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The Untold Story Of How Eggs Make Your Bacon

Amy Mayer
Harvest Public Media
Liquid nitrogen is used to freeze and store thin plastic straws containing boar semen. By vacuuming up some of that nitrogen gas, you can see the frozen stash.

When a man places 40 dozen eggs on the conveyor in the check-out line at the grocery store, it begs the question: What’s he going to do with all of them?

This happened to Kim Becker in Ames, Iowa. The man’s answer left her so gobsmacked, she posted it on Facebook:


Swine Genetics International (SGI) is about 20 minutes from that store.

“That could have been me or it could have been a number of people here,” SGI Chief of Operations Michael Doran says about the supermarket run.

Amy Mayer
Harvest Public Media

SGI has three barns that can house up to 180 boars, from which workers collect samples a couple of times a week. Doran says that semen is shipped around the world — sometimes fresh, sometimes frozen. But the semen is fragile, so to preserve its viability, companies like SGI combine it with a solution called an extender.

“The whole purpose of an extender is to extend the life of the semen,” says Benny Mote, a swine extension specialist at University of Nebraska-Lincoln. “It gives nutrients to the sperm so they will keep swimming,” and it dilutes the semen so one collection can be divided into many doses.

Mote says most companies ship fresh swine semen because it doesn’t hold up well when frozen and then thawed.

In the early days of artificial insemination, he says, extenders often contained egg yolks. SGI still does that, though most of the handful of companies supplying the $191 million annual domestic market for boar semen have switched to other ingredients.

Al Wulfekuhle, a longtime hog farmer and breeder in the northeast Iowa town of Quasqueton, says buying semen for his sows gets him better quality pigs than just letting the animals mate. He is able to work with his genetics supplier to receive sperm with the traits he thinks are most important and without the characteristics he would prefer to avoid.

“The advantage is that they do all the research and collect the top boars,” Wulfekuhle says.

Amy Mayer
Harvest Public Media

Artificial insemination is more practical for other reasons, too, Mote says. First, it means one boar’s semen can be widely distributed, leading to more pregnancies and, eventually, more market hogs. That’s important because U.S. producers send more than 170 million pigs to be slaughtered each year.

“Your labor cost is significantly less by not having to have that many boars around,” Mote says of producers, noting most places now have only one or two boars per farm. “The safety and the welfare of the labor is a lot better because boars are notorious for being mean and causing injury.”

Wulfekuhle keeps a boar around just to provide the pheromones that trigger ovulation in the sows. Otherwise, he buys fresh, not frozen semen, as do most U.S. pork producers, who these days are doing upwards of 95 percent of all breeding with artificial insemination.

Amy Mayer
Harvest Public Media file photo

While some of the basic biology has become obsolete, Wulfekuhle says Mother Nature can still throw a wrench into the best-laid plans.

“You get semen twice a week and you have all these animals ready to breed,” he says, “and then you have a snowstorm or an ice storm.” He’s had to drive to meet a delayed courier in an attempt to get fresh semen while sows are in heat.

SGI says it tries to guarantee the semen will do its job when the time comes, whether it’s shipped fresh or packed frozen into shipping crates with liquid nitrogen. But Doran remains evasive when it comes to why —and how — SGI uses those store-bought eggs.

“There's a foundation, and using a lot of natural ingredients you could find at a grocery store, and it's evolved over time,” he says. “We feel like we've developed and evolved a proprietary recipe that, as we see both in the US and abroad, we have a very high degree of success with.”

Besides that, he adds milk also once was an ingredient in extenders. So be on the lookout for someone buying an inordinate amount of milk at the supermarket in a hog-producing state.

Amy Mayer is a Harvest Public Media reporter based in Ames, Iowa. Follow her on Twitter: @AgAmyinAmes

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