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All about horse hay

You probably handle hay every day, but how much do you really know about the dried forage you feed your horses? Here are the facts about the foundation of equine diets.

If there’s any common ground in the equestrian world, it’s covered in hay. No matter the breed in the paddocks or the type of saddles in the tack room, every facility that houses horses will have a loft, shed or other space full of hay. Dressage riders, team ropers and trail riders alike toss flakes of hay over fences—and probably end up brushing the excess off their shirts.

Hay is a uniter of horses, too: A humble lesson horse and a racehorse may almost seem like different species until you place a net full of sweet-smelling wisps in front of each. Then they are both simply happy horses.

A horse eating hay out of a haynet.

So which type of hay is best for your situation? That depends on your horse and specifics of batches of hay.

Given the essential role hay plays in our everyday lives, it’s a bit surprising that we horse people don’t know more about it. Yes, we know it’s dried grass, and yes, we understand it’s the foundation of a healthy equine diet. And every seasoned horse keeper is familiar with the hallmarks of good quality hay. But when it comes to the specific plant types, their attributes and exactly how much to feed, we may be less informed than we realize or want to admit.

“Often horse owners understand their horses very well and pay close attention to feet, teeth and health care, but can’t tell you what kind of grass is growing in the pasture,” says equine nutritionist Burton Staniar, PhD, of Pennsylvania State University. “The plants horses are eating are not the horsemen’s main focus, yet forage is the basis of what keeps their horses healthy and happy.”

To fill those gaps in knowledge and help horse keepers everywhere develop an even greater appreciation for all that hay provides, here’s a closer look at the forage that unites us.

Legumes: Packing in the nutrients

The easiest way to start thinking of hay types is to break them into two distinct groups: Legume and grass hays, the latter of which can be further divided into cool-season and warm-season grasses. The varieties of hay available will depend on your area of the country. What’s the difference between these two types of hay?

Let’s start with legumes, which are generally more nutrient-dense than grass hays, with greater calorie content. “Legumes tend to be higher in crude protein, energy and calcium, lower in fiber values, and moderate in nonstructural carbohydrates,” explains Krishona Martinson, PhD, an equine extension specialist at the University of Minnesota. “They are best suited for horses with higher nutritional requirements, including performance horses and lactating mares.” Because legumes tend to be lower in nonstructural carbohydrates compared to cool-season grass hays, the forage can be an option for horses with metabolic syndrome or a history of laminitis. However, these horses also tend to be overweight, which means that alfalfa, with its greater energy density, is best fed as part of the diet versus the entire diet.

The two legume hays most often used as forage for horses are alfalfa
—the most common—and clover. Some other legumes such as birdsfoot trefoil, lespedeza or peas, are fed to cattle but are not generally used for horses.

The high nutrient content of alfalfa that makes it a great choice for some horses means it’s less suitable for others. “Lactating mares can benefit from some alfalfa in the diet,” says Judy Downer, PhD, of the College of Central Florida. “Mature horses don’t need that much protein. Even a thin horse or working horse needs energy calories, not additional protein.”

Legume hays tends to be more expensive than grass hays but feeding them to a horse who doesn’t need the extra nutrients isn’t just a waste of money. “What bothers me about feeding too much alfalfa is that we overdo the protein (wasting protein) and shortchange the horse on fiber,” says Downer. “And if horses consume more protein than they need, they drink more water, and simply break down the protein and excrete it in urine. The stall will smell like ammonia. Air quality in the barn will be unhealthy, increasing risk for lung irritation and respiratory disease, especially in foals. Excess protein in a hardworking horse increases risk for dehydration and overheating.”

The other commonly fed legume hay is clover—usually crimson or red—usually mixed with grass hay. Common white and ladino clover can be baled but are usually grown
for pasture.

There’s also perennial peanut hay—sometimes called Florida alfalfa—which is a different plant than the type that produces the peanuts we snack on. “Perennial peanut is a legume- like clover, but only grows in the South,” says Downer. “Its nutritional properties are similar to alfalfa and it is very leafy and palatable. Peanut hay can be hard to find, however, because most of the people who grow and harvest it tend to keep it for their own horses.”

Warming up to grass hays

Grass hays, the second primary category of hay, tend to be lower in crude protein, energy, calcium and fiber than legume hay, and higher in nonstructural carbohydrates. All of this makes them suitable to feed to a wide variety of horses, particularly those that are idle or are easy keepers.

