Interpreting an Equine Hay Analysis

Most universities and equine nutritionists encourage horse owners to have their hay tested. However, most horse owners need help interpreting the results of their analysis. Below is a list of some of the primary components commonly analyzed for in hay, and a basic interpretation of each. Keep in mind that additional components can be analyzed for by request (and/or for an additional cost) and that each laboratory will have a unique display of results. Also, remember the analysis you receive is only as good as the sample you submit. For more information on taking a hay sample, click here.

As Sampled vs. Dry Matter Results

When your sample is returned, there will be two main columns of numbers; As Sampled and Dry Matter. As sampled reports nutrients in their natural state, including moisture. Dry matter reports nutrients with the moisture removed. Results reported as dry matter allow for the direct comparison of nutrients across different feeds and often simplifies the ration balancing process; therefore, we recommend owners use the percent dry matter column. In this example, this is the third column of numbers.

Moisture
The optimum moisture for horse hay ranges from 10 to 15%. Hay under 10% may be too dry, leading to brittle hay. Hays over 17% moisture have an increased risk of molding (unless propionic acid is used), and hays over 25% moisture pose the threat of severe heat damage and serve as a potential fire hazard. In the above example, the moisture of this hay is 7.8% (moisture is usually listed above the other components at the top of the report). Please note, this hay was used for a research trial, so was dried prior to analysis.

Equine Digestible Energy (DE)
DE is the measure of the digestible energy in the hay and is used to balance the energy portion of the equine diet. Most hays range from 0.76 to 0.94 Mcal/lb of DE. Different classes of horses require different amounts of DE. For example, a light working horse requires approximately 20 Mcal/day of DE. In the above example, the hay has 0.92 Mcal/lb of DE. If this hay was used to feed a horse in light work, 22 pounds of hay each day would be needed to meet the horse’s energy requirement (20 Mcal/0.92 Mcal per lb/= 22 pounds). Make sure you request an equine DE when having horse hay analyzed as sometimes the default DE calculation is for cattle.

Crude Protein (CP)
Crude protein is a measure of the protein concentration in the hay. Crude protein can range from 8 to 14% in grass hays, 14 to 17% in mixed hays, and 15 to >20% in legume hays. Hay containing approximately 12% CP is thought to meet the amino acid requirements of most adult, idle horses. Other groups of horses (e.g. lactating mares, horses in heavy work, and foals) require greater amounts of CP. If feeding hay with less than 12% CP, supplemental protein sources will likely be required. In the above example, the hay has 15.1% CP.

Acid Detergent Fiber (ADF)
ADF represents cellulose and lignin, the highly indigestible fractions of plant material. The lower the ADF value, the more digestible the nutrients in the hay are. Hays with ADF values of 30 to 35% are readily digested, while those above 45% are appropriate for feeding horses with lower energy needs (e.g. horses at maintenance). In the above example, the hay has 35.9% ADF and nutrients should be readily digested by the horse.

Neutral Detergent Fiber (NDF)
NDF is a measurement of the insoluble fiber and is classified as cell wall or structural carbohydrates. These components provide the plant with structural rigidity. The higher the NDF, the less a horse will consume; it is generally accepted as an indicator of preference. NDF levels between 40 and 50% represent hays that will be highly palatable, while those above 65% will likely not be readily consumed by most horses. However, high NDF hays can be used as “busy hays”. Both ADF and NDF can be used to help determine maturity; the higher the values, the more mature that hay tends to be. In the above example, the hay has 64.8% ADF and will likely be more slowly consumed by horses.

Non Structural Carbohydrates (NSC)
NSC is an analysis of the starches and sugars in the forage. NSC is commonly estimated by adding starch and water-soluble carbohydrates (WSC). Since some horses are very sensitive to dietary starch and sugar (e.g. horses with laminitis and metabolic syndrome), the NSC level can be helpful in selecting hay. Hays containing greater than 12% NSC should not be fed to horses diagnosed with metabolic syndromes, while NSC is rarely a concern for healthy horses. In the above example, there is 5.3% WSC and 0.9% starch for an estimated NSC of 6.2%. This example is teff hay, an annual warm-season grass becoming popular among owners managing laminitic and metabolic horses.

Calcium (Ca) and Phosphorus (P)
Ca and P are two macrominerals required in the diet by all horses in specific amounts. The levels of these minerals can vary among different types of hay. For example, legume hays have high Ca levels relative to P. For the adult, maintenance horse, the Ca:P ratio should be between 3:1 to 1:1. In the above example, the hay has 0.44% Ca and 0.39% P for a Ca:P ratio of 1.13:1. Additional minerals can be tested for if necessary.

Relative Feed Value (RFV)
RFV can be used when selecting hay but is not used in balancing equine rations. Generally speaking, higher RFV reflects higher quality, greater intake, and digestibility. An “average” hay has a RFV of 100 and most agree would be suited for horses in light work. In the above example, the RFV is 87% indicating this hay would be best suited for adult horses at maintenance.

