For the Instructor ●Students will: o Have a basic understanding of what Embryo Transfer is and understand its components o Be able to summarize the processes and understand how Embryo Transfer works o 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 cow 2.Superovulation of donor cow 3.Insemination of the cow 4.Flushing the embryos 5.Evaluation of the embryos 6.Selection and preparation of recipient females 7.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 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

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 Good o Grade 2: Fair o Grade 3: Poor o 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 score o Body condition score of 6 for Beef Cows o 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 Technician This could be you!!