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Disease, contamination, destruction. They may be small in size, but their devastation results in thousands to hundreds of thousands of dollars in lost profit. No one wants to talk about them, but as the cooler weather approaches, there’s no better time than now to discuss rodent control.

Between the COVID-19 pandemic and 2020 weather conditions, rodents are on the rise, says Steve Von Haden, Midwest business manager for Motomco.

“COVID has had a big impact on rodents, especially in big cities. People aren’t going out and moving around as much,” he explains. “The rodents actually feel a little safer because of that.”

Rats and mice aren’t just annoying — they can be dangerous. Because rodents are the No. 1 vector for disease transmission, Von Haden says rodent control should be a critical part of your farm’s biosecurity plan. They transmit over 45 to 50 diseases, 35 of which can be transmitted directly or indirectly to humans and livestock.

“Rodents are reservoirs for diseases like Salmonella, Campylobacter, swine dysentery and Actinobacillus pleuropneumonia,” says Jim Lowe, DVM, director of the College of Veterinary Medicine I-Learning Center at the University of Illinois. “They can maintain infection themselves and carry diseases, which are risks to livestock and food safety, between sites.”

Know your enemy

The most common rodents pork producers battle are the house mouse and the Norway rat. These species are common throughout the country, with the majority in the Midwest. Roof rats are one of the worst rodents to deal with and can be found in the south and on the West Coast.

“Mice are easier to control because they are so curious. Rats are totally different because they don’t like changes in their environment so they adapt to those changes, and once they feel uncomfortable with their environment, they will move,” Von Haden says.

Rats and mice share some commonalities – they both have poor vision and a great sense of smell and taste. They can squeeze their bodies into a very small opening. Rats can squeeze into an opening about the size of a quarter and mice can squeeze into an opening the size of a nickel.

What are the signs you have a rodent infestation? Von Haden says clues include gnaw marks, droppings, odors, runways, rub marks and burrows.

“Seeing rodents is a sign you have a problem, especially during the day, because rodents don’t like to be out during the day when their enemies are out,” Von Haden says.

Pay attention to the walls of your building and look for dust trails. Rodents often travel the same runway because they have poor vision. They urinate to socialize and communicate with other mice along their runways, he adds. Mice typically travel 15’ to 20’ from their nest while rats travel closer to 100’ away from their nests.

Before you can fight your enemy, you must determine who your enemy is. One sign to distinguish is that rats will often create burrows outside your building, Von Haden says.

Why are rodents difficult to eliminate?

Not only do barns and agricultural buildings have a readily available food source at all times, they also have ample water sources and a great nesting area for rodents to have their litters and feel safe. That’s why any agricultural structure or pig barn can become a problem – all the tools are there for them to thrive.

And rodents thrive. Did you know a typical female rodent will have around 50 babies a year? Once those babies are born, they will breed within a month to six weeks. Six months down the road, that could turn into 600 rodents, Von Haden says.

“Quite simply, they are a nuisance. Their reason to be on this earth is to gnaw and multiply,” Von Haden says.

Rodents are a year-round problem; however, fall tends to be the time when people see more rodents on the move, he adds. Generally, people don’t think they have rodents unless they see rodents.

“That’s a mistake,” Von Haden says. “Always assume you have rodents and you should be putting bait out. All agricultural buildings or structures will have rodents of some type. You just don’t want it to get to such high peaks it causes structural damage, diseases and contamination of food sources.”

Being consistent with your rodent control program is key to preventing an infestation of rats or mice on your farm. Von Haden grew up on a farm and understands the challenges farmers face.

“We don’t want to be lackadaisical, but it’s easy to find yourself in that situation,” he says. “Although your goal may be to put out fresh bait and check bait the first Sunday of the month, things happen and get in the way. The tractor breaks down, the pigs get sick, the vet is coming, all these things get in the way. What I’ve learned in my tenure is that the more consistent you are, the less of a problem you’ll have.”

Once a farm gets to a height of infestation, it takes a lot of time producers don’t have, he adds.

Win the battle

“Rodent control is not just putting out some bait and calling it good. You have to do it all, and you have to do it all the time,” Lowe explains.

An integrated strategy to remove habitat, control feed sources and provide a continuous supply of fresh bait is critical, he adds.

Read these tips to rodent-proof your barn.

One of the challenges with fighting rodents in your barn is you must take different approaches with rats versus mice, Von Haden says.

“Mice are more curious and typically easier to control. Giving them a different form of bait will make them feel more comfortable,” he says. “If they don’t eat the bait, try moving it a little. If you move the bait station 10’ to 15’ in another direction, mice are more likely to eat it just because it wasn’t there yesterday.”

Meanwhile, rats are the opposite. They are not curious and do not like change. Rats may take up to 3 days to feel comfortable to approach bait that wasn’t there before.

“They’ll go up to it and say ‘Hmm, that wasn’t here yesterday, what’s going on?’ For rats, it’s important to come at them from different angles. Rats also need to drink water every day, so having a liquid in the bait station helps,” he says.

Burrow baiting is often a successful way to kill rats, Von Haden adds. Placing a big chunk of bait down a rat burrow will likely make the rat feel uncomfortable as it blocks their entrance/exit. Instead, Von Haden suggests using meal bait. Meal bait disperses down into the burrow easier, making rats feel more comfortable to eat it.

“The key to baiting is if the rodent isn’t eating bait, you have to figure out what problem is – is it not fresh enough? Not in right place? Need to switch up your active from a blood thinner to a non blood-thinner? You may need to give them a little different form of bait,” Von Haden says.

“Rodent control is a routine job, 52 weeks a year,” Lowe says. “You can’t get behind.”

Farm Journal’s Pork | Jennifer Shike | August

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