Forage basics for pastured hogs

by Sonja Heyck-Merlin

“There’s not a lot of recent research information on pasturing hogs,” said David Hartman of Penn State, where he works as a livestock Extension educator. “This is because over the last few decades, the swine industry has become more consolidated with much more production in confinement systems, and not nearly as much pasture.” Use of forages for hogs diminished in the early 1950s when synthetic vitamins became widely available. Prior to that, hogs needed access to some pasture to obtain those vitamins.

Because of the lack of current research, Hartman led participants into the past in a webinar sponsored by Penn State. “Think about it from the perspective of the farmer 70 years ago with less mechanization. Imagine having to gather up all that bedding, store it in a barn and then shovel out all that manure and get it into fields. There was no such thing as skid steer loaders or liquid manure systems. We can learn some things from what farmers did 70 years ago and try to bring that back into usage for people interested in pasturing hogs,” he said.

Hartman gleaned historical information on hog pasturing from two books – the USDA Yearbook from 1948 titled “Grass” and the classic “Morrison’s Feed and Feeding.” These resources talk about four primary pasture systems that were used during this time – permanent pastures, rotation pastures, annual pastures and hogged down pastures. (Hogging down refers to the practice of turning hogs into fields of standing crops such as corn.)

Historically, Kentucky bluegrass and white clover were the primary species in permanent pastures. “Bluegrass is a sod-forming grass that can survive close grazing. It’s able to spread and form a sod. White clover, a legume, is very similar in its growth habits,” Hartman said.

Rotation pastures were typically seeded with alfalfa, red clover, orchard grass and brome grasses. According to Hartman, these tend to be shorter-lived perennials providing quality forage for only three to five years. When the desirable species in these rotation pastures disappeared, farmers would plow and reseed following a set rotation.

Hartman suggested the use of grazing alfalfas rather than forage varieties, which have high crowns susceptible to damage by foot traffic. According to “Morrison’s Feed and Feeding,” alfalfa should carry eight to 10 full-fed hogs per acre throughout the summer with no danger to the stand.

Temporary pastures included annuals such as rape, soybean, sudangrass, rye, oats, wheat, barley, Italian ryegrass and peas. Hogging down crops included corn, soybeans, sorghum, small grains and sweet potatoes.

Rape, one of the most common forage brassicas, was typically planted in mid-summer for autumn grazing and was often interplanted with oats, barley and/or peas. When grazed wet, however, rape can cause photosensitization, with Hartman warning, “White hogs are more sensitive. Any areas that are low in pigment may get sunburned and blistered.”

Regardless of forage type or how these forages are managed, Hartman stressed that hogs have digestive systems more similar to humans than ruminants. “The point is that the hog hasn’t evolved to the point where it’s good at using forage. If you’re going to use pasture, you’ll still need to look at using other types of concentrated feeds to supplement hogs on pasture. You also need to be thinking about the pasture quality, not so much quantity,” Hartman said.

Plant maturity impacts forage intake and digestibility. Plants become higher in fiber and lower in protein energy as the plants mature. Hartman said that if you’re going to use these forages for hogs, it’s important to graze them during the earlier part of the cycle when they are in a more vegetative state and have higher nutritional value.

According to “The Pork Industry Handbook,” which Hartman referenced, the stocking rate for hogs on pasture is four to six gestating sows or 10 to 12 growing hogs per acre. “If that were me, I would probably start with two or three and see how that goes. If it goes well, it can be bumped up over time,” he said.

Hartman also said it’s important to provide access to clean water, shade and/or shelter and minerals, and he suggested finding a breed that’s readily available. “You don’t want to have to drive halfway across the country to find replacement breeding stock,” he said.

For producers interested in experimenting with raising hogs on pastures during the grazing season, Hartman concluded with some words of advice: “Keep it simple. I have seen these kinds of problems in agriculture that sometimes as we get more information we tend to make things more complicated than they need to be. We’ve got to be able to walk before we run.”

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