Cover crops don’t just improve the performance of crop fields; they also make excellent forage for cattle.

Nancy Peterson, a veterinarian and co-owner/general manager of Plum Thicket Farms in northwest Nebraska, shared her experience grazing cover crops and annual forages during the Range Beef Cow Symposium last November in Loveland, Colo.

Plum Thicket Farms utilizes approximately 4,000 acres of native range for grazing and farms 2,300 acres. Peterson and her husband manage the cattle, while their son handles the farming. Nearly 75 percent of the farm ground is dryland acreage. Annually, 14-16" of rain can be expected.

“Pasture is by far our most limiting factor,” Peterson says. Despite that limitation the family farm has been able to graze cattle 11 months out of the year.

To obtain extra grazing, annual forages and cover crops have been a vital component of the cattle operation.

The 286-head cow herd calves on ryegrass in May. Prior to calving, during the winter cows graze on swathes of forage sorghum. Crop residues are added into the mix on the family farm ground, along with a half-section of leased corn stalks from a neighbor.

All of the steer calves are backgrounded until March on sorghum swathes supplemented with dried distiller’s grain. The heifers go out on corn stalks for the winter and receive 1 lb. of dried distiller’s grain per day.

In the summer of 2015, 500 head of stocker steers were grazed for three months to take advantage of annual forages.

Grazing forage cocktails through cover crops has been an excellent way to increase productivity of fallow fields following a planting of wheat or oats.

Rye Time

“Grazing rye in May is a no brainer. It is wonderful to calve on,” Peterson says.

There are challenges with the rye though. The grass tends to grow all at once and Peterson says, “It can get rank pretty easily.”

Peterson recommends swathing rye when it starts to head out to help lengthen the amount of grazing. The Gordon, Neb., family operation has experimented with two cutting heights: a short cut near the ground and the other leaving 4-5" of stubble.

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Swathing rye has helped make it more palatable and productive to graze. Photo by Nancy Peterson

Both heights yielded nice regrowth, but the short cut rye did take a week longer to grow to an appropriate grazing length.

“The swathes were very palatable and full of good nutrition,” Peterson says. Dryland rye tends to handle 0.97 animal unit months (AUM) per acre for Plum Thicket Farms.

Right after the rye a warm-season forage cocktail could be planted.

Sorghum Savings

Since 2005, Plum Thicket Farms has been grazing sorghum swathes. A brown, mid-rib forage sorghum variety is used with cutting occurring just as the head begins to emerge from the sheath.

The sorghum swathes offer flexibility in grazing, and cows feed on it throughout the winter, even when covered with snow. Backgrounding calves works nicely on the forage sorghum swathes, too.

“It is very reliable. We’ve never had more snow than the cows could dig through,” Peterson says of wintering with sorghum swathes. Grazing sorghum swathes creates an expected production of 3 AUM per acre.

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Sorghum swathes are grazed through much of the winter at Plum Thicket Farms. Photo by Nancy Peterson

Calves typically gain 2 lb. grazing on the sorghum, along with some distiller’s grain added to the ration. “It ends up being a very inexpensive cost of gain,” Peterson adds.

The total cost to run cattle on sorghum swathes comes to $148.76 per acre after accounting for costs like land, seed, spraying, fertilizing, planting and swathing. Peterson has calculated it out further and found the total cost per head each day is only $1.38, coming to a cost of gain at just $0.69 per lb.

Both as a veterinarian and a producer, Peterson recommends waiting five days after a hard freeze to start grazing the sorghum swathes to avoid problems with prussic acid. Be sure to test for nitrates as well.

Mob Rules

Cool and warm-season forage cocktails were used this past year for mob grazing on the dryland fields.

This past year brought abnormal moisture at 25", nearly 10" above average. It made for a great year grazing, but isn’t what producers should expect when running cattle on a cover crop.

“I have to say it is not for the faint of heart,” Peterson cautions. “You’ve got to have a population that can flex because it is entirely dependent upon getting adequate rainfall.”

Developing yearling heifers or running your own stockers allows you to pull cattle off should conditions call for it.

If you’re custom grazing stockers, Peterson says you need to have a contract specifying cattle can be removed should a weather anomaly like drought, hail or fire occurs.

“The reason we use forage cocktails is they are more drought tolerant. The more diverse a plant population the more they help each other,” Peterson says.

Legumes should be in a forage cocktail to fix nitrogen. 

Brassicas like turnips, collards, radishes or canola should be in the mix to help make phosphorus more available to other plants. Brassicas aid in feeding soil bacteria and increasing soil biomass, too. Collards are the brassica of choice at Plum Thicket Farms because they aren’t as dangerous to graze.

The forage cocktails generated 3.24 AUM per acre for a good moisture year. Peterson would more commonly expect to get 2.25 AUM per acre.

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Rotational grazing sends cattle through fields up to three times. Cattle won’t be turned out until oats reach 12” in height and are pulled off when forages are 4” tall. Photo by Nancy Peterson

It can be easy to go over budget with a forage cocktail, so make sure you watch seed cost, Peterson adds.

Costs for the cool and warm season cocktails seeds used by Plum Thicket Farms have been from $22-$27 per acre. A total cost for planting the cool season cocktail was $125.86 per acre last year, while the warm season cocktail was $6.45 cheaper.

Despite the savings, warm season cocktails are not a replacement for native range during the summer. Growing a warm season cocktail in early fall might be a better alternative.

“You’re not going to get rich doing this, but you’re farming for the future,” Peterson says. “There are a lot of unmeasurable benefits from including livestock in a farming rotation.”

Soil at Plum Thicket Farms is sandy so the soil profile has been low on nutrients. Thanks to the inclusion of annual forages for grazing in the crop rotation, soil structure has improved as well as the organic matter. Soil phosphorus levels are increasing steadily and may not require supplementation much longer. Nitrogen application will be required for the next several years.