of the semen, you have the right to
ask questions and receive a written evaluation of what you ordered. This should
be included in the package. If not, this constitutes mail fraud.
There
are stallions so potent that error seems not to be effect their success. But
this is the exception not the rule. When your dollars and cents are on the
line, you must remove the blindfold.
I do not believe, or even wish, we
will ever breed the perfect horse. He or she must remain in the fertile fields
of our own imaginations. It is there that we seek perfection that is individual
ourselves, and allows new ideas to benefit all. An educated breeder with a
great mare has the world at his/her fingertips. Remember, a foal takes 60 to
70% of it's dam's physical, genetic and athletic traits. The mare is by far the
most important contribution to the quality of the foal. A stallion that can
override the majority of a mare's genetic traits and replace them with his own
cells "prepotent", and is an exception rather than a rule. When this happens,
these great ones become the icons of their breed, and by all means should be
revered.
By finding a stallion that "nicks" with a mare, a good breeder
can produce a superior foal of championship potential year after year. A
stallion is always dependent on the quality of the mares booked to him.
Regardless of your affection for your mare, or perhaps she was a great buy, you
should take a hard look before you decide to breed.
First, pedigree: if all her well known ancestors or
champions are stallions, take another look. The most important line in a
pedigree is the "tail female lin". This is the bottom most line on the dam's
side of the pedigree. These are the strongest inheritable
genes.
Second, Age: Mares of more than 14 years of age have
significantly more inflammatory and degenerative changes of the uterus and less
contractile activity than younger mares. Physical conformation of the vulva may
make a "Caslick" procedure imperative. On the other side of the coin, clients
have brought me 2 and 3 year olds who were not reproductively mature,
regardless of cycling.
Third, General Health: A good nutritional
diet, suited to your mare's age and level of activity has been proven to be an
important contributor to conception and development of the fetus. Inoculation
and worming history, with continualtion throughout pregnancy should be routine.
Before breeding, a vet should perform a "breeding soundness" exam. Also, an
excellent idea before purchase.
Lastly, know or try to find out your
mare's past breeding history. Sub-fertility in mares is multifaceted. If I were
to attempt to group reasons, they would fall into 3 categories:
1) Age, 2)
Contamination and infection of the reproductive tract, 3) Malfunctioning of the
hormonal system. At times these will overlap.
The hormonal system of the
mare is perhaps her most important anatomical structure and the least
understood by the breeder. I would like to give you a quick review of what
happens when your mare's body prepares for pregnancy. First, the mares eyes
bring in added light which is recorded by the Pineal Gland which is located in
the tissues of the mid brain. It starts the reproductive cycle by producing
Gonadatrophic Releasing Hormone of GnRH.
When GnRH is secreted in the
proper amount, the Pituitary Gland located at the base of the brain is
stimulated. The Pituitary Gland then secrets 2 hormones that effect the
ovaries. The first is called Follicle Stimulating Hormone (FSH). It travels in
the bloodstream to the ovaries where it stimulates the development of one or
more follicles.
When the follicles reach 25 to 25 millimeters in
diameter, they secrete Estrogen. This hormone stimulates estrus (hear)
activity, causes relaxation of the cervix, stimulates contractions along the
mares reproductive tract, and signals the Pituitary Gland to stop producing FSH
and at the same time stimulates the second gonadatrophic hormone, Luteinizing
Hormone or LH. LH facilitates maturation of the growing, egg bearing follicle.
Ovulation occurs when the mature egg leaves the follicle and gegins
it's trip through the oviduct. Following ovulation, the estrogen level begins
to fall, and the remains of the ovulated follicle are converted to a form of
Corpus Luteum, or yellow body. These Luteal cells secrete the hormone
Progesterone. It is it's job to stop heating hormones, and to set the stage for
maintaing pregnancy. It subdues the contracting reproductive tract, and
tightens and closes the cervix. It also prohibits the secretion of FHS and LH
from the Pituitary, thereby putting the mare out of heat.
