During your last trip to the grocery store, how many times did you pick up a package, flip it over, and read the nutritional guide on the back of the box?
Chances are you know how many calories are in a serving of your favorite snack. If you’re following a restricted diet, you also know how much protein, sugar, and carbohydrates it has.
Everyone pays attention to what they consume to a certain level, with some making a concerted effort to eat balanced meals.
Similarly, horse owners and trainers strive to provide their horses with balanced meals, including high-quality hay. But how many know what their horses are actually eating?
Hay typically makes up 75-100% of the horse’s diet, supplying the bulk of the daily nutrients. Unlike human food packages or manufactured feeds, it has no nutritional label.
“Forage testing gives the nutrient levels in the hay, so you have a place to start building a feeding program to meet the nutrient needs of the horses being fed,” says Robert Coleman, PhD, PAS, Equine Extension Specialist at the University of Kentucky Ag Equine Programs. “Since forages/hay are the basis for all the feeding programs for all classes of horse, testing the hay is a good place to start when developing a sound feeding program.”
With an increased focus on forage-first diets, knowing what a hay ration contributes to the overall nutrients in a horse’s diet is essential. This information is even more critical for metabolic horses.
“Hay testing is an important but often underutilized practice by horse owners,” says Catherine Whitehouse, MS, Equine Nutrition Advisor at Kentucky Equine Research. “A hay analysis can be useful when horses are not performing as expected and during consultation on nutritionally related health conditions such as insulin dysregulation and HYPP (hyperkalemic periodic paralysis), to help assess the forage suitability for these conditions based on the nutrient content.”
Veterinarians can play an important role in helping owners assess their horses’ hay and put forage test results to good use—that is if veterinarians themselves understand the information they’re working with.
What’s in the Hay?
A hay analysis confirms the amount of nutrients present in each batch of hay. Knowing the nutrients available from the hay allows owners, barn managers, and veterinarians to design feeding recommendations based on the horse’s age, health, and workload and fill in any nutritional gaps with feed or supplements.
“Proper forage feeding practices are essential to support horse health, welfare, and performance,” says Whitehouse, a PhD candidate at the University of Kentucky under the advisement of Laurie Lawrence, PhD. “With a completed hay analysis, veterinarians can discuss the nutrients provided by the hay and the need for any supplemental feeds. They can also discuss if a particular hay is the most appropriate for a specific type of horse.”
For the best results, have clients use a hay probe to collect samples from 20-25 bales in a single load. Hay from different suppliers and even hay cut from the same field at different times of the year can yield different results. A hay probe takes a core subsample from the center of the bale to ensure an accurate cross-section of the bale.
The collected sample is then packaged in plastic bags and sent to a lab for analysis. The resulting one-to-two-page report can be challenging to interpret—41.5% of veterinarians surveyed were very confident or confident in evaluating hay quality based on a forage analysis, according to a survey Whitehouse distributed to Kentucky Association of Equine Practitioners members.
“When looking at the analysis, there will be two columns,” Coleman says. “One being ‘as fed’ and one being ‘dry matter.’ When comparing two different analyses, the comparison is made using the dry matter values. You can use the as fed values when developing the feeding program.”
Here, Coleman breaks down the data supplied through a forage analysis:
Dry Matter / Moisture %
Moisture content provides essential information about how the hay was cured and baled. The higher the moisture content, the greater the chance for mold.
“A dry matter over 83.5 or a moisture 16.5 or less is reasonable and likely to reduce the risk of mold formation,” says Coleman.
Digestible Energy (DE) Mcals/lb
Digestible energy is an estimation of the calorie content, and the “ideal” amount depends on the individual horse.
“That said, I would like to see a DE value of 0.80-0.90 Mcal/lb as a comfortable range, knowing that the 0.80 is low, but for some horses that might be OK with proper management,” he says.
Crude Protein (CP) %
The protein content is calculated as % N x 6.25 on an equine hay analysis. Hay variety (legumes vs. grasses) and harvest season can influence the amount of CP. Young horses, horses in intense work, and lactating mares will likely need higher levels of CP than others.
Coleman finds 9-15% CP to be a reasonable range, with 15% much higher than most horses require.
Acid Detergent Fiber (ADF) %
ADF is one of two types of carbohydrates listed on a hay analysis. It reflects the hay’s fiber content and overall digestibility.
“I like ADF to be below 40%,” Coleman says.
Neutral Detergent Fiber (NDF) %
NDF is the other carbohydrate included in a forage analysis, and its presence can indicate the hay’s palatability.
“An NDF of over 60% on a dry matter basis can result in a reduced voluntary intake and possibly more hay not consumed,” he says.
Water Soluble Carbohydrate (WSC) and Starch %
“When added together, the (percentage of) WSC and starch on a dry matter basis indicates the nonstructural carbohydrate level,” Coleman explains. “For horses with metabolic issues, this number should be 10% or lower.”
