By: Valerie D. Blair and Dr. Frank B. Flanders - PowerPoint PPT Presentation

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Embryo Transfer in Cattle By: Valerie D. Blair and Dr. Frank B. Flanders Georgia Agricultural Education Curriculum Office Georgia Department of Education – PowerPoint PPT presentation

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Title: By: Valerie D. Blair and Dr. Frank B. Flanders


1

Embryo Transfer in Cattle
  • By Valerie D. Blair and
    Dr. Frank B. Flanders
  • Georgia Agricultural
    Education Curriculum Office
  • Georgia
    Department of Education
  • Edited by Josh Christiansen Flandreau
    Public Schools

2
Introduction
  • This slide show is a general overview of embryo
    transfer (ET) in beef and dairy cattle.
  • It includes a brief discussion of the benefits
    and instructional methods of ET.

3
Introduction (continued)
  • ET is a expensive procedure, costing around 300
    for each flush and approximately 270 for each
    calf born.
  • Students should understand that ET is a
    complicated procedure with a fairly high
    difficulty level.
  • ET should only be performed by trained
    professionals.

4
Objectives
  • Explain the benefits of embryo transfer.
  • Briefly outline the procedure of embryo transfer.

5
Reproductive Anatomy
6
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.

7
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.

8
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.

9
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.

10
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.

11
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.

12
Necessary Equipment for
Embryo Transfer
  • Plastic media bag
  • Foley catheter
  • Embryo filter

13
Necessary Equipment for Embryo
Transfer (continued)
  • Microscope
  • Straw
  • Rod

14
Necessary Equipment for Embryo
Transfer (continued)
  • FSH
  • Prostaglandin
  • (Lutalyse)

15
Necessary Equipment for Embryo
Transfer (continued)
  • Penicillin
  • Lidocaine

16
Necessary Equipment for Embryo
Transfer (continued)
  • Plastic Sleeve
  • Bull Semen

17
The Process of Embryo Transfer
  • ET begins with the selection of a donor cow.
  • The donor cows will contribute the embryos to be
    transferred.

18
Donor Cows Have Superior
Characteristics
  • High milking ability
  • High growth rate
  • Outstanding reproductive capacity

19
Bull Selection
  • Next, a bull with superior genetics should be
    selected.
  • Breeding can occur naturally or by artificial
    insemination.

20
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.

21
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.

22
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.

23
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 (PGF2a) is the hormone used to
    synchronize the estrous cycles of the donor and
    recipient cows.

24
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 to synchronize
    estrous cycles.

25
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.

26
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.

27
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.

28
Breeding the Donor Cow (continued)
  • If using artificial insemination, the donor cow
    should be bred at least twice to ensure that all
    eggs are fertilized.

29
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.

30
The Flush (continued)
  • Embryo professionals use a non-surgical method to
    remove the embryos. The process requires
    experience and a patient, steady hand.

31
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.

32
The Flush (continued)
  • To begin the flush, a catheter is passed through
    the cervix into one uterine horn.

33
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.

34
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.

35
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.

36
Injecting Penicillin
  • After the embryos have been flushed out, uterus
    injected with penicillin to kill any missed
    embryos or infections.

37
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.

38
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.

39
Embryo Size and Quality
  • Embryos are microscopic in size (about 0.2 mm).
  • Only undamaged embryos at proper maturity should
    be transferred.

40
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.
41
Transferring the Embryos
  • The embryo to be transferred is put into a small,
    plastic straw and then loaded into an embryo
    transfer gun.

42
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.

43
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.

44
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.

45
Conclusion
  • If the required conditions are met, embryo
    transfer can be a beneficial way to produce
    superior cattle.
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