Making Hay

Learn what goes into growing and harvesting quality hay so you can recognize and select it for your horses.

The difference between good hay and poor hay is often in the harvesting. Poor timing of harvest processes or bad harvesting conditions can render a good hay crop poor or unsafe for horses, as it might contain mold or dust. Hay must be baled at the proper stage of drying--if it is cured too long it can lose nutrients or be dusty, but it shouldn't have so much moisture that it molds. Other factors that affect hay's nutritional value include stage of maturity when cut, and whether it's the first or a later cutting (after regrowth).

Stage of Maturity

Glenn Shewmaker, MS, PhD, a forage specialist and extension assistant professor at the University of Idaho, says hay producers should try to look at the field at least a week prior to when they think it might be ready to cut. "This is the best time to control the quality in terms of plant maturity," he says. If it's alfalfa, you can see whether it's already blooming, which makes it more attractive to blister beetles--some species are deadly to horses if they are present during harvest and their bodies end up in the hay.

When buying hay, talk with the producer and agree on the stage of maturity at which it should be cut. Plants cut in early- to mid-maturity have higher levels of protein and other nutrients and would be a good choice for lactating mares or young growing horses. Mature hay would be more ideal for an adult, idle horse. Sometimes hay is cut later than planned because harvest is delayed by rain. Some hay producers let hay grow longer, since mature hay produces more tonnage per acre than immature hay.

"Hay prediction sticks measure stem length of the growing plant and have a scale (for bud and open flower stages) to give an index for estimating acid detergent fiber, neutral detergent fiber, and relative feed value, but most horsemen and hay producers just look at relative maturity," says Shewmaker. "If it's alfalfa, you look for buds or flowers. If it's grass, you look for boot stage (when the seed head has not emerged, but it has begun to swell the top of the plant) or seed heads to indicate maturity. With mixed hay (grass and alfalfa), one species is generally ahead of the other in maturity, so timing of cutting must be a compromise."

Differences in Cutting

The first cutting often grows slower in the cool spring weather. Later cuttings grow faster in the heat of summer. "First cutting, whether alfalfa, grass, or mixed, is often a nice all-purpose hay," says Shewmaker.

First cutting hay usually has good yield, plenty of fiber, and adequate energy and protein. Although it might have a coarse stem (if it's alfalfa), most animals like it, and it's good feed because it grew slowly enough to accumulate nutrients.

"Hot-season cuttings are often very clean (fewer weeds, since they did not regrow), leafy, and fine-stemmed," continues Shewmaker. "But generally the animals don't like it as well because it grew too fast. There's not a high concentration of sugars, for instance. But for a laminitic horse or any horse that's sensitive to sugars and needs to be on a diet with less nonstructural carbohydrates, the hot-season cuttings are generally safer for that animal.

Other extension specialists have noted that many horses eat second-cut, fine-stemmed alfalfa hay in preference to first-cut hay, which is stemmy and less palatable.

"The end-season cutting is richer in nutrients again because of slower growth when nights are cool," he continues. "Even if it's blooming, it still may be very nutrient-dense. That cutting seems to still maintain its quality after bloom stage."

Time of Day Makes a Difference

Hay cut in the late afternoon has higher nutrient content than hay cut in the morning. Plants accumulate sugars and starches during the day (through photosynthesis), then they use up nutrients at night as they grow, explains Shewmaker. For highest nutrient values, select hay cut in the late afternoon. "But a horse that is prone to insulin resistance problems or laminitis would do best with hay cut in early morning, when plants are lowest in sugars and starches," he says.

Moisture Considerations

Time of day the hay is baled also makes a difference--the hay can be too moist (with risk for mold formation) or too dry, which leads to shattering and loss of leaves when going through the baler. In a dry climate hay producers try to bale hay with a little dew on it to minimize leaf loss, since most of the nutrients are in the leaves rather than the stems. In a humid climate it might be impossible for hay to dry out underneath (because of ground moisture) without the harvester turning it.

There's tremendous variation in what's ideal for hay moisture at baling, according to Michael Thomas, who does custom hay harvesting on ranches near Salmon, Idaho. "A certain figure might be too dry in some situations and too wet in others," he says. "It depends on whether it's alfalfa or grass (and the type of grass), maturity of the hay when cut, whether the bales will be small or large, whether baling takes place soon after cutting or several days later, weather conditions, air moisture, ground moisture, etc.

