Buying Better Hay -- Stacks of Decisions

Horses eat hay. But why? How does it work? What happens to the hay after it passes the horse's teeth? Knowing how hay functions in the horse's body will help you make better hay choices in the future.

Robert Van Saun, DVM, PhD, an extension veterinarian and associate professor at the University of Pennsylvania, begins his forage feeding lectures with an anatomy lesson. Hay is picked up by the lips and conveyed by the tongue to the molars in the back of the mouth, which are behind where the bit lays. These molars grind the hay into small pieces and mix it with saliva to form a wad of the proper size to move down the esophagus into the stomach. Therefore, good teeth are a requirement for eating hay. That is why adjustments need to be made for older horses with dental problems to get the fiber they need, but might not have the tools to process. This is also why attention needs to be paid to correct dental care throughout the horse's life. Finally, grinding away at hay meets the horse's psychological need to chew. The desire to chew will lead to eating undesirable objects if forage is not available.

The hay chewing in the mouth has provided enough saliva to lubricate the way. Inadequate chewing can lead to inadequate salivation and a lack of moisture in the stomach, which in turn can lead to impaction and gas.

Hay goes through the stomach and the small intestine mostly undigested. The large intestine, all 50-60 feet of it, absorbs water and digests the hay. Horses process hay through fermentation, which is why they're classified as "hindgut fermenters." This is also one reason why so much can go wrong with a horse's diet so quickly.

Horses cannot digest hay by themselves; they lack fiber-digesting enzymes such as cellulase and hemicellulase--enzymes that break down plant wall material such as cellulose and hemicellulose. Instead, horses rely on billions of bacteria and protozoa in the hindgut to provide the enzymes to digest all fiber.

The short-chain end-products of fiber fermentation by bacteria, called volatile fatty acids (VFA), are produced and absorbed with water. VFA digestion can meet up to two-thirds or more of a horse's energy requirements, depending on his needs. In mature, idle horses, hay may provide all the energy required. Also, in the process of digesting hay, the bacteria of the large intestine produce a variety of B vitamins.

All hay contains indigestible parts--hemicellulose, cellulose, and lignin. The amount that is indigestible depends on the adaptation of the microbial population in the horse's gut. In contrast, sugars and starches are 95% digestible. The indigestible parts of hay pass through the horse to be deposited as manure. Although it contributes no nutrients, this indigestible fiber helps carry nutrients to, and waste products away from, the horse's digestive system, keeping him regular. This is similar to how eating oatmeal helps human digestion.

The quality of hay is important to maintaining proper digestion. Quality hay contains nothing harmful (dust, mold, weeds, or foreign objects), provides the necessary nutrients for the horse consuming it, and is palatable. Poor-quality hay usually won't provide enough nutrients, but it again depends on the horse. If the difference in nutrition is made up with grain, the horse might end up digesting too much starch from the cereals. This starch moves into the hindgut and is fermented along with the fiber, causing a drop in pH and an increase in lactic acid, which kills the beneficial bacteria. The dead bacteria release toxins that can cause trouble in the digestive system (such as colic) or problems throughout the body where the toxins are spread by the blood supply (such as laminitis). This is also the major reason feed changes need to be made gradually; time allows the intestinal flora to adjust.

In addition, high-fiber hay might lead to a fiber build-up that plugs the digestive system if sufficient time is not allowed for buildup of the micro-organisms necessary to deal with the change in fiber levels. On the other hand, hay that contains too many nutrients for the horse's work or condition might cause owners to feed less, leading to too little fiber, an empty feeling in the horse's tummy, and a desire to fill it with bits of his stall or bedding.

Therefore, even more than humans, horses need fiber. Unlike humans, horse's delicately balanced digestive systems cannot pass off bad feeding practices with a day in bed.

Know Thy Hay

So what is the right hay for your horse? All hay should be fresh-smelling and free of dust and mold. But looks can be deceiving.

First, hay can vary more than the buyer expects. For example, say an owner orders a load from a local farm and the horses thrive. The next year, with hay from the same farmer and same field, the horses refuse to eat more than a bare minimum and lose weight over the winter. Why the change?

Factors that affect the nutrition content and palatability of hay include:

