Embryo Transfer Services
Embryo transfer is a genetics progress tool - a way to achieve genetic goals faster. The process comprises a series of operations, each of which needs to be carried out successfully in order to maximize the results of your program. Failure of just one part of the procedure can lead to failure of the overall program.
These guidelines have been developed based on the experience of our veterinarian team interacting with clients to help avoid oversights and achieve success in applying embryo transfer.
Donor and Recipient Preparation:
- All donors and recipients in the program should be palpated by your local veterinarian to ensure their suitability prior to the first injection of hormones.
- Donors should be selected based on superior genetic merit (based on your goals), ideally should have produced a calf each year and be reproductively healthy.
- Donors should be at least 8 weeks calved before the programming begins.
- Donors as young as 12 months can be used, however, open heifers and cows over 12 years of age are less predictable in their response to superovulation and collection.
- Recipients should be reproductively sound, with no history of infertility or calving problems. Open heifers ready to breed (16+ months & 350+ kg), and younger animals having one or two calves are ideal recipients.
- Cows with more than 5 or 6 calves should be avoided for use as recipients, especially if they have shown any fertility problems such as retained placenta or infected uterus.
- We advise that all recipients be tested for LEUKOSIS and NEOSPORA prior to synchronizing them to receive an embryo. These tests will help you select recipients with the greatest chance of producing a live healthy calf from your ET program.
Nutrition and Embryo Transfer:
- As a rule of thumb, the donor and recipient cattle should be on a rising plane of nutrition to achieve maximum embryo fertility and pregnancy rates.
- Animals that are being flushed repeatedly should be put on a rising plane of nutrition for each program, and keeping them on a maintenance ration between programs. In practice, this means providing the best possible feed to the donors from one (+) week before the program begins until the collection day.
The Superovulation and Synchronization Program:
- During the superovulation and heat detection periods, it is very important to allow for enough time to carry out all aspects of the program at the times indicated in the program and heat detection forms.
- All injections should be given intramuscularly in the hip or the muscle of the hind leg using a 1 1/2 inch needle. Shorter needles do not place the drug adequately into the muscle.
- Use one syringe for prostaglandin (e.g., Estrumate) and another for the superovulation hormones. Do not mix syringes.
- For cows working off a natural heat, the time from the first hormone injection to embryo collection is 12 days. Please inform us of the date the donor was in heat at the time of your phone call to schedule a visit to examine your donor.
- If we need to initiate a startup heat, the time from the first injection to collection is on average 24 days. The first step is to pre-synchronise the donors and recipients with an injection of prostaglandin (Estrumate or Lutalyse to name two).
- About 13 days after the first injection, or from 7 to 13 days after heat, the donors are superovulated with a 4 day injection program of the hormone FSH, given morning and evening. In the middle of this schedule, the donors and recipients are given an injection of prostaglandin to bring them into heat.
- The donors are bred two or three times, once ten to twelve hours after the start of standing heat, and again 12 hours later. If a donor is still in standing heat at the second AI, a third breeding should be applied 12 hours after the second AI.
Heat Detection:
HEAT DETECTION is one of the most important aspects of an embryo transfer program. The time that you invest in heat detection with both your donors and recipients will pay dividends in terms of more transferable embryos and better pregnancy rates in your recipients. In general, to best serve your program, any recipient that has not shown standing heat will not receive an embryo.
- Check all animals for heat beginning one full day before the donors are due in heat to two days after.
- All heat checking should be done at first light, midday, at dusk, and at 11 PM to midnight. Please record the time of day and date that the recipients show standing heat.
The Day of Collection and Transfer:
Seven days after breeding, the staff of CPGC/AVC will come to your farm to carry out the embryo collections, embryo sexing and embryo transfers and if necessary embryo freezing. The day and date of the flush is shown on the donor program.
- We will need the following in order to carry out work on your farm:
- A small table or barrel next to the chute or stanchion.
- A clean room with space for a table for our portable sexing laboratory.
- If you are not sexing, some desk space is all that we will need.
Results Achievable Using Embryo Transfer:
The results vary from farm to farm and program to program, however donors tend to respond similarly flush to flush. If your donor does not respond to hormones, or fails to produce viable embryos on her first try, we can modify her program on a subsequent superovulation and quite often achieve good results.
The following figures are averages only, and do not constitute a guarantee of results.
- On average, 6 viable embryos are collected from each flush (range 0-40).
- We generally achieve a 60++% pregnancy rate. It is not unusual to achieve an excellent pregnancy rate with sexed embryos if the recipients are properly selected and prepared.
- Should you have more embryos than recipients we will freeze the best embryos and transfer the rest to fill the suitable recipients.
- Embryos can be frozen and stored indefinitely. Freezing is an insult that can reduce the embryo survival rate, but because the best embryos are frozen, the pregnancy rates are essentially identical to fresh embryos.