Written by Krishona Martinson, PhD, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Ask the Expert: Feeding Preservative Treated Hay

Photo Credit: Krishona Martinson, PhD, University of Minnesota

Question: Our regular hay supplier applied a preservative (propionic acid) to the bales this year. What is that and is it safe for horses?   

Answer: Preservatives are commonly used during times of frequent rainfall or poor drying conditions (e.g. high humidity or heavy dew). Propionic and acetic acids are commonly used hay preservative that are applied to hay as it is baled to allow baling of wetter than normal hay without spoiling during storage. Moisture at the time of baling is directly related to mold formation. Hay baled at ≤15% moisture is unlike to mold; however this is impacted by bale-type and mass. For example, small square bales can be baled up to 18% moisture with limited risk of mold formation; however, large round bales must be baled at ≤15% moisture to reduce the risk of mold formation. Preservatives are most effective at inhibiting mold growth, and most economical, when the hay is baled between 18 to 25% moisture. 

Preservatives are safe for use in horse hay. Researchers found that when given a choice, horses preferred hay that was not treated with a preservative; however, horses readily consumed the treated hay when a choice was not given. Yearlings receiving hay treated with a preservative consumed and gained just as much as yearlings consuming untreated hay, and clinical measures of well-being were not affected by consumption of preservative-treated hay. Interestingly, a horse’s hindgut bacteria actually make propionic acid as a result of microbial fermentation.

Therefore, feeding horses hay treated with a preservative is a safe and common practice, especially in years when poor weather conditions exist for making hay, and helps to inhibit mold growth during storage.

Written by Krishona Martinson, PhD, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Hoary Alyssum in Hay – Ask the Expert

Hoary Alyssum in HayQuestion: We suspect we have hoary alyssum in our hay. We’ve noticed our horses are stocked-up, but we are not sure if its from hoary alyssum or because all of the snow is limiting their ability to walk around. Can you confirm if this is hoary alyssym in our hay?

Answer: Yes, hoary alyssum is in this hay.

One seed head is circled in red and more can be seen throughout the photo.

Hoary Alyssum can be identified by small, oval seed pods that become translucent as they mature showing the small brown to black colored seeds inside the pods.

We recommend you immediately stop feeding the hoary alyssum-infested hay. Hoary alyssum only affects horses, so the hay can be fed to cattle, sheep and goats.

Horses can react differently to hoary alyssum, but signs of toxicity are usually seen 12 to 24 hours after a horse ingests the plant.

Common signs include swelling and fluid build-up in the lower legs (e.g. “stocking-up”), a fever of 103F or higher, stiff joints, and an unwillingness to move. More severe cases can progress to laminitis.

Mild stocking up is most common; however, more severe signs can occur in horses eating hay with more hoary alyssum or when ingesting the hoary alyssum-infested hay for longer periods of time.

Clinical signs normally go away with supportive treatment 2 to 4 days after removing the infested hay. Horses with laminitis may take more time to recover.

For more information on hoary alyssum toxicity, click here.

Written by Krishona Martinson, PhD, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Tips on Growing and Selling Horse Hay

Five horse hay growers in Minnesota share their tips on growing and selling horse hay, including how they monitor moisture throughout the baling process, how they work around the weather, what types of forages they grow and the investment it takes to grow and harvest hay.

The farmers also share their advice for individuals wanting to grow and/or sell horse hay and their greatest challenges associated with growing and selling horse hay.

This video was shared with permission from Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

How To Identify Moldy Hay – Ask the Expert: Testing for Moldy Hay

Our friends at the University of Minnesota Extension have helped to answer the question, how do you know if your hay is moldy? Equine expert Krishona Martinson, PhD, offers some tips below when it comes to hay testing.

Question:  I recently purchased some hay. I thought it was good quality, but I think the hay might be a little moldy. Can I test my hay for mold?

Response: Most forage testing laboratories can test hay (and other feed stuffs) for different types and amounts of molds. The costs average $40 and takes about one week to complete. The sample is collected and submitted similar to a hay analysis for nutrient value.

Watch a YouTube video on how to collect a hay sample.

All hay will have some mold; no sample will have zero mold. Mold spore counts are given in colony forming units per gram (cfu/g). Hay with less than 500,000 cfu/g of mold is considered good quality.

Hay with 500,00 to 1 million cfu/g is relatively safe, while hay with over 1 million cfu/g of mold should not be fed to horses due to the risk of respiratory issues. Most people can start to detect mold around 500,000 cfu/g.

If your hay is between 500,000 and 1 million cfu/g of mold, use precaution by pulling flakes apart before feeding, feeding outside or in a well-ventilated area, using a hay net to restrict the horses ability to bury their nose into the hay, and wetting the hay to reduce the amount of mold spores inhaled.

Alternatively, you could look for a better quality hay or ask your hay supplier to exchange the hay for bales with a lower mold count.

