A3o—Lancaster Farming, Saturday, June 4,1983
BY TRISH WILLIAMS
QUAKRYVJLLE Embryo
transfer (ET) certainly is not a
new concept. The first successful
embryo transfer was recorded in
1890 at the University of Cam
bridge when two fertilized eggs
were obtained from an Angora doe
rabbit and transferred into a
Belgian hare doe. But it wasn’t
until the mid-1960’s that surgical
embryo transfer became practical
in cattle.
Research findings over the last
twenty years have rapidly ad
vanced the applications of ET.
This rapid progress in research is
due in part to interest in exotic beef
breeds during the ‘6o’s, and by
purebred dairy breeders, but just
as important in obtaining funding
for research was the interest in
genetic engineering for application
in human medicine.
In recent years we have been
hearing about laboratory research
being conducted on sexing,
freezing and splitting embryos.
These techniques have become
refined enough that they are now
being done in the field by a few of
the more progressive'
veterinarians.
Carl G. Troop, V.M.D. is one
such veterinarian. Dr. Troop who
has been performing embryo
transfers for four years, has
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Donors are given a spinal nerve block before flushing to
relax them. This donor, Galena, is so relaxed that she is
eating hay while Dr. Troop performs the flush.
Fluid for flushing is gravity fed from 36 inches above the
uterus, through the uterus and is collect by Ms. Lowe in a
Taking non-surgical ET to the farm
refined his technique for non
surgical ET, and has been using
only the non-surgical method for
ET for the past two years.
Troop works hard at keeping
abreast with the latest advances in
ET. As a member of the Embryo
Transfer Society he attended its
annual meeting and a workshop
this winter in Denver, Colorado.
Troop learned how to freeze em
bryos at the workshop. He also
works closely with researchers at
the University of Pennsylvania’s
New Bolten Center in Kennett
Square.
Troop owns his own dairy herd,
this gives him the ability to
practice and master new
techniques on his own animals
before offering the service com
mercially. Troop’s herd is also
used by researchers at Penn,
currently Troop has two recipient
heifers who were implanted at
Penn and are pregnant with test
lube calves. When these two calves
are bom later this summer they
will be second and third calves in
the world to be bom from an in
vitro fertilization {conceived in a
test tube). The first calf bom from
an in vitro fertilization is at the
New Bolton Center.
Troop credits progressive
dairymen with much of the recent
success of appplication of new
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techniques in the field. The
dairymen are responsible for
synchronizing recipients with the
donor, and maintaining accurate
records.
The estrous cycle ot donors must
be accurately delected and
characterized to get the best
results from superovulation
treatments. It is best to observe
two normal heats postpartum
before starting to treat a cow with
prostoglandins tor superovulation.
Heat detection is also important
in recipient heifers. Kecipients
must be in estrus within one day,
plus or minus, of the donor for a
high success rate. To synchronize
recipients with the donor, Troop
gives the dairymen the necessary
drugs and a ‘Donor and recipient
programming schedule’ to follow.
The schedule gives a tune table for
the drug treatments for both
donors and recipients and in
dicates when they should show
signs of estrus.
Troop recommends breeding the
donor early in standing heat and
again in about 18 hours. This is
because when the donor is
superovulated the ova are released
from the ovary over a period of
time.
The synchronization of the
donors and the recipients is the
same for this non-surgicai transfer
technique as is used for surgically
performed J£T.
Troop uses the' non-surgicai
procedure for recovering the
fertilized embryos six to eight days
after the donor is bred. Doreen
Lowe, lab technician and transfer
assistant, helps with the
procedure.
After the flushing procedure has
been performed the nutrient
solution containing the embryos is
taken back to the lab at Pennstar.
The nutrient solution is allowed to
sit for about a half-hour, to allow
the embryos to settle to the bottom
of the flask. Doreen Lowe and
Nancy Hoffer then start the search
for the embryos by examing the
solution under stereo-variable
microscopes. This job takes a
trained eye and a great deal of
patience. Once the embryos are
found under the microscope they
must be isolated and classified,
then with sterile technique the
embryo is manipulated into
another medium tor transfer into
the recipient.
After the number of fertilized
embryos suitable tor transfer has
been established Troop nolififies
the dairymen how many recipient
heifers are needed tor the transfer.
Now, with tiie facilities to freeze
embryos it is not necessary to
transfer all the embryos fresh.
Like semen, the embryos can be
frozen in a liquid nitrogen lank tor
later transfer.
The synchronized recipient
heiters are brought to Fennstar the
same day and implanted non
surgically with the embryos and
sent back to the tarm immediately.
Recipient heiters are prepared
tor the transfer the same way the
donor was prepared tor flushing.
The tailhead is clipped and the
vulva area is scrubbed. A spinal
nerve block is given in the
tailhead. Troop checks the heiter
tor presence ot a corpus luteum to
maintain the pregnancy.
The non-surgical method tor
embryo transfer is very similar to
the procedure use in artificial
insemination. The embryo is
drawn into a French straw like
those used in artificial in
semination. The loaded straw is
pul into an inseminating gun, the
lips ot the vulva are parted by an
assistant so that Troop does not
carry any contamination into the
uterus on the inseminating gun.
Troop manipulates the in
seminating gun through the cervix
into the horn ot the uterus that is on
the same side as the corpus
luteuin.
Stereo microscopes, Doreen Lowe, left, and Nancy Hoffer
examine the fluid flushed from the donor cow for embryos.
Embryos are implanted in the recipient heifers by a method
very similar to artificial insemination, using no surgery.
"Placement of the embryo in the
uterine hom is very critical,” said
Troop. “It took me alot of practice
on my own herd to be able to place
the embryo accurately and con
sistently. Heifers often have a very
tight cervix at this stage in the
estrus cycle. That can make
passing the inseminating gun
through the cervix difficult. ’'
As soon as resistance in met in
the uterine horn the embryo is
expelled and the gun is removed.
This method of transfer requires
Ms. Lowe first locates the tiny embryo under the
microscope, then draws it into a glass straw for implanting.
a great deal ot manual dexterity.
The endometrial lining of the
uterus is very fragile and ruptures
easily.
it takes Troop about 15 to 20
minutes to do the transfer. Then
the heifers are loaded back in the
trailer and shipped back to the
tarm. Flushing the donor, isolating
the embryos and transfering them
into recipient heifers can all be
done within a matter of a several
hours, all without a single cut of
the scalpel.
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