Disposal Plans

David Preisler, CEO of Minnesota Pork Producers Association, speaking at the 2020 Pork Congress.

MINNEAPOLIS, Minn. – African swine fever and foreign animal diseases continue to weigh on minds of pork producers. At the 2020 Pork Congress, over 90 minutes was spent discussing what will happen in the event of an outbreak, how will the disease be contained, cleaned up and keep everyone in business.

Part of the discussion focused on disposing of infected animals.

Beth Thompson, state veterinarian with the Minnesota Board of Animal Health commented that every farm should have an emergency depopulate and disposal plan established on their farm. It is one of those plans on a farm no one wants to talk about, no one ever wants to need it, but should the event arise, it will be important.

“I want to just share some research projects that we're working on from an actual disposal standpoint,” said David Preisler, CEO of Minnesota Pork Producers Association, during the presentation. “One is going on right now at South Dakota State University (SDSU), which started back in June of 2019.”

These research projects are funded by the Pork Checkoff dollars. A portion of the checkoff collected from Minnesota, Iowa, South Dakota and Nebraska is pooled and used to fund this disposal research.

The SDSU research project is looking at shallow burial of hogs in trenches.

“You're going to dig a shallow trench, usually around two-foot-deep and you put some sort of carbon material at the bottom of that trench,” Preisler said.

The carbon material is usually corn stalks or wood chips. At SDSU, they are using both.

The carcasses are laid into the trench and covered with dirt.

At SDSU, there is a site with burial trenches. They have included different measuring instruments to monitor the decomposition of the hog carcasses to determine the effectiveness of the disposal and to ensure it will work to control the virus.

They are monitoring the temperature changes in the carcasses and they are testing the soil at 6, 18 and 36 inches to see if anything is leeching from the burial trench.

“They also set up game cameras to see if there are any predators coming and scavenging,” he said. “There’s pigs that went into some of the pits in June and then there were pigs that went in in November because we also want to look at the cold weather side of this.”

Early testing results, keeping in mind this is an ongoing study, are showing temperatures in the trenches maxing out at 77 degrees, not high enough to kill the virus.

The record rainfall in the area did have an impact on limiting temperature, but it also gave the worst-case scenario on testing virus leeching from the trenches.

Some of the carcasses were treated with Seneca Valley virus and the virus was detected at 6 and 18 inches, but not 36 inches.

Another drawback to the shallow burial method is the amount of land that is required to bury a large herd.

Last August, Preisler and few others went to North Carolina to observe a disposal project being done there. That project involved grinding the carcasses, mixing them with wood chips and then stacking the result in windrows for decomposition.

“This is run through a commercial grinder that's really used more in the tree industry, a horizontal grinder,” he said. “It has kind of the consistency and the look of silage and kind of stacks like silage.”

This project is monitoring all the same things as the SDSU project – temperature, potential virus leeching and predators.

They also set up sensors to see if, during the grinding process, pig DNA was being made airborne. They had one sensor near the grinding site and then more around the site, up to 250 feet away.

“Once the material is spread in a windrow, they take about 18 inches to two feet of clean material (wood chips) and cap it,” he said. “If they have enough of a cover, they haven't seen issues from a standpoint of scavenging.”

The benefit to this method is it requires about half the amount of carbon material, wood chips or corn stalks, and about half the land space as doing whole carcasses.

Pork producers really do need to look at their hog barn sites and determine if they have the land required to dispose of their entire barn full of pigs. If not, they need to talk with their neighbors and see if there is an agreement that can be made. Again, this is one of those plans of actions that everyone hopes will never be needed, but it will be extremely important should it be needed.

“One of the things that we're very confident in, I mean, you're never 100 percent, but you notice that we didn't talk about deep burial,” Preisler said. “The experience has been when you do bury pigs or any livestock in a deeper pit, it may be the gift that keeps on giving from an environmental standpoint.”

The biggest concern with deep burial is leeching into the ground water through tile lines, and the virus, among other things, being spread even further.

The whole point of this research is to create a plan that will contain the virus and eradicate it quickly. These research projects give pork producers a guide to follow when establishing their own emergency depopulation plan.