Adapted from an article by Karen Lee/ Kuhn North America
The "hay-in-a-day" harvesting concept, initially proven on New York farms by Cornell Extension's Tom Kilcer is catching on across the country. While touted for quickly producing haylage with maximum nutrient quality, it's also finding dry hay advocates.
Hay that's cut in a wide swath field dries more quickly and evenly, has less chance to get rained on, and has higher total digestible nutrients than conventionally windrowed hay. And, recent University of Wisconsin research suggests a wide swath is more important to dry-down than conditioning – for haylage.
If mowing speed can be accelerated without a conditioner, machine efficiency also improves. And it'll lower the power requirement by about 50%, says Chris Horton, senior product manager for Kuhn North America. "When using a 10-foot mower, this equates to a fuel savings of three and a half gallons of diesel an hour."
So what's a wide swath? Dan Undersander, University of Wisconsin forage specialist, says that the cut forage should cover about 70% of the cut area.
3-phase forage drying
In the first phase of forage dry-down, initial moisture losses occurs through leaf stomata, explains Undersander. These leaf surface openings allow moisture loss to the air down to about 60% hay moisture.
For that first 10 to 15% moisture loss to occur rapidly, the stomata must remain open during daylight. In wide swaths, the forage exposed to sunlight is maximized.
Plant respiration is highest after the plant is first cut, than gradually declines until moisture content falls below 60%. That rapid dry-down reduces the loss of starches and sugars, and preserves more total digestible nutrients in the harvested forage.
Initial moisture loss isn't affected by conditioning, he notes. But once the stomata close, dry-down shifts to the second phase – from the leaf surfaces and plant stems. This is where conditioning begins to increase the drying rate.
The third phase of drying is the loss of more tightly-held water, mostly in stems. Conditioning, which breaks the stems, is critical to enhance drying during this phase.
In one Undersander study, alfalfa was sampled after two months in ensiled tubes. Wide-swath alfalfa had 2.3% less neutral detergent fiber and 1.8% more nonfiber carbohydrates. The difference was due to respiration where starch is changed to carbon dioxide and lost to the air.
In another study, wide-swath haylage had about 1% more TDN, plus more lactic and acetic acid. The higher acid content suggests less rapid spoilage on feed out. He projects that the overall improved forage quality would yield 300 pounds more milk per acre.
Hay versus haylage
"Dry hay also benefits from being placed into wide swaths," reports Horton. "Otherwise the top of a narrow windrow will be overexposed while waiting for the hay on the bottom to dry.
Yet, you still need to condition the dry hay crop to continue the drying process to the point where you can bale, he adds. The drying rate for haylage, on the other hand,
needs to slow down so the moisture level doesn't drop too far.
Some producers are reluctant to try 'hay-in-a-day', says Horton. They don't want to drive on the hay.
Give it a try, he urges. Harvest some hay the traditional way and the 'hay-in-a-day' way. Then test samples to determine which yields higher TDN. "I think (you) will find that it's worth it to do 'hay-in-a-day' because of the increased feed value."