When you think of bovine embryo transfer, it’s likely you view it as a technique geared toward the seedstock industry.
This advanced reproductive technology is a well-established tool for purebred breeders, and now some embryo transfer practitioners are seeing opportunities for its growth in commercial breeding programs.
“Embryo transfer or IVF is not a technology that (commercial producers have) really looked at because it’s been focused on purebred herds,” says Dr. Rob Stables, general manager and head veterinarian at Bow Valley Genetics, an advanced bovine reproduction facility at Brooks, Alta.
At Bow Valley Genetics, which offers both conventional embryo transfer (ET) and in vitro fertilization (IVF) as well as semen collection, Stables has seen some producers with large commercial herds use ET to create their own bull batteries. Another opportunity, however, is available for producers who want to place greater emphasis on the role of females in improving commercial cattle.
In November, Bow Valley launched the Advanced Reproduction Centre (ARC) in partnership with WestGen, an artificial insemination (AI) co-operative that is part-owner of Semex. This program will initially focus on dairy herds, due to the advancement of dairy genomic models, as data is collected on dairy females at every milking.
First, a herd will be genomically tested and ranked. A producer can choose the traits they want to select for and use the genomic results to place the females into groups.
“It stratifies the herd so that you’re picking your replacements out of the very best,” says Stables. “On the very top end, if you’ve got cows that are high enough, then you’ll pick those few cows to use as donor cows for embryo transfer or IVF.”
“We’ve got some data on herds that have done this, and in two, three years they can make a huge leap from below industry average up into the top 10 per cent, for example. They know this because they don’t have to wait for those daughters to get into milk,” he says. “As soon as they’re born they can genomically test them.”
On identifying the top animals, the team at Bow Valley will perform the collections and transfers for high-end donors. There are techniques to make this more cost efficient, such as putting the IVF embryos from three donor cows in one dish in the lab, instead of separate dishes that are charged individually. They’ll also examine the top cows to ensure they’ll be good potential donor cows with the ability to produce high follicle numbers.
Applying this program to beef herds will be similar, creating the potential for commercial breeders to make genetic improvement through both the bull and female sides of the equation, rather than focusing solely on the bull side through choice of sires. This project is designed to fit any genetic selection tools, including performance trait data programs.
However, using phenotypic data alone can lead to more variation in results, based on environmental influences on an animal’s performance.
“For instance, you might have a heifer or a bull that doesn’t perform very well on the trait that you’re looking for, but they had severe scours as a calf and it damaged their intestines,” Stables says. “It just wasn’t able to express its genetics to its full potential because of the environmental effects.” Although this can influence the data used in the ranking system, one could still make significant genetic progress.
The beef side of this program is in its trial phase, with interested commercial producers now in discussion with Bow Valley and WestGen.
“We’re willing to talk to anyone that’s interested in that, where they may already have some sort of program that they’re working on,” he says. “Then it’s a matter of what can we do to accelerate that top end so that it’s multiplying those top cows that they’ve already identified.”
Rise of IVF embryos leads to new opportunities
The use of IVF for beef cattle is growing each year, something Stables is seeing at his own facility. “June was the first time that we had more cows on IVF at our facility than we did on conventional ET,” he says.
In addition to being a proven technique with sound conception rates when performed correctly, conventional ET is less expensive than IVF. However, that is changing, as IVF costs are decreasing with different lab methods. With conventional ET, a donor female needs to be kept open to be bred and flushed, and cows can be collected at a minimum of every 30 days.
“It limits the number of collections you can do in a year, and generally most cows start to decrease after a few cycles,” says Stables.
Collections every two weeks are possible with IVF, as the eggs are collected directly off the ovaries, not from the uterus. This also allows a person to collect from pregnant cows. After confirming by ultrasound that they’re 30 to 35 days in calf, the female receives the Folltropin super-stimulation drug to produce multiple follicles. The vet then uses an ultrasound-guided needle to aspirate the follicles off the ovaries. In the lab, follicles are matured and fertilized before being cultured for seven days.
“Between more rapid turnover and doing them when they’re pregnant, you can get more embryos in a year produced,” he says. “Typically, people might do a flush after she calves, get her bred and then they’ll continue on doing IVF while she’s pregnant.”
When IVF was introduced, there were issues with lower conception rates, birth weight and some calf deformities reported, but these have been eliminated as the technology has advanced.