  • Plant species-- A legume, such as alfalfa, has more protein than a grass hay, such as timothy. However, this can be misleading as a poor-quality alfalfa might have less protein than a good-quality grass hay.
  • Plant maturity--Just as baby carrots taste sweeter and are more tender than older carrots, plants become stringier and tougher with age. Hay is the same. As the cell wall material increases with growth, other nutrients decrease or are bound into the cell wall. A mature plant has a bigger, thicker stem and evidence of seeding. As the plant becomes more mature, crude protein (CP) decreases, which can make hay less suitable for some horses (young, growing horses), but better for others (mature, idle horses). When purchasing hay, buyers need to look for the type of hay that will meet their horse's needs. Hay that does not meet the nutrient requirements for a growing horse might meet all of the requirements for a mature horse that spends most of his time in the pasture.
  • Leafiness--This is related to maturity and is important in alfalfa hay. As the plant ages, the leaf-to-stem ratio declines. Leafiness is also related to storage practices, as improper handling can cause leaves to fall off the stems.
  • Environmental conditions--More sun equals more sugar. Also, the faster the growth, the more stem and leaves, and the higher the percentage of less digestible parts.
  • Fertilization--Nitrogen increases plant production and protein content in grass.
  • Water availability--The less water the plant gets, the slower the growth rate, but the higher the digestibility because sugars accumulate. Drought-stressed grass also can be high in sugars that could adversely affect founder-prone horses.
  • Time of year--First cuttings in spring come after cool temperatures and short--but increasing--days. Under these conditions, plants do not create as much lignin, a non-digestible substance, thus making the hay a better quality. Summer grass has hot temperatures and long days, leading to lower-quality hay. Fall is back to cooler temperatures and short days, creating hay where sugars accumulate in stem bases and stolons for reserves to help the grass survive the approaching winter.
  • Time of cutting--Plants photosynthesize sunlight into sugar during the day. Therefore, they will be higher in sugar and more palatable, though more risky for a horse with insulin resistance, if cut in the afternoon.
  • Storage practices--Heating, fermentation, and moisture damage are extreme results of bad storage. Even good storage practices can lead to nutrition loss as hay ages and dries out over time.


So what's a hay buyer to do? Test. A reputable hay seller should be willing to work with a buyer on proving the quality of the hay for sale. Some growers test hay themselves, either with the first cutting or with every cutting.

What tests can tell about a hay sample:

  • Dry matter content--A sample is heated to determine the percent of the sample that evaporates. That percent, say 10%, is water; what remains is the dry matter content.
  • Crude protein (CP)--To get CP, one measures the nitrogen in a sample, then calculates the protein assuming all protein is 16% nitrogen. The quality of protein is not measured. Hay with a higher CP is considered higher quality until it gets too high, which can mean it is full of unaccumulated nitrogen as nitrate. Hay can be tested for nitrate for around $7-$8 per test.
  • Crude fiber (CF)--Boiling the sample in weak acid, then in weak alkali, removes soluble carbohydrates and leaves the fiber and minerals. This test does not indicate how much is structural carbohydrates and therefore is indigestible or slowly digestible. As CF goes up, quality goes down. This is the old method of determining cell wall content, which is now determined by neutral detergent fiber (see below). Crude fiber is a poor estimate of forage feeds and overestimates forage energy content.
  • Neutral detergent fiber (NDF)--NDF contains cellulose, hemicellulose, and lignin. High NDF indicates high plant maturity and therefore lower quality.
  • Acid detergent fiber (ADF)--ADF contains cellulose and lignin and represents the more indigestible fraction of NDF. NDF-ADF=hemicellulose, a slowly fermentable source of energy that is very suitable for horses with less energy requirements.
  • Crude fat--Estimates fat-soluble lipids, but not how much of this fat the horse will digest.
  • Minerals--This testing is not very expensive and is an important factor to determine for balancing the diet for minerals or preventing excessive intake of certain minerals that might lead to disease problems (i.e., potassium levels in feed for horses with hyperkalemic periodic paralysis, or HYPP).
  • Energy--Energy from carbohydrates, fats, and protein is calculated from fiber and protein tests.

There are also less common tests for sugars in hay. These tests would be appropriate for horses with dietary issues, such as those suffering from Cushing's disease or prone to founder.

Van Saun suggests, "One needs to contact a number of labs and ask questions concerning methods used, quality control validation, retesting procedures, and costs. Once identified, use one lab consistently."

Know Thy Seller

Picture this scenario: A horse owner driving down the road sees an 18-wheeler parked at an intersection selling hay. The hay looks good, and the deal is great, so the owner loads up. Back at the barn, half the bales turn out to be moldy on the inside. Back at the intersection, the 18-wheeler is long gone.

That's not to say that all hay sold off the back of a truck is bad or a bad deal. In St. Petersburg, Fla., hay sales at the side of the road are common as truckers hauling citrus out of Florida often bring back a load of hay. But even if the hay is wonderful, it might not be wonderful for a particular set of horses. Nor is there any consistency from lot to lot.

This is why Don Kieffer, executive director of the National Hay Association (NHA,, recommends establishing a working relationship with a reputable hay seller.

"Locate a supplier who has the quality and type you require," says Kieffer. In any good working relationship, each party knows what the other is expecting. A hay seller should understand the buyer's particular requirements: A high-fiber hay if the barn's boarders are mostly Sunday riders, or perhaps some alfalfa mixed in if it's a show barn with harder-working horses. For backyard horse owners who only purchase small amounts of hay, Kieffer recommends establishing the same relationship with a good feed or tack store that buys from a reputable dealer.

In states where hay isn't frequently sold off the back of a truck, there are still ways to end up with inferior hay. "Hay buyers who only buy on price often have no idea how to get a settlement if things go wrong," says Kieffer. "This happens a lot, then they get mad at all hay sellers."

