Embryo Transfer By: Macie Wagstaff

References  "Animal Reproduction." Introduction to Animal Science. 5th ed , Print.  Bourdon, Richard M. "Chapter 20 Biotechnology & Animal Breeding." Understanding Animal Breeding. 2nd ed. Upper Saddle River, NJ: Prentice Hall, Print. Page:  Ensminger, M.E. "Genetic and Animal Breeding." Animal Science. Ninth ed. Danville Print.  Gillespie, James R. "Animal Breeding." Modern Livestock & Poultry Production. 5th ed. Albany, NY: Delmar, Print. Page:

Embryo Transfer  Is the process of collecting fertilized embryos from one female (Donor) and placing them in another (Recipient) where the embryo completes its development.

What is an Embryo ?  An Embryo is an egg that has already been fertilized by a sperm cell.

Donor  Females that produce the embryos.  Donor female must have outstanding genetics, be healthy, and reproductively sound. Recipient  Females used to carry the embryos of a donor animal throughout gestation.  Recipient female must have outstanding milk.  Acts as the Foster-Parent, but contribute no genetic information to the offspring.

 This technology become available to livestock producers in the 1970’s  Embryo Transfer gives a genetically superior female the opportunity to produce more offspring's than she could by natural reproduction. It maximizing her genetic abilities.

 Used in several species of domestic animals, especially cattle, horses, goats, and sheep.  Embryo Transfer is not used as much in Swine because they are litter producers.  It has also been used in non-domestic species, such as deer, elk, and bison.

Process Of Embryo Transfer  The process of cattle embryo transfer begins by selecting a genetically outstanding, non-pregnant embryo donor (heifer or cow). At the same time, 10 to 15 non-pregnant females (embryo recipients) need to be identified.

Super ovulation – The donor cow is super ovulated by using injectable hormones. An average donor cow produces 6 transferable embryos. However 0-25 embryos can be expected.  First, the steps for the Donor Cow

Superovulation of Donor Day 0 to Day 4  Follicle Stimulating Hormones - (Known as FSH)  Injectable hormones 2x daily, 4 days  The FSH does not increase the number of eggs being produced, it just keeps the follicle in productive and developing state, therefore resulting in more ovulating. (Day 0 starts 8-14 days following estrus cycle.)

Superovulation – Day 3  Prostaglandin injection causing Corpus Luteum regression to bring on estrus. Result: Multiple Follicles

Superovulation– Day 5  Onset of estrus ( Heat Detection )

 Insemination – When in standing estrus (heat), usually 5 days after superovulation.  Inseminated at both 12 and 24 hours after heat with two straws of high quality semen

 After 6-8 days, the embryos have developed into a transferable state. Embryo Recovery from Donor

 Insert Foley catheter with inflatable balloon into donor’s uterus.

 Insert Flushing solution (saline) is introduced into each uterine horn.  Solution filled uterine horn is gently massaged.

Recovery of Embryos  Fluid containing the embryos is drawn back out and collected though a filter into a holding cylinder.

 The solution that comes out of the tract is taken into a laboratory and searched for embryos.  Embryos located with microscope.  Embryos are washed and transferred to holding medium. (Procedure generally repeated 3 times.)  Embryos are evaluated for state of development and quality.  Initially classified: “good” or “bad.” “Good” embryos are further classified. Embryo Processing

 The embryos can be freshly transferred into another cow that is in the same part of her cycle as the donor or, they can be frozen.  Liquid Nitrogen -196°C or one day at room Temp.

The Recipient  Reproductively sound, good mothering ability.  Good overall health, nutrition.  Must be synchronized to receive the embryo.

Synchronization Protocol- Day 0  Insert intravaginal CIDR  CIDR - Controlled Internal Drug Release  Administer 2 cc combo Estradiol and Progesterone.

Day 7- Remove CIDR  Administer 5cc Prostaglandin. Day 8- Final Injection:1cc Estradiol  Observe for onset of estrus.  Day 16- Transfer Embryo

Cost

Advantages  Improving productivity of dams and sires more quickly because of the increased number of offspring's in a shorter period of time.  Extending the productive life of a female that has been injured and can no longer carry an offspring to term

 Faster Genetic Improvement in the Herd.  Prevents disease transmission.  Reproduce some endangered species faster than normally possible

Disadvantages  Increased expenses and higher break-even costs for calves.  Estrus detection required.  Synchronization of recipient with donor.  Specialized equipment and trained personnel.  More expensive and time consuming than traditional reproductive methods.

Review Questions 1.What is the process of collecting fertilized embryos from one female (Donor) and placing them in another (Recipient) where the embryo completes its development? 2.What acts as the Foster- Parent? 3.An average donor cow produces ____ transferable embryos. However 0-25 embryos can be expected.