Stage of Maturity
Glenn Shewmaker, State Forage Specialist, University of Idaho, says that whether you are producing hay or buying it, try to look at the field at least a week prior to when you think it might be ready to cut. “This is the best time to control the quality in terms of plant maturity, and to see what’s actually in the field—such as certain weed problems,” he says. If it’s alfalfa, you can see whether it’s already blooming. You can also see if there are patches of undesirable plants such as cheat grass, foxtail or noxious weeds.

If you are buying hay, talk with the producer and agree on the stage of maturity at which it should be cut. For some classes of livestock you may be happy with mature hay, with more tons to the acre, even though it will contain more fiber and less total nutrients per pound of hay. For young, growing calves, or lactating cows, you may want the hay cut at an earlier stage of growth, for higher nutrient content (especially protein). “The mistake many people make is trying to make one type of hay fit all, but it’s best to target the final product to different classes of stock,” says Shewmaker.

The highest quality hay (in terms of protein and other nutrients) is needed for lactating dairy cows and this type of hay would be too rich for most beef cattle. Newly weaned calves would require the next highest class of hay, then beef cows with calves. The lowest quality hay (that might be weather damaged and contain dust and mold) can generally only be utilized by non-lactating beef cattle (dry cows or mature bulls that are not going to be used for breeding any time soon). There are also quantity issues; you may choose to let some hay get more mature than what you’d want for dairy cows or growing calves, just because mature hay (growing longer) produces more tonnage than immature hay.

Stockmen need to understand the hay making process and the differences in plant maturity at harvest—and what that means in terms of nutrient content. If you want hay with high nutrient level, plants cut in early to mid-maturity tend to have more protein and would be a good choice to feed lactating or young growing animals. Sometimes hay is cut late, however, if harvest is delayed by rain, and ends up being more mature than planned.

“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 stockmen and hay producers just look at relative maturity,” says Shewmaker. “If it’s alfalfa you look for buds and then for flowers. If it’s grass you look for boot stage (if you want a high nutrient level) or seed heads to indicate more maturity. One of the problems with mixed hay (grass and alfalfa) is that one species is generally ahead of the other in maturity, so the timing of cutting must be a compromise in this instance,” he says.

“Our use of the detergent fiber test (which is important to the dairy industry) has often led us to discount grass hay too much. There are higher fiber levels in grass hay, but it is a more digestible fiber. Some of the newer tests, like the digestible NDF (neutral detergent fiber) and relative forage quality, as opposed to the older tests for relative feed value are better measures, and more accurately compare grass and mixed hays with alfalfa,” says Shewmaker.

Differences in Various Cuttings
There are differences between cuttings, due to the season and how fast the hay is growing. These differences will vary somewhat from region to region, depending on how early in the spring the hay starts to grow, and how long the growing season is (how many cuttings you can get) during the season.

The first cutting often grows a little slower in the cool weather of spring than second and third cuttings that grow faster in the heat of summer. A late fall cutting may grow more slowly. Slow growing hay will generally have more nutrients—especially minerals--per pound than fast-growing hay (that didn’t have as much time to take up nutrients from the soil). “First cutting, whether alfalfa, grass or mixed, is often a nice all-purpose hay,” says Shewmaker. It has good yield, plenty of fiber, and adequate energy and protein. Even though it might have a coarse stem (if it’s alfalfa) all animals like it and it’s good feed because it grew slowly enough to accumulate the needed nutrients.

“Hot season cuttings, which include second, third, and in some regions a fourth, are often very clean (fewer weeds, since they did not regrow), leafy and fine-stemmed. 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,” he explains.

The end-season cuttings are richer in nutrients again, in the fall when nights are cool. “The final cutting or cuttings will have high energy levels because of slower growth. Even if it’s blooming, it still may be very nutrient dense. That cutting seems to still maintain its quality after bloom stage,” he says.

The time of day you cut the hay also makes a difference in quality. Hay cut in the late afternoon has higher nutrient content than hay cut in the morning. The plants accumulate sugars and starches during the day (through photosynthesis) and then use up these nutrients at night as they grow, explains Shewmaker. Thus for highest nutrient values, cut hay in late afternoon.

Moisture Considerations
Time of day the hay is baled will also make a difference in quality, regarding moisture levels—whether the hay is too moist (with risk for mold formation) or too dry, which leads to more shattering and loss of leaves when going through the baler. In a dry climate, most hay producers try to bale the hay with a little dew on it, to minimize leaf loss, since most of the nutrients of alfalfa or grass plants are in the leaves rather than the stems. In a humid climate the hay may be impossible to get dry underneath (drawing ground moisture) without turning it.

There’s a lot of variation in what’s ideal for hay moisture at baling, according to Michael Thomas, a rancher near Salmon, Idaho who has done custom hay harvesting for 18 years. “A certain number figure might be too dry in some situations and too wet in others. It depends in part 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 the cutting or several days late, weather conditions, air moisture, ground moisture, etc.” he says.

