SWIFT CURRENT, Sask. — Corn grazing continues to gain popularity in Western Canada but producers are still learning how best to manage the system, says beef researcher Bart Lardner.
“It’s a learning curve,” he said after a presentation at Foraging into the Future. “It’s not going to go away. The adoption rate is ramping up every winter.”
Lardner said corn is attractive because it produces 2.5 to three times the biomass per acre of other feeding systems. However, a gap exists between producer knowledge of how to best manage it without negative effects on rumen digestibility.
“Typically in our winters we’re going to have to supplement to some degree on whatever extensive system it is and all of a sudden we have a crop that’s meeting or exceeding the nutrient requirements of a beef cow in first and second trimester,” he said. “Yes, it’s a little low on protein for that soon-to-calve cow but I think it’s all about managing access to the crop and controlling new allocations.”
He and others recommend three to four days of grazing in an area to moderate the “massive” starch and energy intake from the cobs with fibre intake from the stalks, which will buffer the rumen.
Corn should be grazed at the half-milk stage and cows not familiar with the crop should have access to supplemental fibre.
“You’re going to get about 50 percent or less starch and 50 percent fibre,” Lardner explained. “The fibre will mitigate the crop in rumen pH from the starch.”
The cows should be exposed to a starch diet through some grain supplementation for seven to 10 days before they go into the corn.
And, they should not be hungry when they go in.
Lardner added that some producers are planting varieties that need about 300 heat units more than they will actually get. That way, the corn is only at the half-milk stage at the first killing frost.
Western Canadian producers have generally been grazing the whole plant, while in the United States, producers usually grow the corn, harvest the grain and then graze the residue.
“Maybe you take it as snaplage, which is just taking the cob, the stover and part of the stalk, and then grazing that residue,” Lardner said. “That (snaplage) is really good as an ensiled product.”
He predicted that producers will move to a combination of systems to offer more options.
Producers who take off the grain and graze the residue will have to add an energy supplement during a really cold winter, whereas those who graze the whole plant will already have that energy available in the cobs.
“We’re going to blend the two,” Lardner said. “It’s going to happen.”