Embryo transfer involves removing embryos from female cattle of superior genetics and implanting them into recipient females. This allows one donor cow to produce many offspring, improving herd genetics faster. The process begins by synchronizing donor and recipient estrous cycles then flushing embryos from the donor 7 days after breeding. Embryos are examined before transferring viable ones into recipients. While expensive, embryo transfer can increase genetic gains if used with donor cows having desirable traits.

1. Embryo Transfer in Cattle

2. Introduction
 Embryo Transfer is a expensive procedure,
costing around $300 for each flush and
approximately $270 for each calf born. Not
including the cost of the semen.
 Students should understand that ET is a
complicated procedure with a fairly high
difficulty level.
 ET should only be performed by trained
professionals.

3. Objectives
 Explain the benefits of embryo transfer.
 The impact that embryo transfer has on the
livestock industry.

4. Reproductive Anatomy

5. What is an Embryo?
 An embryo is an
egg that has already
been fertilized by a
sperm cell.
 It is an organism in
the earliest stage of
development.

6. What is Embryo Transfer?
 ET involves the removal of an embryo from
a female of superior genetics and the
placement of the embryo into the
reproductive tract of a female of average
genetics.

7. What is the Goal of Embryo
Transfer?
The goal of ET is to obtain the
maximum number of genetically
superior embryos in a minimum
amount of time.

8. Benefits of Embryo Transfer
 Traditionally, cows
produce only one
calf per year. ET
allows the
production of many
offspring within a
year from a single
cow.

9. Benefits (continued)
 ET can increase the genetic potential of a
herd in a relatively short period of time.
 ET can increase milk production in dairy
herds.
 ET can increase weaning weights in beef
and dairy herds.

10. Benefits (continued)
 ET allows other producers to take
advantage of superior genetics because
frozen embryos can be shipped almost
anywhere.
 ET preserves superior genetics for future
generations due to embryo freezing.

11. The Process of Embryo Transfer
 ET begins with the selection of a donor
cow.
 The donor cows will contribute the embryos
to be transferred.

12. Donor Cows Have Superior
Characteristics
 High milking
ability
 High growth rate
 Outstanding
reproductive
capacity

13. Recipient Cows
 Finally, recipient cows must be selected.
 Recipient cows serve as surrogate (foster)
mothers to the calves, but contribute no
genetic information.
 For this reason, the genetic makeup of the
recipient cow is not as important as the
makeup of the donor cow.

14. Recipient Cows (continued)
 However, the recipient cow must be able to
maintain her pregnancy to term and produce
an adequate milk supply for her calf.

15. Synchronizing the Estrous Cycle
 Once the donor and recipient cows have
been selected, they must be synchronized so
they are on the same phase of their estrous
cycle.
 It is important to synchronize estrous cycles
because the reproductive environments of
the donor and recipients must be identical in
order for the embryo to survive the transfer.

16. Synchronizing the Estrous Cycle
(continued)
 The estrous cycle is controlled by the
production and secretion of hormones at the
proper time during the cycle.
 Prostaglandin (PGF2α) is the hormone used
to synchronize the estrous cycles of the
donor and recipient cows.

17. Synchronizing the Estrus Cycle
(continued)  Prostaglandin is
produced naturally
by the cow.
However, a
synthetic version
called Lutalyse is
given in one or two
injections intra
muscular in the
neck or hip to
synchronize estrous
cycles.

18. Preparing the Donor Cow to be
Flushed
 Before the donor cow is flushed, she is
superovulated with a series of injections of
Follicle Stimulating Hormone (FSH).
 Ovulation is the process of releasing eggs.
 Superovulation causes the ovary (the female
reproductive organ) to produce many
follicles.

19. Preparing the Donor Cow to be
Flushed (continued)
 Follicles are small blister-like structures
that develop on the ovary containing one
egg each.
When the follicles ovulate, the eggs are
released.
 Superovulation ensures that many eggs will
be released because there are many follicles
present.