“In some situations 8 to 15 percent moisture (the traditional rule of thumb used as a guideline for when to bale) is too dry; the leaf quality will be lost. Leaves will shatter during baling and much of that material won’t end up in the bales—especially if it’s small bales. You’ll end up with stemmy hay and very few leaves, and lots of dust,” says Thomas.

There is a difference between mold dust (mold spores that become airborne when you break open a bale) due to hay being too wet when baled and the naturally occurring types of dust such as pollen or rock dust. Hay baled too dry will always be dusty, due to tiny plant particles from leaf shattering. Road dust often drifts over nearby hayfields and the plants will be dusty even before the hay is cut. “To ensure the hay won’t be dusty, in many situations it must be baled with a little moisture on it, to settle the dust and bind it to the hay. This keeps the leaves together instead of shattering and gives the hay a softer, more palatable texture,” explains Thomas.

“In dry conditions or on dry ground, the best quality small bales might need to be baled at 24 to 30 percent moisture on grass hay. 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 percent moisture because the bales are so dense. The mass per square inch is so much greater in big bales and there’s less surface area for continued drying,” explains Thomas.

Stem moisture is the key factor. “In arid regions it works well to bale after sundown when hay is not quite so dry,” says Shewmaker. Many people try to bale hay at night when moisture conditions are more favorable than during the heat of the day. “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 the early morning before the hay becomes too “tough” (wet with dew),” he says.

Sometimes it’s hard to make ideal hay, since timing for baling must also take weather into consideration. Hay is sometimes baled too soon, before it is adequately dry (especially if the hay producer is trying to get it baled before a predicted rainstorm, for instance). Hay that was dry and nearly ready to bale will lose a lot of its quality if it gets wet and has to dry out again. 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 its nutrient quality, and it may also become dusty due to more shattering of the dried leaves when baled.

Once it’s in a compact bale, a little rain won’t hurt it as much as if it’s still in the windrow, and this is why the producer generally tries to get it baled before a storm, even if there isn’t time to get the bales hauled. Moisture won’t penetrate the bales much more than an inch or 2 unless it’s a downpour or an all day rain.

“This is the tricky part,” says Shewmaker. “The hay needs to get dry before baling, then hopefully baled in the evening or during the night when the humidity raises a little, so the leaves will stay attached. This is especially important for alfalfa, since those leaves tend to shatter worst when dry. The dryness factor is a little less important for grass. For small bales, I prefer the moisture content to be below 16 percent, since you usually won’t get any mold in these conditions. If it gets above 18 percent, mold becomes a high probability,” he explains. Some producers use moisture meters to check the hay and determine when to bale a field, though some who’ve been putting up hay a long time have an intuitive sense about moisture levels just by feeling the stems.

“Most moisture meters are designed for bales (compressed forage) and don’t work very well in a windrow. My colleague Ron Thaemert developed a compaction tool made from PVC pipe, that compresses a forage sample from a windrow,” says Shewmaker. “You can use this probe to measure the moisture in windrowed hay, before you even pull the baler into the field. You can also use the traditional physical tests and go by feel and by scratching the cuticle on the stems, or various twisting and snap tests to check stem dryness. We advise using both the old and new technology,” he says.

Thomas says that one way to check stem moisture is to reach under the windrow to grab a small sample of hay near the ground. “Grab a small swatch an inch or two 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) back and forth. If the hay stems do not break after a few twists/turns, it is not dry enough,” says Thomas. Experience is the best teacher for getting a “feel” for how dry the stems should be.

Big bales must be baled with even more ideal conditions than small bales, to avoid mold, spoilage and loss of quality. “The bigger the bale, the more potential problem with moisture. Big bales must be 2 to 3 percent drier than a small bale when baled. They are usually more dense and can’t dissipate moisture like a small bale that has more surface area for the volume.” There is some air movement around all edges of a small bale and it can continue drying a little more until it is stacked. But in a large bale the excess moisture cannot escape.

SIDEBAR: Haying Equipment
Most cutting machines today crimp and condition the hay as it’s cut, so it will dry faster and be ready to bale a day or two sooner than with older methods. This reduces the risk of getting it rained on while waiting for it to dry, and also improves the quality, since less nutrients are lost. Prolonged heat and drying destroys some of the protein and vitamin A. “The longer the hay sits there, drying, the less nutrients and more fiber you end up with,” says Shewmaker.

Sometimes you can’t avoid rain; the hay must be cut before it gets overly mature and you have to take your chances. Rain is less damaging if it hits soon after cutting, and most damaging if the hay was nearly dry when it gets wet again. “There are tedders that fluff the hay up and help it dry faster, and windrow inverters that are better than raking,” says Shewmaker. “These pick up the hay and usually have a belt that carries and turns it upside down; it’s more of a lifting action. With a rake, if the hay is too wet, it just twists into a rope. With the inverter the hay is more fluffy; if the top is dry you can turn it clear over and the hay dries more thoroughly,” he says.

“Many producers are now using disc or rotary mowers rather than reel-type cutters. There might be slightly more dirt in the hay, however, since a rotary mower can cut closer and may run into mole hills, ditch banks, uneven ground. Rotary mowers work better on grass, however, than a sickle mower,” he explains.