"In some situations, 8 to 15% moisture (the traditional rule of thumb used as a guideline for when to bale) is too dry; leaf quality will be lost," he explains. "Leaves shatter during baling and much of that material won't end up in the bales--especially small bales. You'll end up with 'stemmy' hay, few leaves, and lots of dust."

There's a difference between mold dust (mold spores that become airborne when you break open a bale) and naturally occurring dust, such as plant particles, pollen, or soil dust. Hay baled too dry will always be dusty, due to tiny particles from leaf shattering. Road dust often drifts over nearby hay fields and plants will be dusty even before the hay is cut.

"To ensure the hay won't be too dusty for horses, it often must be baled with some moisture on it, to settle the dust and bind it to the hay," explains Thomas. "This keeps the leaves together instead of shattering and gives the hay a softer, more palatable texture.

Many extension agents and forage specialists say to avoid baling hay with a moisture content of more than 16.5% because it has the potential to mold, especially if the bale is tight. Thomas says he feels that in very dry conditions or on dry ground, the best-quality small grass bales might need to be baled at even higher moisture levels. Thomas says, "At the other extreme, if you're making big bales, with some types of hay you'd have to be very careful baling anything over 15% moisture because the bales are so dense. The mass per square inch is so much greater, and there's less surface area for continued drying."

Stem moisture is the key factor. "In arid regions it's best to bale after sundown when hay is not quite so dry," says Shewmaker. "Usually in the early morning, if there's a lot of dew, the hay will be too wet to bale. You may have only half an hour of ideal baling conditions in early morning before hay becomes too wet."

Sometimes hay is baled too soon, before it's adequately dry (especially if the producer is trying to get it baled before a predicted rainstorm). If it gets rained on after it's cut, it takes longer to dry out enough to bale. The extra drying time and "bleaching" reduces nutrient quality, and the hay also becomes dusty due to more shattering of the dried leaves when baled.

Once hay is in a compact bale, a little rain won't hurt it as much as if it's still in the windrow. This is why producers generally try to bale hay before a storm, even if there isn't time to get the bales hauled. Moisture won't penetrate the bales very much unless it's a downpour or an all-day rain.

"This is the tricky part," says Shewmaker. "Hay needs to get dry before baling, then hopefully baled in the evening when humidity rises a little, so leaves stay attached. This is especially important for alfalfa, since those leaves shatter worst when dry. For small bales, I prefer moisture content to be below 16% for horses, since you usually won't get any mold in these conditions."

Some producers use moisture meters to check hay and determine when to bale a field, although some have an intuitive sense about moisture levels just by feeling and scratching the cuticle on the stems, or using various twisting and snap tests to check stem dryness.

Thomas says one way to check stem moisture is to reach under the windrow for a small sample of hay near the ground. "Grab a small swatch about an inch in diameter that you can easily hold between your two hands to twist (one hand going one way and the other hand the opposite direction, see image) back and forth. If the hay stems do not break after a few twists/turns, it's not dry enough," says Thomas.

Experience is the best teacher for getting a "feel" for how dry the stems should be.

Take-Home Message

There is and art and a science that goes into growing and harvesting hay, no matter the type of bales being produced or the animal the hay is intended to feed. All hays are not the same, and even hay from the same field can end up varying in quality depending on the time of day cut and baled. Work with a reputable hay producer or dealer to get the best-quality hay that suits your horses' needs.

About the Author

Heather Smith Thomas

Heather Smith Thomas ranches with her husband near Salmon, Idaho, raising cattle and a few horses. She has a B.A. in English and history from University of Puget Sound (1966). She has raised and trained horses for 50 years, and has been writing freelance articles and books nearly that long, publishing 20 books and more than 9,000 articles for horse and livestock publications. Some of her books include Understanding Equine Hoof Care, The Horse Conformation Handbook, Care and Management of Horses, Storey's Guide to Raising Horses and Storey's Guide to Training Horses. Besides having her own blog,, she writes a biweekly blog at that comes out on Tuesdays.

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