Brian Mohn counts on corn to fill the gap when his cool-season pastures peter out in the summer heat.

“I needed to find something to carry my cow-calf herd through the summer slump,” says Mohn.

With his wife, Karen, he manages Papa Farm, a 350-acre commercial hay and beef operation near Bethel, PA.

“I was reluctant to take high-priced hay out of the barn to feed my cows in late summer,” he says. “It makes more sense to sell that hay to the local horse and dairy markets and grow something else for my own cattle.”

With input from his county agents, Mohn has learned the finer points of grazing cow-calf pairs on a small field of corn during the summer slump. While the cattle only graze the corn for about three weeks, average season-long calf gains are 2.3 lbs/head/day. This year he's grazing 60 animal units, down from a high of 130.

“Grazing annuals, such as corn, can be beneficial in certain situations,” says Clyde Myers, a Penn State University extension agent in Berks County. Myers and his co-worker, Mena Hautau, have assisted Mohn.

“If producers have limited acreage for grazing, they need the extra production of forages in mid- to late summer when cool-season grasses slow down,” Myers says. “It also gives them a measure of safety in case of dry weather because they'll have an additional source of feed to rely on.”

The extension agents have researched corn grazing on cooperating dairy and beef farms, with positive results.

“When dairy cows grazed corn, their production stayed the same,” notes Myers. “However, there was more corn wasted with the dairy vs. the beef cattle. That's probably because dairy cows are fed other feeds to keep their production up.”

Mohn fall-seeds a wheat and rye mixture on the field targeted for corn the following year. It's grazed once before winter and once or twice in spring, then is killed with 2,4-D. He plants a 120- to 124-day hybrid between mid-May and mid-June, depending on the weather. He plants 15" rows with a no-till drill, aiming for a population of 40,000 plants/acre.

He says no-till saves money. “If I plowed and disked the field, my costs would be way too high.”

He starts grazing the corn when it's at the pretassel stage, from late July to mid-August.

About 10 a.m. every day, he gives the cattle access to a 25 300' strip of fresh corn, using a portable electric fence. Next to the corn is a small alfalfa-orchardgrass pasture that the cattle can also graze.

“They have their choice between the alfalfa-orchardgrass pasture or the corn, but normally they go into the corn first to eat and then head to the other side to loaf around and chew their cuds.”

Giving animals access to both types of feed is important, says Penn State's Myers. “Then there's some continuity in the animals' diets.”

Mohn drives his ATV through the field to clear a path, then strings the wire through the path. “That knocks some stalks down just enough so that they can see the electric wire. I keep it good and hot, so they respect it.”

By mid-September, when night temperatures are cooler and his perennial pastures are growing again, the corn's gone.

Mohn has used grazing-specific and silage hybrids. He prefers silage corn because the seed is less expensive.

“We've analyzed samples from both types for nutrient content and the grazing corn had a little bit higher sugar content,” he reports. “But in my book that benefit didn't outweigh the higher cost.”

Loose manure hasn't been a problem. “I've seen it a lot looser on lush, grass pasture than it is on the corn, which was contrary to what I originally thought.”

He adds: “Timing when you're going to need the corn is probably the hardest thing to predict because the amount of rainfall we get changes. If it's not too dry here, the pastures stay productive longer.”

Sorghum-Sudangrass Shines

Sorghum-sudangrass is a good choice for battling the summer pasture slump, says Clyde Myers.

“In some ways, it beats corn,” adds Myers, an extension agent for Penn State University in Berks County. “Sorghum-sudangrass can be grazed several times vs. just once for corn.”

It has other benefits, too. “We had a drought two years ago and the only thing that grew was sorghum-sudangrass,” he says. “That's a big advantage it holds up well under dry conditions, whereas corn needs moisture. Plus the seed's cheaper.”

In Pennsylvania, sorghum-sudangrass should be seeded in early to mid-May, he advises. “It will really come on strong when the weather warms up.”

Grazing can begin as early as late June. Depending on the weather, the crop can be regrazed every 20 to 30 days. “But once the temperature hits 50 degrees usually in September it shuts right down.”

If the forage is grazed when less than 30" tall, it's fairly nutritious, with crude protein percentages running in the high teens, says Myers.

“Even with dairy cows, if you get it at a young age, it's pretty good. We haven't seen milk production drop. We've found that nitrate and prussic acid poisoning have not been a problem if sorghum-sudangrass is grazed this young. However, caution should be taken when grazing it after rain following periods of dry weather.”

He encourages dairy and beef producers to continue to graze other pasture species while grazing sorghum-sudangrass.

“Then they're not changing the rations as drastically,” he says.
— Ann Behling