1) Embryo transfer involves super-stimulating a donor animal to produce multiple embryos and then surgically flushing them from the donor's uterus. The embryos are then transferred into the uterus of a recipient animal. 2) The history of embryo transfer began in the 1890s with early successful transfers between different animal species in later decades. Today it is commonly used in cattle breeding programs. 3) Embryo transfer has advantages over importing live animals or semen as it has a very low risk of disease transmission, low costs, and allows for the passive immunity from the native recipient dam.

1. EMBRYO TRANSFER
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8-cell embryo for transfer 3 days after fertilization

2. EMBRYO
TRANSFER
Objectives
Definitions
History
Animal
components of
ET Program
Advantages
and
Disadvantages
of an ET
Program
2
Contents

3. Management
of
components
of ET
Program
Super-
ovulation
Flushing Freezing
Transferring
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4. Objectives
1. To introduce the process of super-ovulation and embryo
transfer (ET) in cattle and horses.
2. To provide an overview of the advantages and
disadvantages of ET in cattle and horses.
3. To review the process of ET including flushing,
searching, handling, grading, freezing, thawing, and
transferring embryos.
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5. What is Embryo Transfer
 Multiple injections of hormone to stimulate and multiply
the ovulations in the cow that you want to get the
embryos from (Cruachan.com)
 Step in the process of assisted reproduction in
which embryos are placed into the uterus of a female
with the intent to establish a pregnancy (Wikipedia.com)
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6. History of Embryo Transfer
1890s: First successful embryo transfer
1971: First successful embryo transfer between donkeys
and horses
1974: Birth of horse foal following non-surgical embryo
transfer to recipient mare
1984: Foals born in Japan produced using frozen embryos
1984: First successful embryo transfer between two equine
species (zebra-horse)
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7. History of Embryo Transfer
1990s: Embryo transfer procedure starts to take off in
Argentinean polo ponies
2002: University of Sydney claims first sex sorted
pregnancy by embryo transfer
(Reproduction-online.org)
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8. Comparison Of Importing Germplasm As
Postparturient Animals, As Semen Or As
Embryos
Advantages Disadvantages
Post parturient animals
Animals productive
quickly
Expensive
Animals often succumb to disease
Chance of introducing exotic
disease
Complex transportation logistics
Limited immediate genetic
influence if females are imported
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9. Semen
Inexpensive
Need to grade up to get pure-
bred animals*
Low risk of disease
transmission
Need for Al technology
Hybrid vigor, F1 and F2* Long wait until animals productive
Simple transportation
logistics
Passive immunity from
native dam
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Comparison Of Importing Germplasm As
Postparturient Animals, As Semen Or As
Embryos

10. Embryos
Very low risk of disease
transmission
Need for ET technology
Costs may be lower than
animals
Long wait until animals
productive
Simple transportation
logistics
Passive immunity from
native dam
10
Comparison Of Importing Germplasm As
Postparturient Animals, As Semen Or As
Embryos

11. Animal Components of ET
Program
Donor: animal that donates embryos
Selection criteria are used to select a donor.
Embryo from a donor cow does not guarantee a superior
calf.
Reproductive soundness
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12. Animal Components of ET
Program
Recipient – animal that receives embryo from the donor
Surrogate
Criteria for selection
Pregnancy rates
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13. ET Process
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14. Super-ovulation
 Process of super stimulating the ovaries with FSH to
produce multiple oocytes.
 Includes frequent treatment of females with FSH for a
period of four days.
 Females are administered prostaglandin during the third
day of FSH injections to regress any CL present.
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15. Flushing
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16. 16

17. Flushing
 12-24 hours at a pH of 7.1 to 7.5 when holding media
is changed every few hours. Excessive temperature harms
embryos (39oC).
 Embryos are classified by stage of development and
graded based on gross morphological appearance.
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18. In-vitro Fertilization (IVF)
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19. Vitrification & Recovery
19

20. Vitrification & Recovery
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(International Livestock Research Institute, 2015)

21. Freezing
1) Cryoprotectants are used to dehydrate cells and protect
the cells of the embryo during the freezing and thawing
process.
 Direct transfer (DT) embryos- embryos frozen in ethylene glycol
2) Embryos are equilibrated for 5 to 10 minutes in
cryoprotectant freezing medium.
3) Embryos are frozen in a step-wise procedure in a special
freezing machine.
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22. Types of ET
Surgical
 Vs. non-surgical transfer, it is more time consuming,
expensive, labor intensive, and riskier to the recipient
mare but more successful than non-surgical methods.
 A surgical incision is made into either:
Midventral Laparotomy
Flank Incision Procedure
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23. Types of ET
Nonsurgical
 Position embryo in sterile pipette in medium between two
air spaces.
 Manually guide pipette through cervix into uterus.
 Deposit embryo in uterine body
(Betteridge, 2015)
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24. The Difference Between Surgical
And Non - Surgical Transfers
 Surgical transfer places the embryo further up the
uterine horn than non-surgical.
 Surgical transfer requires a small cut in the cows flank on
the side of the ovulation.
 The uterus is pulled out and a small hole is made to the
uterus. A small catheter is placed in through the hole and
the embryo released.
 Non surgical is the same as A.I. The embryo is placed in
the side of the ovulation and released from the gun.
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25. Transferring
Embryos can be transferred in two different manners
A. Same day transfer
B. Transfer of Frozen Embryos
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26. Process of Transferring Embryo
1. The recipient is palpated to determine the presence and
location of the CL (right vs. left).
2. If the embryo is frozen it is thawed in a warm water
bath (92°F) for <30 sec and placed in a specially
designed transfer gun and covered with a sterile sheath.
3. The embryo is deposited 1/3 the way up the uterine
horn.
4. Pregnancy rates
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27. Embryonic Development
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Oocyte Zygote 4 cell
8 cell BlastocystMorula

28. Conception Rate
 Rate should be 5-10% higher than artificial insemination,
but a lot depends on the condition of the recipients.
 A.I. program the conception rate is 60-65%
 Embryo transfer program it is expected roughly the same
sometimes a bit higher (Cruachan.com)
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Pregnancy Diagnosis
 The fetus can be sex scanned between days 56 to 65 of
pregnancy as by then subsequent losses should be minimal
and it can be useful to know whether a bull or a heifer ET
calf is expected (Xlvets.co.uk)

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30. END
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