Obviously,
progesterone is a highly important hormone in maintaining pregnancy. In some
sub-fertile mares the correct amount of progesterone is not secreted. When this
happens, the other hormones swing into action and terminate the pregnancy,
bringing the mare back into heat.
Fortunately, progesterone levels can
be checked and monitored. Supplemental progesterone can be administered to the
mare throughout her pregnancy. Proper timing and appropriate levels of all
hormones are required to maintain a balance during breeding and pregnancy.
Wherever there is an imbalance, breeding problems will follow. If your vet has
found no physical, internal or conformational reason for a mare's
sub-fertility, ask him/her to do a homonal assay.
If
you order cooled semen, do not open the package/container without your Vet or
Tech. |
Perhaps your mare
is a nervous type. Or age, or physical disability makes travel undesirable or
simply the stallion of your choice is beyond your geographic reach. Transported
semen may be perfect for you. As we discussed earlier, properly timed and
executed, it has a very high percentage of conception on first cycle, with less
risk and expense. At the risk of repeating myself, the first step should not be
to call your vet for a breeding soundness exam. In the case of a mare that has
just foaled, you should be certain there were no tears or complications post
partem. Mares that have been open should have a culture AND cytology. A large
percentage of problem mares have clean cultures but will show up "dirty" on a
cytology. A cytology is an added test, inexpensive, taking 24 hours to
ascertain a wide range of infection and contamination.
Most mare owners
ask for a culture not realizing this is not an accurate picture, and many vets
do not recommend further tests if not asked. Another suggestion, particularly
on aged mares, is a uterine biopsy. A small sample is excised, cultured, and
gives a very good picture of the uterus. This, coupled with a sonogram, will
arm you with enough information to make an educated decision as to go on with
the further expense of contracting a stallion and transporting
semen.
Next step, your mare comes into heat. Once again, contact your
vet. He/She will want to palpate your mare on or about day 3 to assess her
follicle and coordinate with the stallion manager. You do not want to order
semen too early. Semen should arrive no earlier then 24 hours prior to
ovulation, and not more then 6 hours after. Keeping in mind, mares ovulate
between 4 in the morning and 10 AM. If your shipment arrives and your vet says
she has just ovulated, do not panic. This is still good timing. The egg will
rest in the Ova Fossa for a few days. This is the site of conception. If you
inseminate too early, the sperm arrives but are weakened by the time the egg
does.
Your Vet or A.I. Technician should work closely with the stallion
manager to coordinate timing of shipment and ovulation. When the shipment
arrives, do not open the container. I strongly suggest your vet or tech have a
microscope to check the semen AFTER insemination. Do not warm the packet or let
it come to room temperature. The mare's body is the perfect incubator. Do not
use more than one dose if you think she is going out of heat and you don't want
to waste any. The calculated dose is sufficient, and according to the studies
at Colorado State University, inseminating with more than 50 mls. is actually
detrimental to conception.
Do ask your vet or tech to use a
non-spermicidal syringe. These are all plastic. The black tips on regular
syringes are spermicidal to many stallions semen. Do be sure to wash and dry
your mare's perinatal area thoroughly with warm water and mild soap, making
sure there is no residue remaining. Towel dry with clean, white paper
toweling.
The dose will be drawn into a syringe, (or in the case of
Equine Express container being used, it is already in the proper syringe), a
pipette attached. It is then inserted vaginally, passing through the soft and
open cervix. The procedure is quick. Since the semen is placed in the uterus,
you don't have to worry about "dumping" the inseminate, as you with natural
cover.
If you have covered your basics and followed a sound reproductive
program, the result will be a win, win situation for all the players and you
will have the quality of foal to be contender. Whether your goal is the show
ring, trail, or adding another beloved family member, breeding success = good
horse cent$.
Next monthh is the stallion issue and we will address the
subject of the breeding stallion, anatomy, semen evaluation and the effect of
adding artificial light for a stallion's libido and potency. I am always
available to answer questions at Equine Reproduction Services · 504 SE
35th Ave · Ocala, Florida 34471 ·
mailto:ERSmobileAiLab@aol.com |
|
|
