Dairymen are starting to realize the advantages of adding grasses to their alfalfa-corn silage rations – to provide more effective fiber and reduce energy levels.

But there’s a learning curve and a change of mindset that growers need to overcome when growing, harvesting and storing grasses, says Geoff Brink, USDA-ARS research agronomist at the U.S. Dairy Forage Research Center in Madison, WI.

“Very few farmers would think about cutting alfalfa according to the way it was done in 1940, but those are the standards that we still apply to cutting grass hay or grass for silage,” he maintains.

“Traditionally, grasses have been harvested when yield is greatest. A producer will harvest six or seven weeks after growth starts in spring, so the grass is fully in seed. You have really high yields, but the quality is extremely poor.”

That grass isn’t suitable for modern dairy production, he says.

“We would like to see grasses harvested at the boot stage or very early heading.”

A cutting height of 3-4” is crucial if growers expect the grass to stay viable for three or more years, Brink says.

“Our research does show that, the closer you cut to the ground, of course, the more biomass you’re going to harvest and you get more yield. But you negatively affect the persistence of the grass. This may not be an issue if a farmer is going to rotate his grass into another crop in two years. If he intends to keep it for three or four or five years, then it would behoove him to harvest at a higher residual stubble of 3-4”.”

Growers should treat grass as well as they do the queen of forages – alfalfa, he adds. That means going to the same lengths to prepare good seedbeds and using quality seed at appropriate seeding rates. That adds to establishment costs, which may lead growers to keep the stands longer and maintain higher harvest heights.

Grasses need nitrogen (N), either from manure or commercial fertilizer. If using manure, growers should be aware that it has a lot of potassium (K) and increases the K level in grasses. High-K grasses fed to close-up cows can make them more susceptible to milk fever. Tall fescue and timothy contain less K than other species, but all grasses contain more in spring than later in the growing season, Brink says.

“It’s recommended to have manure put on after the first crop is cut. Apply it in the summer or fall.”

N fertilizer gives the most bang for its buck if applied in spring when growth rate is faster, he says. But it can be applied anytime in the season, usually around 60 lbs/acre in a single application and up to 120-180 lbs/acre for the year, depending on the climate.

Growers with access to urea as an N source should apply it shortly before a rain, he suggests.

Making good grass hay can be difficult, Brink says. “It poses the same problems as making good alfalfa hay does – getting a three- to four-day window of good weather.

“But grasses tend to dry faster because the windrows are not as tight. So a producer has to be a little more aware and not let grass get too dry.

“We had an interesting experience making meadow fescue hay. Meadow fescue has a very soft feel to it and our farm manager kept saying, ‘This is too wet to make into hay.’ Finally, he decided we’d better test it, and found that it was well past time to make hay. Producers used to making alfalfa haylage may not realize how fast grass dries.”

Ensiling grasses is challenging until producers get used to the crop. “It’s a lot different from corn silage. Like alfalfa haylage, grasses should be ensiled at 60-65% moisture, but, if necessary, can be put up a little wetter because it has a somewhat lower buffering capacity.” Just beware of potential clostridial problems, he warns.

Proper compaction is essential. “It can be said that it is more challenging (to store grasses compared to alfalfa haylage). At the same moisture, and with the same amount of packing, the density of grass silage is less than that of alfalfa, so there’s potential for spoilage or low density and all the issues that come from low density.”

If making grass baleage, producers should wrap it as soon as possible. “The more quickly you wrap that bale of high-moisture hay, the higher quality it will be. And use a minimum of 6 mils of plastic.”

Brink will speak at a Dairy Forage Toolbox Seminar session at World Dairy Expo, to be held Sept. 28-Oct. 2 in Madison. His talk, “Growing Grasses for Dairy Rations,” will begin at 1:30 p.m. Sept. 30 in the Arena Building at Alliant Energy Center.

Besides harvest, fertilizer and storage management, he’ll discuss the benefits of growing grasses and incorporating them into dairy rations. (Read our November 2008 story, “Grass May Help Balance Hot Dairy Diets.”)

The importance of selecting the right species and varieties will also be a part of his talk.

“People won’t go and buy an unnamed variety of alfalfa or corn; they know exactly what the variety or hybrid has in terms of its attributes and traits. We’d like to get people thinking that way about grass species as well.” (See our August story, “Grass Choices Are Crucial.”)

Brink will also cover how the nutritive value in grasses changes from spring to summer to fall and how producers can best manage the crop to retain quality.