Mineral Values
“Any mineral values are helpful and add to the overall nutritional information from the analysis,” he says. “If the hay comes from an area of a known trace mineral deficiency, getting additional trace mineral information is useful. Consider copper, zinc, manganese, and possibly selenium.”
Other Data
Depending on the laboratory and analysis selected, the report might also include the amount of fat (extract fat) and relative feed value (RFV).
Guiding Clients in Developing Equine Hay Rations
With a hay analysis in hand, you can use that information to advise clients on determining hay rations for their horse(s). Each horse is an individual, and its age, workload, and overall health become part of the equation.
“If you are feeding high-producing broodmares, important nutrients include crude protein, digestible energy, fiber content, and calcium and phosphorus,” Whitehouse says. “The fiber content (neutral detergent fiber, acid detergent fiber, and lignin) indicates how digestible the hay is and the potential level of voluntary intake. Higher crude protein, lower fiber levels, and higher digestible energy levels are desirable for these horses.”
In comparison, she says, when managing mature horses with metabolic disorders, especially those that are overweight, important nutrients include water-soluble carbohydrates (sugars), starch, and digestible energy.
“In this case, low sugar and starch levels and lower digestible energy values are desirable,” she says.
In addition to using information from a hay analysis, you can teach clients how to use a horse’s weight to determine hay ration.
Generally, nutritionists recommend feeding 2-2.5% of a horse’s body weight in forage unless the animal has specific concerns or needs, such as a lactating broodmare or a performance horse.
That means a 1,000-pound horse should receive between 20 and 25 pounds of forage daily, which can be a combination of hay and pasture or hay only, depending on the client’s management approach.
But most horse owners don’t have scales to weigh their horses. Scales are the easiest and most accurate tool for determining a horse’s weight. As an alternative, teaching horse owners how to use a combination of the horse’s measurements with this simple equation can help estimate how much their horse weighs so they can determine how much hay to feed:
- Measure the horse’s heart girth in inches.
- Measure the horse’s body length from the point of its shoulder to its rump.
- Plug the measurements in inches into this equation:
(heart girth2) x body length = weight in pounds
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As with any rule, there are exceptions. A horse’s age, breed, activity level, and body condition score might mean he needs a larger or smaller serving of hay. Young horses and broodmares might also deviate from these guidelines.
Answers to Common Client Questions
Horse owners often consider cutting (first, second, third) as a factor when assessing hay quality. Whitehouse, however, explains that the stage of plant maturity at harvesting, rather than cutting, determines the hay’s nutritional content and quality. Several studies have reported that few horse owners (often less than 20%) have their forage analyzed despite the benefits of the information it provides—helping build the best diet for their horses.
“Given horse owners’ limited experience with hay analyses, you may be asked several questions when you recommend completing one,” she says.
How much does forage testing cost?
Analysis packages range from $14 to $80 or more per sample, depending on the lab and package selected. Once submitted, the sample can be processed in one to five days.
Why am I spending money on forage testing?
Rations—forage, feed, and supplements— are the most expensive component of daily horse care. With a forage test, owners can understand if they are making the best use of their investment.
“Having the nutrient values allows for feeding programs to be developed that meet the needs of the horse,” Coleman says. “Horse owners can properly supplement nutrients to compensate for those not provided at a level that meets the horse’s requirements.”
A hay analysis can also be useful when horses are not performing as expected, Whitehouse adds. “A hay analysis in combination with hay intake data allows a comprehensive evaluation of the ration for potential problem areas,” she says.
How do I collect a representative sample?
A hay core sampler (hay probe) is the preferred method for collecting a representative sample from hay bales. As a general rule, sample at least 20 random bales of hay from a single lot. County extension offices/agents might have access to a hay probe to help collect a representative sample.
Where do I send the sample?
Cooperative extensions and commercial labs are available nationwide for hay analysis.
Which nutrient/analysis package should I request?
Hay analysis packages can differ between laboratories and methods of analysis, so it is important to know what information is needed to request/submit a sample.
Take-Home Message
Hay is the most expensive daily investment for clients and the core component of most horses’ daily rations. Helping clients understand the nutrient value of the hay they’re buying helps ensure they’re making the most of their purchase and providing their horse with the optimum diet.
“If the hay supply is relatively small and/or changes frequently, a hay test will not be as informative and may not be recommended, but it may be worthwhile asking if an analysis is available from the hay producer or retailer/supplier,” Whitehouse says.
Reference
1 Kenny, L.B., and D.N. Smarsh. 2024. Characterizing hay buying and feeding practices and attitudes among Pennsylvania horse owners. Journal of Equine Veterinary Science: doi: 10.1016/j.jevs.2024.105147.
Related Reading
- Use of Oat Straw to Manage Equine Obesity
- What Clients Want to Know About Hay
- Nutritional Management of the Competitive Equine Athlete
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