The Iowa State University beef teaching farm has started using swath grazing for its cow herd and has learned it can be a more economical option for winter grazing.

Jennifer Carrico

April 14, 2023

5 Min Read
Cows in snow-covered field eating hay in front of wire fence
WINTER FEED: Cows are given more swaths every two to three days by moving the hot-wire fence to expose more of the available forages. Photos by Garland Dahlke

Many different options are available for grazing cattle, but very few work in the winter months in Iowa due to snow cover. However, Iowa State University (ISU) started using swath grazing on its beef teaching farm four years ago with success.

ISU scientist Garland Dahlke says the use of swath grazing saves time and money when looking for a winter feeding strategy for cows. “This is the fourth year we have used swath grazing at Iowa State. We have found a combination of sorghum-sudangrass and millet works best,” he says.

Oats (a cool-season cereal) are planted in the spring, followed by sorghum-sudangrass plus millet (a warm-season annual) no-till planted in June into the oat stubble, which has been grazed. The warm-season annuals and oats are then harvested as hay in late July. Regrowth after that cutting is used for winter swath grazing. ISU allows the grasses to grow until the first part of December, when it is mowed and raked just as if to be baled. Cows can start grazing soon after raking. “We allow 80 cows to graze on 36 acres from mid-December until mid-February most years,” he adds.

Cows in field with dry hay

Dahlke says they have learned swath grazing is best for non-lactating cows in the second or third trimester of pregnancy, but it can work for late-lactating cows if the right forages are used. “Bred heifers and yearlings are less aggressive eaters, so we avoid putting them in a swath-grazing situation. Cows in early lactation and young calves require more nutrients, and we avoid those groups as well.”

Challenges of swath grazing

The biggest challenges seen with swath grazing includes machine accessibility, fences and water. Machinery, especially hay cutters, isn’t usually used in the winter months. Dahlke says it is very important to make sure the cutter is properly maintained to be able to work in colder weather. He suggests putting the machine inside a heated area, if possible, to be sure it will work properly.

Finding the right kind of fencing to use can be a challenge as well. The cattle shouldn’t be turned out into the entire field all at once, and thus, hot-wire fencing is usually the choice. At ISU, staff use polywire fence with reels to move it, which they say is very quick and easy to move.

Water access can be a challenge in the wintertime if the field doesn’t have access. Dahlke says cows will get water from snow when there is moisture available; but when precipitation is low, water intake is about 3 gallons per cow per day. A good water source must always be available, but consumption can vary.

Truck driving on field of windrows

Knowing the quality of the grasses in the swath can also help to know how much supplementation may be needed prior to calving. ISU supplements with corn gluten feed three times per week for about the last three weeks of gestation, with calving starting in mid-March.

Dahlke says the cows will usually eat the sorghum first, likely because of the sugar present in the plant. The millet will hold nutrients longer, which is why it is added to the mix.

“It’s most important for producers to figure out what forages will work in their area. Warm-season grasses work for north-central Iowa, but in Canada they use more cool-season grasses,” he says. “Legumes could work, but they tend to drop leaves faster.”

Solid benefits

Cow health doesn’t seem to show much difference from when cows are fed in a lot or hayed in a pasture, but the cows do stay cleaner and have clean udders and underlines, which helps with calf health.

Forage utilization is increased over stockpile grazing but may be a bit lower than feeding harvested hay; however, the cost is where swath grazing shows a benefit, according to ISU research. “We have a cost of $0 per acre when swath grazing and 70% utilization. Harvested hay has an 85% utilization, but costs $26.96 per acre more, and intensive, stockpile grazing only has a 40% forage utilization and costs $27.43 per acre more when comparing at the same tonnage,” Dahlke says.

There is a cost when it comes to planting the forages, but it is minimal, as he says the most expensive of the past few years was a $1.11-per-acre cost. “Year in and year out, it’s more economical to use swath grazing than conventional farming on farm ground where cows are present,” Dahlke adds. “We are also looking to see if cornstalk swathing might work on shorter-maturing corn, like what is used in Canada. This could provide a good source of winter feed as well.”

Working swath grazing into a crop rotation is something Dahlke says could work for many producers, and they may find it works very well in their system. Some additional surprises they have found at ISU are no damage to the fields as the cows spread out to graze, and utilization was not affected by the depth of snow or ice.

Cows will work to get their food as long as they know it is there.

About the Author(s)

Jennifer Carrico

Jennifer Carrico of Redfield, Iowa, runs a small cow-calf operation with her family. She is a former editor of Wallaces Farmer.

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