Improving genetics: Embryo transfers allow more selective cattle breeding


BUFFALO — Michael Rea focused the lens of his microscope, scanning each section of a small dish, sifting through specks and smudges, looking for something. Behind him, Brent and Stephanie Painter monitored his progress on a small, black tablet. The garage was quiet, other than the sound of the wind. 

Rea shifted in his seat. 

“It’s not looking good,” he said to the Painters. 

They were looking for embryos, and it wasn’t going well. 

The Painters had hired Rea to extract as many embryos as he could from a promising young heifer. If all went according to plan, they would transfer the embryos to commercial cattle able to bring the embryos to term, increasing the number of genetically superior cattle the Painters could raise in a year — and their profits. An expensive and time-consuming process, it would be well worth the cost if it worked.

It wasn’t working. 

Trixie, the heifer, had produced just a handful of immature egg cells, none of which were usable. Rea wasn’t shocked. He said that heifers who hadn’t borne a calf before, like Trixie, weren’t great candidates for embryo transfer. Still, he collects an average of seven decent embryos from each cow he works with, he said. To find none was unusual. And frustrating.

If Rea couldn’t find an embryo, that was time and money down the drain for the Painters, who operate Painted Cattle in Johnson County, a show-cattle-producing company. They had another option, though, a second cow that might be able to make up for Trixie’s shortcomings.

“Hopefully, this cow will bring us up to average,” Rea said, putting away the equipment he’d used on Trixie. “Or she could take us over average hopefully.”

Embryo transfer isn’t new. The first successful transfer occurred in 1890, when scientists transferred embryos between rabbits, according to a history of bovine embryo transfer published by the Western College of Veterinary Medicine. Since then, the practice has expanded to all sorts of animals: rats, mice, sheep, pigs, goats, horses. The goal, always, is to improve the genetic stock of the herd.

The first successful bovine embryo transfer occurred in the 1950s, but it required extensive surgery. In the 1980s, scientists developed a way to extract and transfer the embryos without surgery, a much safer method. But it’s still not cheap. It takes a month of work to prepare and, even on the small scale the Painters attempted, well over $1,000, they said. As of 2017, just 3 percent of American cattle operations conducted embryo transfer, according to the U.S. Department of Agriculture. 

The payoff can be significant, though. Over a short period of time, the genetic quality of a herd can be drastically improved. So can the profits.

“I mean, the sky’s the limit, really,” Brent Painter said. “Start them at $1,500 and they could sell for $10,000.”

Last year, Brent traveled to Mississippi to learn how to conduct embryo transfer as part of his mission to produce the best possible show calf. That mission, begun when he started Painted Cattle in 2018, is also a passion. He could spend his whole day in the barn, watching the cattle and scrolling through the latest research on his phone, he said. Sometimes he does.

“I want to be the show calf producer for Johnson County,” Painter said. “I want to compete with the guys in Iowa that have been doing it for 30 years now.”

Embryo transfer could help him achieve that goal.

Due to the equipment required, Painter hired Rea to “flush” the two cattle he’d selected as embryo transfer candidates, extracting their embryos.

Before flushing, the cows undergo a month of hormone treatment — sometimes as many as two shots a day — to stimulate “superovulation” and produce multiple eggs at one time. Both the embryo-producing cattle and the embryo-receiving cattle must also be synchronized, so that they are in the same stage of their estrous cycle. 

Once they’re ready, the cows are artificially inseminated and, seven days later, ready to be flushed. The embryos collected during flushing can either be transferred immediately to recipient cows or be frozen.

The Painters’ intention was to transfer the freshly flushed embryos to six recipient cows they had prepared. But that plan hinged on finding embryos in the first place.

Rea pulled on rubber work boots and a navy blue jumpsuit with the sleeves torn off. The Painters’ second cow and second chance was Roxy, a big black cow who’d already borne a calf. Rea began by administering an anesthetic to the base of Roxy’s tail and applying a disinfectant to her hindquarters. With a red plastic glove pulled up to his shoulder blade, Rea inserted a catheter through Roxy’s cervix and into her uterus. 