20. Breeding the Donor Cow
When the donor shows signs of estrus (the
time period during the estrous cycle when
she will allow breeding), she is ready to
be bred.
 Some signs of estrus are riding other
cows, clear vaginal mucus, and pacing the
fence.

21. The Flush
 Once the donor cow has been bred, the embryos
are allowed to grow for six days.
 During this time the embryos also travels down
the reproductive tract from the oviduct (the site of
fertilization) to the uterus where they can be
flushed out.
 On the seventh day, the embryos are ready to be
removed. This process is called flushing.

22. The Flush (continued)
 Embryo professionals use a non-surgical
method to remove the embryos. The
process requires experience and a patient,
steady hand.

23. The Flush (continued)
 An injection of
lidocaine is given
prior to the flush to
reduce pressure and
stress on the donor
cow and to make
the flush easier for
the ET
professional.

24. The Flush (continued)
 To begin the flush, a catheter is passed
through the cervix into one uterine horn.

25. The Flush (continued)
 The catheter
contains a balloon
that is inflated with
a saline solution in
order to seal the
entrance to the
uterus so fluid and
embryos are not
lost.

26. Removing the Embryos
 The uterine horn is
filled with flush
media and massaged
to allow the embryos
to flow out of the
tract.
 This process is
repeated several
times in each uterine
horn.

27. Collecting the Embryos
 Embryos are carried
out of the reproductive
tract through plastic
tubes and collected in a
filter with the flush
media.
 The pores in the filter
are smaller than the
embryos so excess
fluid drains out of the
filter without losing the
embryos.

28. Injecting Penicillin
 After the embryos
have been flushed
out, uterus
injected with
penicillin to kill
any missed
embryos or
infections.

29. Embryo Statistics
 An average of 7-10 embryos is collected
from each flush.
 However, the number of embryos obtained
from a single flush may range anywhere
from 0-60.

30. Separating the Embryos
 In the lab, embryos
are separated from
the flush media and
examined under a
microscope to
determine their
quality and stage of
development.

31. Embryo Size and Quality
 Embryos are
microscopic in size
(about 0.2 mm).
 Only undamaged
embryos at proper
maturity should be
transferred.

32. Embryo Quality
The embryos
on the left
are damaged
and should
not be
transferred.
The embryo
on the right is
of proper
maturity and
quality and
should be
transferred.

33. Transferring the Embryos
 The embryo to be transferred is put into a
small, plastic straw and then loaded into an
embryo transfer gun.

34. Transferring the Embryos (continued)
 The embryo is then
inserted into either the
left or right uterine
horn depending on
which ovary has a
corpus lutuem (CL).
 The CL is a structure
on the ovary that
secretes the hormone
progesterone which is
needed to maintain the
pregnancy.

35. Transfer Immediately or Freeze
 Embryos should be
transferred as soon as
possible after the flush
(within 8 hours at
least).
 Embryos can also be
frozen for later
implantation and
stored in liquid
nitrogen tanks.

36. Benefits to Embryo Transfer
-A single heifer or cow is able to produce multiple
calves from the same genetic line.
-An older superior cow is able to donate ovules for
embryo transfer.
-Embryos can be frozen and stored for future use.

37. FACTS
-In 1987, 3.6% (5,105) of all calves
registered were a result of embryo transfer.
-In 2002, 25,093 calves resulting from ET
were registered. This was 8.9% of all calves
registered.
-In 2007, just under 40,000 calves resulting
from ET were registered. This accounted
for about 11.5% of total registrations.

38. Disadvantages of ET
-Increased expenses and higher breakeven costs
for calves.
• Requires a higher level of management.
• Increased potential for spread of certain
diseases.
• Not all potential donors respond positively to
treatment.

39. Summary
 ET can be costly, so the return on the
investment should always be greater than
the input costs.
 ET should only be performed using donor
cows of superior genetics.
 Bull selection should be based on superior
genetics as well.

40. Conclusion
 If the required conditions are met, embryo
transfer can be a beneficial way to produce
superior cattle.