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Getting maximum nutrition from mixing alfalfa, grass stands

Gary Nowaczyk Published on 15 May 2013

Mixing grass with alfalfa stands has long been a popular choice for farmers who produce dairy feed.

Many opt for mixed stands because it offers benefits, such as better digestibility, when used in fields where cattle graze or for making dry baled hay.

While grass provides nutritional advantages, some experts are now suggesting that grass with alfalfa can complicate dairy cows’ diet and crop management practices.

The traditional line of thinking has been that grass helps increase digestibility, but changes to feeding systems have called into question the need for grass mixed with alfalfa.

Mixed stands also present management issues for farmers due to timing challenges for planting and cutting.

Dietary considerations for choosing what to plant. The biggest consideration for farmers who plant alfalfa
and grass is the variability it can create in a feeding program (see Table 1).0513fg nowaczyk tb 1 full

“The reason people get excited about planting grass and alfalfa, from a nutrition standpoint, is that grass tends to have higher fiber digestibility than alfalfa,” says David LaCount, manager of nutrition and technical services at Purina Animal Nutrition.

“Grass can be a more digestible forage, but the problem is, when it is mixed with alfalfa, most farmers are going to harvest when the alfalfa is ready.”

At that point, LaCount cautions, farmers will have a mature grass that has more fiber and a lower fiber digestibility than if it had been harvested at its optimum.

Fiber is an important factor for nutritionists to consider in their diet recommendations. Nutritionists evaluate relative feed value, relative forage quality and the fiber level along with the digestibility of the forage to understand how the feed will perform.

If a diet contains too much fiber, it can limit dry matter intake and prevent dairy cows from producing at their optimum levels.

And when mixed stands are harvested with grass that is too mature, fiber levels of the haylage can often be higher.

When grass and alfalfa are grown properly together, the combination can play an important role in diets by lowering the non-fibrous carbohydrate content, which elevates sugar and starch levels when the percentage is too high.

Many farmers feed corn silage, but as Professor Dan Undersander at the University of Wisconsin warns, corn silage can present problems.

“Farmers who are feeding a high percentage of corn silage often have a problem keeping the ration of non-fibrous carbohydrate below 40 percent,” says Undersander.

“Grass and alfalfa is an option for people who are having trouble staying below 40 percent non-fibrous carbohydrate.”

Growing grass and alfalfa together
Farmers interested in growing grass and alfalfa together should look closely at their planting practices.

“There are two basic ways of seeding,” Undersander says. “One is to mix the two together at seeding, which a lot of farmers have done.

The other option is to seed the alfalfa first and then to seed the grass later. This would let farmers use Roundup Ready alfalfa if they wanted and get a nice clean stand of alfalfa.”

Undersander says seeding the alfalfa first, followed by grass, provides farmers greater control over the percentage of grass in the stand. In addition, mixed stands provide some resistance to winter injury and winterkill.

Managing grass and alfalfa
When farmers grow grass and alfalfa together, a successful crop depends on the varieties of grass they are using and when they are doing their first cuts.

Forage grasses can introduce a level of variation when planted with alfalfa. A species such as orchardgrass heads out earlier, while alfalfa might still be in an immature phase.

But a grass such as rye might not be mature enough when alfalfa is at its optimum.

“Grass variety selection is as important as selecting cattle for your herd,” says Undersander.

Each grass variety can alter the cutting schedule and affect the quality of the crop because of the varying maturity rates.

“First-crop alfalfa can become jeopardized when grass matures more quickly than the alfalfa,” says Randy Welch, alfalfa and forage agronomist with WinField. “If the grass is too mature, it can lead to a higher fiber content in the crop, impacting dairy cows’ intake.”

Farmers who grow mixed stands should aim to cut them higher for grass to grow at the same rate as alfalfa; leaving more stem and some leaf area at the bottom of the plant, about 3 to 5 inches, will improve the grass recovery, Welch notes.

He cautions if it’s cut too short, the grass will not recover as effectively after harvest. Cutting alfalfa grass mixtures higher will improve grass recovery but decrease forage yield per acre. Raising the cutter bar to favor grass improvement will decrease forage yields.

The risk of drought and yield loss can have a severe impact on a field planted with an alfalfa and grass mix.

Grasses tend to be less drought-tolerant than alfalfa, so the mixed stand might be completely different at the end of the season in areas that have experienced a drought.

While planting grass and alfalfa requires more complex management practices, there are still simple management options for farmers looking to grow the two together.

Finding a solution for grass and alfalfa
The trick to establishing a successful feeding program with grass and alfalfa is to find a solution that doesn’t compromise alfalfa quality. One suggestion is only planting one crop in a given field.

“With the high cost of inputs today, farmers need to figure out ways to maximize production,” Welch says.

“To get a good crop, we need to make sure we’re managing the species to the fullest, and that would apply to alfalfa, corn or orchardgrass. Managing these forages independently may actually increase a farmer’s production.”

Growing alfalfa and grass separately not only helps farmers simplify their management practices, but it also helps nutritionists when they’re assembling a diet.

“Grass is a great feed,” says LaCount, “but I think it’s much more appropriate to plant grass in one stand and alfalfa in another stand, harvest them at their optimum maturities, store them separately and let nutritionists pick and choose how much of each one they want in the ration rather than rely on some uncontrolled mixture.”

Dairy farmers can then use a total mix ration (TMR) mixer to find the right amount of ingredients than can maximize milk production, Welch says.

“Why are we trying to do the TMR in the field? Why don’t we do the TMR in the TMR mixer?” asks Welch.

Monocultures provide farmers with a simple approach to growing grass and alfalfa, but instead of the complication the mixed stands present, the focus is on the one crop in the field.

To sum it up, there are three key management considerations farmers need to make in order to successfully grow mixed stands. The starting point is to choose the seed variety that is right for the field.

Once the seed has been selected, determining optimal seeding practices helps ensure the growing season gets off to a strong start.

To get the highest nutritional value from stands, farmers need to make sure they are cutting at the right time. If this is done once the plants are too mature, they become more difficult for dairy cattle to digest and add inconsistency to dairy diets.

A proven management practice that makes it easier to seed, grow and cut at the optimal times is to consider planting monocultures that separate alfalfa and forage grass stands and recombine these ingredients for optimal dairy diets.

Grass and alfalfa will always offer nutritional benefits in dairy cow feeding programs, even as diets evolve.

But farmers should always consider what will best maximize dairy cattle production, and what will be best for their operation, before developing their agronomic and nutritional blueprint.  FG

Grass and alfalfa will always offer nutritional benefits in dairy cow feeding programs, even as diets evolve. Photo by FG staff.



Gary Nowaczyk
National Alfalfa and Forage Manager