For the Instructor

● Students will:o Have a basic understanding of what Embryo

Transfer is and understand its componentso Be able to summarize the processes and

understand how Embryo Transfer workso Know the pros and cons of using Embryo

Transfer in cattle● Animal Science

o Standard: D4.4

E.T., Moo Home

Breanne Pacheco

Embryo Transfer in Cattle

Embryo Transfer

What is it?

What is the process?

What are the pros/cons?

What is it?

● embryos (fertilized eggs) are collected from the uterus of donor cows

● transferred to the uterus of a recipient cow or heifer for the duration of gestation

● Most common in beef and dairy cattle

Process

1. Selection of donor cow2. Superovulation of donor cow3. Insemination of the cow4. Flushing the embryos5. Evaluation of the embryos6. Selection and preparation of

recipient females7. Transfer of the embryos

Selection of Donor Cow

● selection is based on producer preference● reproductively sound● regular heat cycles● no more than two breedings per conception● no parturition (calving) difficulties● no detectable genetic defects● appropriate nutrition

Think Break!

Turn to a partner:● What qualities do we

want for a good donor cow?

● Which of these two cows would you select as your donor?

Superovulation of Donor Cow

● release of multiple eggs at a single estrus (standing heat)● ~85% of donors will respond with an average of 5 transferable

embryos● stimulates development of follicles (contain the eggs) with FSH

(follicle-stimulating hormone) when a CL (corpus luteum) is on the ovary

● prostaglandin (hormone) injection given - causes the donor to come into estrus within 48-60 hrs

● FSH - makes follicles form on the ovary

● Follicles will eventually rupture and release an egg

● CL - yellow blister-like structure that forms after the eggs are released

● CL secretes a hormone that helps maintain pregnancy

Insemination of the Cow

● inseminate multiple times during and after estrus

● high quality semen with high percentage of normal, motile cells

● semen placement should occur in the body of the uterus

https://www.infovets.com/healthycowinfo/Images/A716-08.jpg

Flushing the Embryos

● small rubber catheter is inserted through cervix of donor cow

● special medium is flushed through the uterus to harvest embryos 7-8 days after estrus

● embryos are collected in a collection flask

Tools and Equipment:● Foley catheter: 2-way cather

that has one channel for inflation of a balloon at the end plus an additional channel for the inflow and outflow of flushing medium

● collection flask● flushing fluid● donor and recipient

How Does it Work?

Think Break!

Turn to a partner:● What is the importance of FSH?● What is the importance of a CL?● Summarize the flushing process

Evaluation of the Embryos

● located individually under a microscope● evaluated for quality and classified by their potential

likelihood of success if transferred● Classified under subjective criteria:

o Grade 1: Excellent or Goodo Grade 2: Fairo Grade 3: Pooro Grade 4: Dead or degenerating

Embryos are also evaluated on stage of development:

Selection and Preparation of Recipient Females

● young dairy cows in good body condition

● reproductively sound, exhibit calving ease, have good milking and mothering ability

● proper nutrition and body scoreo Body condition score of 6 for

Beef Cowso Body condition score of 3 or 4 for

Dairy Cows● synchronized with donor cow

Transfer of the Embryos

● embryo is “loaded” into a ¼-ml insemination straw under a microscope

● recipient cow is palpated to determine which ovary has ovulated

● transfer gun is passed through the cervix until the tip of the gun slides into the horn with the active CL

● embryo is gently expelled into correct horn

Pros

● increases number of offspring sired by “superior” females

● faster genetic progress● increase frequency of desired matings● obtain offspring from old or injured

animals● increase farm income through embryo

sales● exporting/importing embryos is easier

than live animals

Cons

● can be expensive● success rates are less than AI● cost and maintenance of recipient females● technician with the skill to flush embryos

from the reproductive tract● possible spread of disease through

recipients

Opportunities:

● FFA:o Vet Science Team

● Career:o Embryo Transfer

TechnicianThis could be you!!