The category of grass hay can be further broken down into warm-season and cool-season varieties. Of the warm-season grasses, Coastal Bermudagrass is probably the hay most commonly fed to horses in the South, according to Downer.

“[Coastal Bermuda] makes wonderful pasture in the South because it is heat resistant and keeps growing through the hotter months,” she says. “It also grows well in sandy soils—very hardy and well-rooted. It makes a good stand and good forage, as long as you keep it grazed down or mowed—so it’s in a vegetative state of growth and not too mature… It should be cut just as it starts entering the seed stage, and no taller than 12 to 14 inches in height. Since it grows so fast, however, a person can get several cuttings during the summer. It loves a hot, humid environment.”

A variety of Coastal Bermudagrass cultivars have been developed, says Downer. “The University of Georgia came up with a variety called Tifton, which is a little higher in nutrient levels than the average coastal hays,” she says.

A big advantage to warm-season grass hays, including Coastal Bermudagrass, is that they are low in sugars because of the way they store carbohydrates. “If a horse is prone to laminitis and unable to handle sugars, I recommend feeding a warm-season hay,” says Downer.

Nonetheless, a transition from a cool-season hay to a warm-season variety needs to be done carefully. “This should be done very slowly because there are digestibility differences,” says Downer. “The stalk in Coastal Bermudagrass is very fibrous and tends to twist. A horse might not be able to chew it thoroughly, which could result in digestive upsets. It also tends to pull moisture out of the gut because it is so dry, and horses could become dehydrated and impacted. It’s a good feed, but if you shift a horse over to coastal hay too quickly you may end up with risk for colic,” adds Downer, who recommends allowing three weeks for the transition to warm-season coastal hay.

In some regions of the country, you may hear of a warm-season grass hay known as teff. This plant, originally grown in Ethiopia as a grain, is one of the earliest domesticated plants. Teff is generally a low-nonstructural carbohydrate hay and in recent years has become popular forage for horses with insulin resistance and similar issues.

Dawn Sherwood, PhD, an extension specialist with Oregon State University cautions that warm-season grasses aren’t always lower in nonstructural carbohydrates (or sugar). The sugar content will vary depending on the growing conditions, soil fertility and other factors. “If you are looking for low-sugar hay for a metabolic horse, it’s all about how the hay is grown and managed,” she says.

For this reason, Sherwood says, it is important to have the hay tested when buying it for a horse that has a medical need for low nonstructural carbohydrates. “If you are selecting hay for a horse that needs low sugar, always have it tested—whatever kind of hay it is,” she says. “Many hay producers get their hay tested and you can just ask them for the test results.”

The coolest grass hays

In parts of the United States where it doesn’t get quite as hot, cool-season grasses are the main species of grass hay grown. These include ryegrass, bluegrass, brome, timothy, and orchardgrass. These grasses generally do well in cooler weather, to the point they may go dormant during hot weather.

Kentucky bluegrass is used more for pasture than for hay. It is nutritious, palatable and winter hardy but can’t tolerate hot, dry summers. While a good pasture grass, it’s very low-yielding as hay.

Fescue is a cool-season grass that also grows well in relatively warm climates. It is common in the “transitional” zone across the middle of the continent. This is due, in part, to an endophyte fungus that lives in the seed heads (in symbiotic relationship with the plant) that make the plant better able to survive hotter weather and drought. In fact, endophyte-infested varieties, being hardier, tend to take over stands of non-infected fescue.

While this endophyte infection is good for the plant, it can be devastating to horses who graze it. Specifically, fescue toxicosis in broodmares causes prolonged gestation, leading to larger foals that are difficult to deliver, and increases the risk of so-called “red bag” deliveries, in which the placenta detaches from the uterus prematurely, depriving the foal of oxygen. Fescue toxicosis can also inhibit or entirely stop a mare’s milk production. Because of these risks, it is recommended that broodmares be removed from endophyte-infected forage sources several months before foaling.

Other than broodmares, most horses can be safely kept on fescue pastures, says Downer, but frequent mowing is needed to keep plants from maturing and producing seedheads, where the fungus grows. For fescue hay or pasture, you’d ideally plant a variety that doesn’t have the endophyte fungus, but keep in mind that these stands may eventually be invaded and taken over by endophyte-infected fescue because it is hardier.

