June 20, 2024

Growing annual forages extend grazing season for cattle herds

Filling the grazing gap

DUBUQUE, Iowa — Extending the growing season is one of many benefits annual forages can provide to cattle operations.

“Winter, spring and summer annuals are all helpful in filling the grazing gap and they provide very good quality feed in times when we don’t have good grazing resources,” said Denise Schwab, beef field specialist for Iowa State University Extension and Outreach.

“Cool season perennial pastures work really well in the spring and pretty good in the fall, but during the summer slump there is almost no growth,” said Schwab during a presentation at the Driftless Region Beef Conference, presented by University of Illinois Extension, ISU Extension and Outreach and University of Wisconsin Extension.

Annual forages can help with weed reduction, especially with winter cover crops, Schwab said.

“If you’re fighting corn rootworm problems, sorghum and summer annuals are a way to break the cycle,” she said.

For winter annuals, rye is an option for the early grazing season.

“If we need early grazing, cereal rye is the first to break dormancy, and when it shoots up, it explodes,” Schwab said.

“Triticale will be slower to come up, about a week later than the rye,” she said. “But it won’t mature quite as quickly so it extends another week or two in the spring grazing time period.”

A study in Iowa compared several winter annual crops including cereal rye, grain wheat, forage wheat and triticale.

“We didn’t see much advantage of the forage wheat compared to the grain wheat,” Schwab said.

“The crude protein of the forages was in the mid to high teen range and the energy was around 60%,” she said. “Sixty percent TDN is more than adequate for most cows and the teens for protein is also adequate so the winter annual crops for the most part are pretty good feed quality for cows.”

For another project in Iowa, the researchers interseeded into old pastures a mixture of purple top turnips, vetch, radish, flax and oats.

“We did this for five years and turned cows out to graze in November for about 30 days with one cow/calf pair per acre,” Schwab said.

“For studies at Iowa State related to cover crops, one year out of five is a bust, one year is a boom and three out of five are decent,” she said. “One year we got pretty decent oats and a couple years we didn’t get many oats, so it was heavy brassicas.”

Calves were born to the fall calving cows in August and September.

“The cows lost weight from November to December, but the calves on the cover crops were almost double in weight compared to calves in a feedyard,” Schwab said. “And it was really interesting that these calves at weaning time were still heavier than their counterparts in the feedyard.”

When grazing summer annuals, Schwab said, they must be strip grazed.

“Limit the amount of feed the cattle have so you don’t have excess waste,” she said. “If you have 20 cows on a 50-acre field and you turn them loose, you’re going to lose at least half of the forage from trampling. But if you strip graze what they will eat in a day, there will be a lot better utilization.”

If the cattle are going to be off the field in five days, Schwab said, a back fence is probably not necessary.

“But if they’re going to be on longer than five days, make sure to have a back fence because as the plant starts to regrow, the highest concentration of prussic acid is in the new growth shoots of sorghum-sudangrass.”

As cattlemen develop a grazing plan they could plant a spring annual, follow it with a summer annual and then a winter cover crop.

“You can get three forage crops off an acre in a year,” Schwab said.

“You have got to be able to put fencing out and you got to make sure the cows see the fence,” she said. “If the cows can’t see the fence, they’re probably going to walk through it.”

In addition, the cattle need access to water and the water systems need to be functional during the winter.

“Maybe you can put tanks in fence lines between pastures and fields that you might want to graze so the cattle have access off both sides,” Schwab said.

“I’m not saying we should put annuals on every acre because you don’t need a lot of acres since they produce a high tonnage yield,” she said. “Maybe that little four-acre field that is a pain to farm is a candidate for you to look at for an annual grazing project.”

Martha Blum

Martha Blum

Field Editor