A Cut Above the Rest: How Cutting Length and Harvesting Impact Feed Quality

Forage quality doesn’t increase after harvest, so what methods can be put into place to ensure haylage yields are of optimum use to animals? Agriculture experts have spent years researching what steps affect forage nutrition and some of the most minute details can alter the makeup of your product.

“We should remember the hay is the highest quality the day that we cut it,” said Dr. Dan Undersander, forage agronomist at the University of Wisconsin-Madison. “We’re simply trying to preserve that quality through the harvesting process. The higher the quality the more animal performance we’ll get in terms of weight gain or milk production.”

Vermeer TM1210 Cutting grass

In his years of experience, Undersander said the cutting height of your forage should be the first step in your management system.

The cutting height is really important, and from the perspective of quality, getting that cutter bar off the ground by 3 or 4 inches – whatever it may be depending on the grass – is pretty important. When you’re going to select a mower conditioner, you need to ask these questions: How high can this thing cut? How high can I get the cutter bar off the ground? In doing that also ask is there a way to get it off the ground without tilting the head back? Vermeer has found that having the head tilted forward on the mower conditioner will result in a cleaner cut, though many manufacturers’ machinery requires you to tilt the head back.

Undersander recommends cutting legume crops at 3 inches, cool season grass at 4 inches and land grass or millet up to 6 inches.

“The reason being, is the grass stores energy in the base of the stem and if we cut too short then it won’t regrow as fast and it won’t yield as much for the year,” Undersander explained. “Alfalfa, on the other hand, and clover store their energy in the root and you can cut them shorter because they will regrow from those carbohydrates in the roots.”

The reason Undersander recommends 3 inches for alfalfa is two-fold. While cutting lower results in more tonnage – it’s all stem and low-quality forage. The second reason is that the lower the cut, the more soil that can be picked up (particularly with disc mowers) when the soil is dry.

“We have seen samples that come through the forage testing lab that oftentimes run as much as 15 to 18 percent ash,” Undersander said. “Inside the grass or alfalfa, we have something close to around six percent ash. So that means these people have picked up 10 percent dirt. What we do know is that beef cattle don’t gain weight eating dirt and cows don’t milk eating dirt.”

I know when I was a kid, we used to basically scalp the ground when mowing. When I look at it now, from the perspective of quality, getting that cutter bar up off the ground is essential.

Vermeer MC4500 Mower Conditioner Cutting Hay

Undersander says keeping the total ash content of forage below 10 percent is a doable goal that’s essential to nutrition. With this 10 percent goal, he’s allotting for an estimated six to eight percent of ash inside the plant and one or two percent dirt.

“We can’t get away from dirt but we can try to keep it to a minimum,” Undersander said. “What we do find is that the more dirt that you have in that sample – remember that each one percent of ash reduces the TDN (total digestible nutrients) content by one percent, because each one percent ash is one percent less nutrients and one percent less minerals.”

According to Undersander, it’s important to remember that the levels of starch and sugar in the forage are 100 percent digestible at harvest. No matter what type of forage you’re growing, the first 15 percent of moisture should be dried off as quickly as possible in order to keep these levels of starch and sugar high for the animals. The faster the dry down the faster you shut down the respiration and the more starches and sugars can be preserved.

“The way to get hay to dry as quickly as possible is first to properly condition the hay and then to make a wide swath,” Undersander explained. “When we are conditioning the hay we can use either a flail conditioner for grassy crops or a roller conditioner for legume crops. We use the roller conditioner for legumes because we have less leaf loss and we want to maintain that quality of the leaves and keep it in the final product that we bale.”

With either type of conditioner, it’s important to properly adjust the head to help ensure adequate conditioning occurs and adjust into a wide swath covering 70 to 80 percent of the cut area. Going to a wide swath conditioner just makes more sense, because you can expose more of the crop to the sun. Why not just let Mother Nature do her work to dry out the hay?

Creating baleage is an additional option that can provide quality hay with less dry down time.

“If we’re making hay we need three to five days for the drying process to get good quality hay made, but if we’re making baleage we can get in there and put it up in one or two days and have even higher quality forage than if we’d put that dry hay up because we’ll have the reduced leaf loss,” Undersander explained. “So baleage can be advantageous in terms of letting us harvest in a time when quality is high but maybe rain is on the horizon and then you still end up with higher quality forage for the animals that we’re trying to feed.”


Cutting Height

  • Legumes – 3 inches
  • Cool season grasses – 4 inches
  • Land grass or millet – 6 inches

Ash Content

Keep total ash content at 10 percent or below which allows for:

  • Six to eight percent of ash inside the plant
  • One to two percent dirt

More Tips and Tricks

  • 15 percent of moisture should be dried off as quickly as possible to preserve starches and sugars
  • Adjust for a wide swath (covering 70 to 80 percent of the cut area) when mowing for a faster dry down
  • Use a flail mower conditioner for grassy crops
  • Use a roller mower conditioner for legumes
  • Adjust mower head to tilt forward (not backward) for the cleanest cut

Questions to Ask Your Hay Equipment Dealer

  • When purchasing a mower conditioner ask:
  • How high can it cut?
  • How high does the cutter bar come off the ground?
  • Is there a way to get the cutter bar off the ground without tilting the head back?