To the catheter, Rea attached two plastic tubes. One led to an IV bag with a mixture of saline, antibacterials and surfactants (surfactants reduce surface tension). The other emptied into a plastic pail. 

Now began the slow process of flooding and flushing the uterus. With his left arm inserted into Roxy’s rectum, Rea massaged the uterus, waiting until it was filled with the IV solution. Then, with his right hand, he switched the direction of the solution and let it flow back out, down the second tube, where it trickled into the plastic pail and passed through a filter that caught any potential embryos. A cow’s embryo is about 130 microns large — twice the size of a human hair. 

The process of filling the uterus and flushing it, over and over again, takes 20 to 30 minutes. Rea kept his head down, feet crossed. As he worked, the Painters watched. For the most part, the barn was silent. Rea spoke only occasionally, murmuring to Roxy, who lashed out with her back legs whenever she sensed he was close.

Based in Billings, Montana, Rea travels across Montana, Wyoming, Colorado and even into Nebraska and North and South Dakota to conduct flushings and transfers. It keeps him busy for most of the year, doing as many as 20 flushings a week, he said. His new pickup — purchased just three days before — already had 2,500 miles on it when he arrived at the Painter barn. 

Bovine embryo transfer runs in Rea’s family. Rea learned how to transfer embryos from his father and spent several years in Russia. There, he helped transfer as many as 2,000 embryos in just five weeks, he said. 

What embryo transfer requires, Rea said, isn’t so much training as it is experience. That can be hard to come by initially, since owners want the best care for their cattle. 

“It’s an investment for them, and their genetics are important. They don’t want you practicing. They want you to be good,” Rea said. “So, luckily, I got practice there (in Russia). I’m confident. I mean, I haven’t gone broke.”

Rea’s experience was telling him something was wrong. As he waited to finish flushing Roxy, he’d detected an anomaly in her uterus’ right horn. A year ago, Roxy had undergone a cesarean section during a difficult birth. The C-section had gone well, but apparently during the healing process, the right side of her uterus had fused to the wall of her stomach, a condition that Rea could feel. 

“That doesn’t feel good,” Rea told the Painters as he stripped off his glove.

Roxy’s left horn was fine, and it was possible that, during pregnancy, the right horn could tear away from the stomach wall, Rea said. But it drastically decreased the chance that she would produce usable embryos. 

But there was still a chance.

Rea took the filter back to his workstation in the garage. There, he began the search once more, side to side, grid by grid. As he searched, the wind roared. 

“Jesus,” Brent muttered, eyes on the tablet screen and hands in his pocket. Stephanie stood next to him, her arms crossed. They were silent. 

After a few minutes, Rea extracted a little fluid from the dish and deposited it into a second, smaller petri dish. There, he searched briefly and focused the microscope on six small circles.

Rea leaned back in his chair. 

All of them were eggs. None of them were fertilized. 

Rea shook his head and sighed. The Painters didn’t say much. 

“I’m bummed,” Brent said.

“You got too excited,” Stephanie said.

Just days ago, Rea had flushed 20 beautiful embryos from a cow, he said. The next cow he flushed delivered 12. The next, seven. He was doing well, he said, well above average. Today, that changed. It always does.

“You always get back to average eventually,” Rea said. 

Rea cleaned up his workstation and packed his equipment back into his pickup. 

The Painters still had cows ready to receive fertilized embryos, and they had bought frozen embryos from other cows, so they might as well do it, they said. Rea transferred the embryos in the ripping wind, strands of saliva arcing from the cow’s mouths.

When he finished, Rea shook hands with the Painters.

“I wish that would have gone better,” Rea said, “but you’re due for good luck now.”

Brent nodded. “We got the bad luck out of the way, right?”

It won’t be the end of embryo transfer for the Painters, Brent said. They have different cows that they can try next year. But it was a disappointment. 

“You put all that work into it to get nothing,” Brent said. He stood watching a herd of cattle grazing in the distance. They’ll try some older cows next time, he said. They have a lot to choose from. They’ll try again. 

“Next year,” he said.

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