“It’s important to dry the hay as quickly as possible, so it helps to rake it (turn it over). A common strategy is to spread the windrow out as wide as possible, for fast drying,” says Shewmaker. Then it can be turned with a rake a day or 2 later, making the windrow the proper width for the baler and ensuring that the hay next to the ground is then uppermost for further drying. A person can often turn the hay just 30 minutes or so ahead of baling, just to make sure the portion that was on the ground gets dry.

“Stem moisture is the issue. The leaves on top dry quickly. So it helps to rake and turn it, at the proper moisture level (like a day or 2 after cutting), which is sooner than most people do, when moisture is about 40 percent.” Even turning it just a short while before baling can often allow you to bale it a day earlier than you could otherwise.

The baler used can make a difference, also. Some of the older balers did not compact the hay as much and there might be more moisture dissipation (and less spoilage from mold), but on the flip side the looser bale has more quality loss during storage. A denser bale not only contains more hay but has less loss due to weather damage since moisture doesn’t penetrate as far into it (from rain, or from damp ground, on the bottom). There is always a certain percentage of loss around the outside of a bale, and the bigger and denser the bale, the less loss there will be.

There’s also less total hay lost in the field, when using big bales. “You gather up more of the hay in the windrow. With little bales, there’s always a little more leaf loss; too many of the leaves fall out of it. The larger the baler, the more material is kept in it,” he says. The big round balers that roll the hay around and around instead of chopping it into “flakes” have the least loss of leaves and quality. All the stems and leaves are intact.

Windrow size/width is also important, and should be coordinated with the size of the baler. You want to pick up as much hay as you can in each trip around the field (to save time and fuel) but also not have the windrows so big that the baler misses some of the hay along the edges of the windrows.

“Storage considerations are also of utmost importance. It just makes sense to protect the hay (for less spoilage) by keeping it up off the ground or stacked on a crushed rock base for good drainage, and well covered—either in a barn or with a good tarp,” says Shewmaker.

SIDEBAR: Hot Hay
If hay is baled too “green” or wet there will be some mold and spoilage, and risk for excessive heating. This is often a greater problem in big bales than small square bales, since the mass per square inch is greater in big bales and there is less surface area for continued drying. Incidence of hay fires has increased during the past 2 decades, with the greater use of large bales. The tighter the bale (the more hay packed into it, with no air spaces), the more risk for heating. If wet small bales are hauled and stacked before they have a chance to dry more (especially if tightly packed inside a barn) they may be just as likely to catch fire as the bigger bales.

Hay that heats too much, even if it didn’t get hot enough for spontaneous combustion and has cooled, will generally mold or be discolored and stuck together. The stuck-together hay may be “caramelized” (the heat has broken down some of the starches into sugars and the hay is brown and sweet-smelling) or “tobaccoed” (brown and musty from heat damage). Even though cattle like the sweet taste of caramelized hay, it has less nutrient value because much of the protein has been destroyed.

If hay is too moist when baled, it may heat so much that it eventually ignites, due to a chemical fermentation process. Baling hay with more than 30 to 40 percent moisture content will almost always result in spontaneous combustion. A large, tight bale seals the wet material into an airtight package that hastens the combustion process. Sometimes it may take only a few days for hot hay to burst into flames, or may take as long as 6 weeks to generate enough heat to catch fire or turn black.

The type of hay, the amount and type of bacteria present—which aid the fermentation process—along with the various molds and weather conditions all play a role in determining how long it takes the damp hay to catch fire. Always check bales for heat before hauling and stacking them, if there’s any chance they may be still damp from rain (if moisture penetrated more than a couple inches) or were baled a little too green.

Heat is generated when certain microbes multiply and “digest” nutrients in the fermentation process that occurs with moist hay. High quality hay, especially alfalfa, may be more prone to heat enough to burn because it contains more nutrients for the microbes to feed on. If the heat is not dissipated rapidly enough to keep the temperature below 150 degrees, there is danger of spontaneous combustion.

If you suspect the hay may be heating, open a bale to check, or put a thermometer into a big bale. You can insert a thermometer into a short metal pipe and poke it into the bale. If temperature is higher than 140 degrees, check the hay again—every few hours—to see if it is coming down or going up. If it gets up to 180 degrees, combustion is about to begin or has already begun.

If stacks of big square bales are too high and wide, there is less chance for heat to dissipate and they may start smoldering. The hay may simply turn dark brown or black, or may burst into flames if the stack is opened, giving the hot hay access to oxygen. Recommendations for stacks of big square bales is that they be only 4 bales high and 2 bales wide, covered with a roof or tarps, and stacked on well drained ground or some type of pad so bottom bales can’t draw moisture.

Close attention should be paid to stem moisture at baling, using equipment that puts a reasonable crimp in the hay so it can dry quickly and evenly. “Green” hay is more likely to heat than are dried-down stems that get too wet from dew or rain. Individual bales that may have absorbed excess moisture from a leaking mainline or the end gun on a neighboring field’s center pivot should be marked and stored separately, well away from a large stack. All it takes is one wet bale to heat and burn down the whole stack.