If bales are bad, a reputable dealer should make an adjustment so you are not left holding the bag, or bale.

Kieffer laments, "People pay thousands for a horse, then look for the cheapest feed they can buy. I don't understand this."

Kieffer also advocates buying by the ton, or pound. The weight of a bale of hay can vary from 40 to 70 pounds. Even the difference from a 50-pound to a 55-pound bale is a difference of 10%. Although many of us will scrutinize every label in the supermarket to get the best deal, some of us buy hay without any idea of the unit being sold.

A reputable hay seller or dealer is one who has been in business for a while and understands the clients. The good ones probably already have a reputation in your area.

The NHA is a trade association of commercial hay sellers. In existence for 109 years, it is one of the oldest trade associations in the United States. Eighty percent of the members are commercial hay sellers. Kieffer estimates that well over two-thirds of hay sellers by volume belong to the NHA. There are also many unaffiliated hay growers who only sell a few hundred tons a year. NHA members sell thousands or hundreds of thousands of tons a year.

Know Where To Get Help

As an extension veterinarian, Van Saun spends a majority of his time getting the word out. All states have an extension program. Horse owners looking for information can start with county programs or with their state's land grant colleges to see what help is available. Or, this being the 21st Century, type the name of the state and "extension veterinarian" into an Internet search.

There are many ways to get bad hay, or hay not suitable for your horse. To avoid that scenario, first educate yourself as to what you need, then seek out reputable sellers or enlist the aid of experts, such as forage specialists, to get the right hay. All hay is not the same, and neither are all horses--your horse will appreciate your efforts to get the best quality for his needs.



FEED INTAKE: How Much Forage Does Your Horse Need?

Maintenance 1.5-2.0% 90-100%
Gestating mare 1.5-2.0% 80%
Lactation 2.0-3.0% 70-80%
Growing horses (weanling) 2.0-3.0% 50%
Work 1.5-3.0% 65%

Adapted from The Nutrition Requirements of Horses, National Research Council, 1989.

HAY GRADING: What to Look For When Buying Hay

While laboratory analysis is the only way to get an exact idea of the nutrients in hay, its look, smell, and feel can help give you an idea of its quality. Keep in mind that "quality" is subjective--the quality of hay required by one horse to meet his needs is different from another horse. Forage specialists at the University of Kentucky created a guide for horse owners to use when purchasing hay to make sure the buyer is receiving the best possible hay.

Note: If your horse is laminitic or has a metabolic disorder that makes him sensitive to rich, high-carbohydrate hay, it's best to have his hay tested before buying. With variations in growing conditions, hay samples can look exactly the same, but have very different
carbohydrate levels.


Stage of harvest Before blossom or heading 26-30  
  Early blossom or early heading 21-25  
  Mid- to late bloom or head 16-20  
  Seed to stage 11-15  
Leafiness Very leafy 26-30  
  Leafy 21-25  
  Slightly stemmy 16-20  
  Stemmy 0-6  
Color Natural green color of crop 13-15  
  Light green 10-12  
  Yellow to slightly browning 7-9  
  Brown or black 0-6  
Odor Clean, fresh odor 13-15  
  Dusty 10-12  
  Moldy 7-9  
  Burnt 0-6  
Softness Very soft and palatable 9-10  
  Soft 7-8  
  Slightly harsh 5-6  
  Harsh, brittle 0-4  


Penalties Trash, weeds, dirt, etc. Subtract 0-35  




Scoring: 90 and above=Excellent hay; 80-89=Good hay; 65-79=Fair hay; Below 65=Poor hay

Adapted from "Quality Hay Production," Gerry Lacefield, Jimmy C. Henning, Mike Collins, and Larry Swetnam of the University of Kentucky.

FORAGE TESTING: Advice from a Test Lab

Editor's Note: The following advice comes from Debra Day, Kentucky Department of Agriculture Forage Testing Program.

Anyone buying, selling, or feeding hay should have hay tested. Hay is one of the least expensive feedstuffs available. If an individual selects hay based on a nutritionally balanced feeding program, the hay can be used to meet the nutritional requirements on a least-cost basis.

We include an information sheet called Interpreting Forage Quality Reports when we mail the nutritional results. The information sheet is published by the University of Kentucky and is written by their forage and dairy specialists. It includes definitions of nutritional terms and how the information relates to meeting livestock nutritional requirements. We also recommend that they call their county extension agents for assistance in balancing a ration.

The test results are only as good as how the sample was collected. It is important to randomly sample 15-20 bales per sample. This is most effectively done with a hay probe designed to take a core sample. If you need specialized testing such as endophyte, mineral, or toxicity, make sure that the laboratory has those capabilities beforehand.--Katherine Walcott

About the Author

Katherine Walcott

Katherine Walcott is a freelance writer living in the countryside near Birmingham, Al. She writes for anyone she can talk into paying her and rides whatever disciplines she can talk her horses into doing.

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