It’s fair to say embryo transfer (ET) isn’t a common practice for most U.S. beef herds. Current data indicate that less than 5% of cow-calf operations have adopted ET technology.
However, embryo usage is growing. According to the International Embryo Transfer Society, the number of embryos produced significantly increased from 2013 to 2022, up 564%. And an increasing share of those embryos is being placed in beef recipients.
The reasons are simple:
- Embryos offer a way to quickly accelerate a herd’s genetic base using existing females, especially those with superior production or maternal traits. Those of poor or average genetic potential serve as surrogates to carry a calf of exceptional genetic merit.
- Embryos enable beef producers to switch breeds in a single generation or increase pregnancies during periods of reduced fertility, such as heat stress.
- ET programs are also recommended to optimize the benefits of expensive semen. One semen straw can fertilize between 100 and 300 oocytes (eggs). This means that one straw is enough to fertilize the eggs harvested from several donors.
Getting started with ET
Embryos can be produced in two ways:
- In vivo (inside the cow) embryo production from donor females, also known as superovulation programs
- In vitro (in a lab) procedures, followed by in vitro fertilization (IVF)
IVF technology and processes have rapidly evolved over the years, making this reproductive tool an economically beneficial practice for operations of all types and sizes.
Advancements in cryopreservation (freezing) have also decreased the number of recipients required and relaxed the timing requirements of ET, making it more feasible and efficient for many producers.
Before implementing a program, investigate proper procedures and consider how you will adopt these steps with your herd and facilities. Then, commit to following them. For instance, it may not be the best idea to start an ET program if you don’t already have a successful artificial insemination (A.I.) program in your operation or if you don’t have experience with estrus synchronization. Master those technologies first, then expand into ET.
5 keys to ET success
The most successful operations follow strict protocols grounded in the science of ET. To set your program up for success, consider the following recommendations. ET training is highly recommended before diving into a program. Be sure to understand the needed processes and physical requirements as you build protocols.
1. Choose optimal ET recipients
Select first-, second- and third-lactation cows in adequate body condition, targeting those undergoing first, second or third service. Follow a mandatory waiting period after calving. Keep in mind, heifers are slightly better recipients than cows due to higher fertility.
Avoid cows with a history of reproductive problems – for example, anestrus cows result in much lower conception rates following synchronization.
2. Maximize estrus synchrony between the recipient and the age of the embryo
Recipients should be seven days postestrus at the time of transfer. Make sure to coordinate these schedules before placing embryos.
3. Properly thaw and handle embryos
First, prepare clean, warm equipment. Bring the thaw bath and gun warmer to the correct temperature. Thaw one straw at a time by airing for a few seconds, placing it in warm water for 30 to 60 seconds, then drying. Load the straw correctly (don’t cut the cotton plug). Keep the gun and sheath sterile and warm. Record IDs and aim to transfer within about 15 minutes to avoid temperature swings.
Tip: Use a thaw bath that is set to the correct temperature recommended by the IVF production facility.
4. Use proper transfer technique
It’s important to place embryos properly and with good technique. Work gently to avoid endometrial trauma. Steady hands and smooth motions win the day. Collaborate with a skilled technician to help ensure success, especially for steps three and four.
5. Take your time
Don’t rush through the steps leading up to embryo transfer or change the transfer technique. Steady, deliberate and consistent practices are the cornerstones of success.
With ET, you can expect to achieve pregnancy rates similar to those achieved with A.I. Heat-stressed animals and repeat breeders can even show an improvement in pregnancy rate over A.I. because the implanted embryo circumvents fertility-related challenges and starts with the placement of an already viable embryo.
Keep in mind that pregnancy rates vary due to factors such as environment, animal management, recipient quality and season.
Ultimately, embryos have been a reproductive tool for decades and are not just for herds with elite genetics. Given current market opportunities and the smaller national beef cattle herd, now is a good time to reconsider this option.
Avoid these common ET miscues
Adopting embryo technology is a significant change from natural service and A.I. programs, and it cannot be managed in the same way. Increase your odds of success by avoiding protocol and adherence pitfalls that can derail ET programs.
Common mistakes include:
- Failure to follow injection schedules and doses
- Not managing the recipient's body condition and health
- Improper semen or embryo handling
