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Supplement hay now for more grass later

March is a month of forage anticipation. Even late “spring” calving is wrapping up. Lactating mama cows need the best nutrition of their reproductive cycle. And, if hay supply is to become sparse or run out, this is the month to turn out to pastures.

Yet, most grass is not there to meet the demand, especially in northern counties.

March becomes a month of quandary. “Most likely this is the time when cows need supplementation,” says Rob Kallenbach, a University of Missouri Extension forage specialist. “We know that shorting the milk supply to a new calf has lifelong impact on growth.”

Key Points

The spring transition from hay to grass takes management.

Early overgrazing of livestock can harm growth throughout the year.

Leaving 2.5 inches of grass residual is a key rule to follow.


Spring is the time to revive grazing management skills. “With hay short, and green grass tips showing in the pasture, there is an urge to turn out the cows. Let the grazing begin.”

Whoa, not so fast. Some purchased feed can help the calves and save the pasture. Just as the calves benefit from early nutrients, early nipping will harm pasture grasses. Production will be altered all season. Protecting new growth can pay off later in the year.

The plant physiologist in Kallenbach says to hold off turning in grazing livestock until the grass is 8 inches tall. Well, maybe early at 7 inches. Lush pasture keeps cows from working so hard to get a mouthful of grass.

Practice patience

The practical grazier in Kallenbach knows that no one wants to wait that long for first grass. But, 4 inches of growth is his lowest starting point.

“Whatever the height of grass at turn-in — 8 inches or 4 inches — the residual height of 2.5 inches must be maintained. On short grass, that means in and out fast.”

There are debates about residual height, Kallenbach admits. “That 2.5-inch mark is a good target for cool-season grasses in Missouri, year-in and year-out. Turning in the herd for three days will nub a pasture down to where it takes too long to recover. Have enough leaf surface area for photosynthesis to work. Otherwise the regrowth must come from root reserves.”

Protracted overgrazing early will cause lifelong harm to a pasture. Mixing hay feeding and grazing in the same paddock just doesn’t work well. The cows will continue grazing the new grass until it is all gone. After doing their damage, they return to the hay.

Better alternative

Hay and supplement can continue to be fed in a sacrificial paddock, just as graziers will sacrifice a paddock in a wet, muddy spring when cattle tear up paddocks while grazing.

“Graziers that have large enough alleyways can unroll baled hay there,” Kallenbach says. Cows can be grazed eight to 10 hours of the day then brought back to the hay.”

A couple of paddocks can be used early and not hurt the season-long production in the rotation of a management-intensive grazing system. However, turning in at 4 inches on a continuous grazing system will hurt production.

“Remember, that when warmth returns, moisture is available and sunshine plentiful, the paddocks grow more grass than the herd can consume. Too much grass gets over-mature and loses quality,” Kallenbach says.

On the first rotation, paddocks must be monitored closely. Grass is resilient, Kallenbach says. “Grass forgives some abuse, but not season-long abuse. It’s OK to make a mistake if you learn from the mistake.”

Use a boot as measuring stick

Not many will remember to bring a grazing stick for measuring grass for that first turn in this spring. To improvise, put a marker on your boot at the 4-inch height — this will keep you from overestimating how tall the grass is at first turn-in.

Later, mark on your boot at 2.5 inches from the ground. When growing green grass is no longer above that mark, take the livestock out.

MU Extension forage specialist Rob Kallenbach picked up the boot tip in New Zealand, where the Kiwis mark their Wellies (boots) to guide their forage management. “Just put a piece of duct tape on the side of your boot,” he says.

Hold the nitrogen fertilizer

When grass is slow to start, too many grass growers think a shot of nitrogen will help.

“No doubt, 50 pounds of nitrogen will give a great response,” says Rob Kallenbach, MU Extension forage specialist. “But it also throws grazing out of balance later in the season. By May, there will be more grass than the herd can consume.

“Nitrogen fertilizer in spring is never a good idea,” he says. “I may upset my friends at the farm service companies, but that’s true.”


This article published in the March, 2011 edition of MISSOURI RURALIST.

All rights reserved. Copyright Farm Progress Cos. 2011.