Matching the hay to the horse

So which type of hay is best for your situation? That depends on your horse and specifics of batches of hay.

First, consider maturity of the hay when it’s cut. Regardless of the type of hay, the nutritional value, including protein and vitamin levels, will vary depending on the timing of harvest—whether the plants were immature and growing or had become tall and more mature. An older, more mature plant contains more lignin (a non-digestible fiber) to support its height and structure, and fewer nutrients. So while many people may think a first, second or third cutting of hay from a particular field is “better,” the cutting doesn’t have as much to do with hay quality as does the maturity of the plant at harvest.

“The first cutting in many regions might have a few more weeds because those grow early in the season,” says Staniar. “Second and subsequent cuttings may be a little ‘cleaner,’ but the most important aspect, if you are evaluating suitability for different animals, is maturity.” A plant that has bloomed or gone to seed has fewer nutrients and more fiber. When you open a bale of such hay, stems will be stiff rather than soft, and there will be more stems than leaves, with mature seedheads.

But this doesn’t mean that hay harvested earlier is “better” than hay harvested later. In fact, each type might be ideal for certain horses. “You’d want a relatively immature hay (with a lot of leaves and less stems) for young, growing horses, lactating mares, hard-working athletic horses and any other horses that need a high-quality hay with high nutrient levels,” says Staniar. “The immature plant will be highly palatable and very digestible.”

On the flip side, more mature hay is a good option for the easy-keeping horse that isn’t working hard. “That hay will have more fiber---more stem and less leaf---and be less digestible. Often it’s less expensive, too. This doesn’t mean it’s a bad hay. If it’s been made well, not dusty or moldy, it can be a very good hay for the right horse,” says Staniar. “It provides the necessary fiber and gives the horse something to chew on for more of the day.”

Downer agrees that hay with lower nutritional value can be helpful in managing horses for health and happiness. “If you feed an overweight horse only one flake of rich alfalfa, it would meet the horse’s nutrient needs but would be eaten quickly and the horse would still be hungry---standing around eating nothing,” she says. This could lead to ulcers or boredom that could predispose a horse to wood chewing or stereotypies.

Of course, palatability is also important and will affect how much hay a horse is likely to eat. More mature and fibrous hay isn’t appealing to some horses taste-wise. It also stays in the gastrointestinal tract longer, making the horse feel full and likely to eat less. Hay made of shorter, less-mature plants is generally more palatable and digestible, plus it moves through the digestive tract faster so the horse can eat more to get more calories and nutrients.

With all the types of hay available and the variety of ways it can be harvested, there are many options to choose from—in theory, at least—when it comes to feeding your horse. However your choices are likely limited by what grows locally, since it’s expensive to haul hay; in fact, the price of shipping can surpass the price of the hay itself.

Nonetheless, sometimes shipping hay is unavoidable. Not every region of the country has ideal conditions for producing high-quality hay. During rainy periods, it is difficult to dry hay enough to bale. Hay baled at moisture levels greater than 16 percent can become moldy, making it unsuitable for horses. In arid regions, farmers can simply turn off irrigation systems when it’s time to cut, rake and bale hay. In humid regions, however, hay may have to keep growing several weeks beyond optimum maturity until weather is dry enough for harvest.

Some farmers use preservatives, typically organic acids that are not harmful to horses, to inhibit mold in hay baled in less-than-optimal conditions. The main one used is propionic acid, which is also produced naturally by bacteria in the horse’s digestive system. These preservatives don’t change the texture of the hay, but may affect the smell and even taste, leading horses to eat less of it until they get used to it.

In very wet areas, many horse owners have alfalfa shipped in from more arid regions, simply because that hay is higher quality than what can be grown locally. Growers who cater to the horse market are good at putting up high-quality hay, but you’ll pay a premium price for it.

All of these factors can affect your choice of hay for your horse. “Here in Florida we often have to pay a lot for hay because at least half the cost is for shipping. I have found that even though it is more expensive, it is more important to select a hay that the horse is able to eat—consuming all the hay that you buy. Otherwise, you are really wasting your money,” says Downer.

Although we may refer to them by the single, simple term “hay,” these cultivated,
dried forages are as varied as the horses who happily dine on them. Understanding this opens a world of hay options you may not have known existed and provides the opportunity to select the very best type for your horse. 

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