“The results are getting more reliable all the time, and they’re directly comparable to conventional ET at this point,” he says. “We find no difference in our pregnancy rates with IVF embryos versus conventional embryos.”
Despite this, Stables doesn’t anticipate conventional ET falling out of favour. “There’s a place for both, and it depends on what your goal is,” he says.
For example, if a breeder plans to export embryos, conventional ET is the easiest choice, as minimal health testing is required. This isn’t the case for IVF embryos.
“We can’t guarantee that they’re free of disease quite the same way as conventional embryos,” he says. “The surface of the shell around the embryo is stickier, so getting viruses and bacteria removed from that, washed off, is tougher.” Currently, there are fewer export certificates for IVF embryos, but more are becoming available.
Looking ahead, Stables predicts the use of genomics for genetic selection will become more popular in the next decade.
“The technology is going to just continue to advance, the accuracy is going to get better and there will be more and more traits available for it as the technology progresses,” he says. “It won’t be for everyone, but certainly some people will learn how to make use of it and incorporate it into their program.”
He also anticipates greater use of sexed semen in the beef industry, which is currently less popular because of the need for both heifer and bull calves.
“Currently, there is a limited amount of sexed beef semen available on the market, but that will change if the market demands it. The cost to produce sexed semen is quite high and is a time-consuming process, which both limit the volume that is produced,” he says.
Another restriction, he adds, is that many producers haven’t considered using AI because of the skill, labour and time required to heat detect or synchronize females.
“Recent developments have led to the rise of Fixed Time artificial insemination protocols that allow everything to occur on a schedule, with no heat detection, and a predetermined time to breed. This makes it much easier to schedule help and AI technicians.”
Attracting more vets and technicians
While studying animal science at the University of Manitoba, Patricia Fawley wasn’t aware of the opportunities to work in the field of bovine ET without being a veterinarian. The ET process wasn’t covered in detail in her classes.
“I always thought it was something they could dive a bit more… into, but when I asked my professor about it, they said they don’t have the knowledge,” she says.
Fawley, who was raised in Winnipeg, reached out to reproductive technology companies to learn more about job opportunities, but was told only veterinarians worked in these roles. It wasn’t until she heard about an opening at Bow Valley for an embryo technician that she learned this role was an option.
“It combines the traditional farming aspect with the scientific aspect,” says Fawley, who worked as a technician at Bow Valley after finishing her degree. “I thought that the embryo transfer was pretty much the perfect job for me in combining my love of farming and my love of science.”
Fawley, who is currently in her first year at Ross University School of Veterinary Medicine in St. Kitts and Nevis, would like the technician opportunities to be better promoted to young people who may be interested in this field but don’t plan on becoming a veterinarian.
“I don’t think a lot of people know about how much we are able to do as embryo technicians because I had no idea,” she says.
While all lab work has to be signed off by a veterinarian certified by the Canadian Embryo Transfer Association, technicians play an important role in the collection and processing of embryos. When Fawley worked at Bow Valley, her days would vary from assisting veterinarians chute-side with embryo or semen collection to working in the lab to search for and process embryos or analyze semen.
While there is a decently sized community of Canadian veterinarians who specialize in ET, with approximately 120 practitioners certified by the Canadian Embryo Transfer Association, bringing in new veterinarians can be a challenge.
“Our purebred market has traditionally been geared a lot towards export, so proportionately there’s a lot more export-certified practitioners under the total number of ET vets in Canada,” says Stables.
“The one problem that we have, typical in the vet profession and rural practice, is a lot of the vets are getting older and starting to run into a rash of people retiring. There’s some new people coming in, but they tend to be people that are established in practice and want to do it as a side rather than as a full-time job.”
Basics of embryo transfer
Embryo transfer (ET) is used to increase the progeny from a top-quality female, allowing her genetics to make a greater impact on herds. In conventional ET, or in vivo, donor females are given a treatment using a follicle-stimulating hormone, which causes the ovulation of several follicles. After being bred by artificial insemination, embryos are flushed from the cow’s uterus seven days later, and viable embryos are implanted into open recipient females, who have been heat-synchronized for the implant date. On average, each collection will result in about six to seven viable embryos, though that can vary. Embryos can also be frozen and stored in liquid nitrogen until a later date, when they can be thawed and implanted. In Canada, all veterinarians must be certified by the Canadian Embryo Transfer Association to transfer embryos for export.