This article is reprinted with permission from Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Glycemic Response to Soaked Hay

Horse HayFor horses diagnosed with Equine Metabolic Syndrome, obesity, laminitis and/or insulin resistance, the need for dietary management of nonstructural carbohydrate intake is necessary. One management tool horse owners can use is regulating the glycemic response in diseased horses, which is the effect food has on blood glucose levels after a meal. Past research has shown that soaking hay for 30 to 60 minutes reduces nonstructural carbohydrate levels; however, researchers have yet to explore if hay soaking has an effect on glycemic response. Recently, researchers at Middle Tennessee State University examined how soaked hay versus non‐soaked hay affected the glycemic response in horses.

Two different hay types were evaluated both as soaked hay and non-soaked hay; prairie grass and alfalfa. Wet hays were soaked in cold water for 60 minutes and 12 healthy horses (average of 17 years and 1,207 pounds) were fed the hays. Blood samples were taken immediately at the time of feeding and every 30 minutes for 2 hours, and every 60 minutes up to 5 hours.

Researchers found that horses had a higher glycemic response to alfalfa hay compared to prairie grass hay. However, there was no difference in the glycemic response to non‐soaked or soaked hay of either type. Over time, plasma glucose levels were higher in horses fed alfalfa versus grass hay.

Researchers concluded that although the type of hay fed influenced the glycemic response, no difference in physiological glycemic response was observed in healthy horses fed non-soaked or soaked hay. Additional research is needed to determine if soaking hay has physiological merit in horses diagnosed with Equine Metabolic Syndrome, obesity, laminitis and/or insulin resistance.

For more information on this study, click here.

For more information on hay soaking, click here.

Summarized by: Devan Catalano, BS, University of Minnesota.

This article is reprinted with permission from Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

Estimating Winter Hay Needs

Cooper and Ferris in a snowstorm

Question: We recently purchased a farm and will be housing our two quarter horses over the winter. They are trail horses who are not ridden during the winter. Because I’ve always boarded my horses, I’m not sure how to estimate how much hay I will need for the winter. Can you provide some guidelines?

Response: An adult horse at maintenance will consume between 2 – 2.5% of their bodyweight in feed (hay and grain) each day. For example, a 1,000 pound horse fed a 100% hay diet would consume 25 pounds of hay each day.

  • From October 15 to May 15 (when there is no pasture in MN), the horse would consume about 5,350 pounds of hay or 2.7 tons.
  • This would equal 107 fifty pound small square‐bales or six 900 pound round‐bales during this time.
  • For two horses, this amount would be doubled; 214 small squarebales or 12 round‐bales.
  • It is critical to know the weight of the hay bales; not all bales weigh the same.

If the same horse was receiving 5 pounds of grain each day, their hay needs would be reduced to 20 pounds each day.

  • From October 15 to May 15 the horse would consume about 4,280 pounds of hay or 2.1 tons.
  • This would equal 86 fifty pound small square‐bales or five 900 pound round‐bales during this time.
  • For two horses, this amount would be doubled; 172 small‐square bales or 10 round‐bales.

These estimates assume good quality hay is fed in a feeder to reduced hay waste. When feeding small squares‐bales, hay waste when a feeder was not used (hay fed on the ground) was approximately 13% compared to only 1 to 5% when a feeder was used. When feeding large round‐bales, not using a feeder resulted in 57% hay waste compared
to 5 to 33% hay waste when a feeder was used. Its always best to purchase some extra hay since horses may require additional hay during the cold winter months (depending on their access to shelter).

Author: Krishona Martinson, PhD, Univ. of Minnesota. Reprinted with permission of the author. For other topics from the Univ. of Minnesota Equine Extension, visit their website.

Determining the Value of Rained-On Hay

George eating hay in his paddockRain occurring while cut hay is laying in the field causes both yield and quality losses that reduce the value of the crop as an animal feed and a marketable commodity.

Weather-induced losses are caused by:

  1. Prolonged plant respiration reducing soluble carbohydrates and overall energy content
  2. Leaching of soluble carbohydrates, protein, and certain minerals from the hay
  3. Leaf shattering and loss, removing the highly digestible and high protein portion of the forage
  4. Microbial activity metabolizing soluble carbohydrates and reducing energy content
  5. Color bleaching

How much does rainfall reduce dry matter yield?

Several researchers have studied the effects of rainfall on cut alfalfa. Wisconsin researchers measured dry matter losses of 22% when alfalfa was exposed to 1 inch of rain after 1 day of drying (curing). Similar hay dried without rain damage lost only 6.3% of the initial yield. Losses appear to be greatest after partial drying of the forage has occurred. In this same study, alfalfa exposed to 1.6 inches of rain over several days suffered a 44% loss in dry matter. Michigan researchers conducted several different studies to examine the effects of rainfall on field cured alfalfa. The first study reported maximum dry matter losses of 34%. In a second study, rainfall intensity was kept constant at about 0.7 inches but spread over periods of 1 to 7 hours. Dry matter losses ranged from 4 to 13%, with highest losses occurring when the rain was spread over a longer duration. Overall, dry matter losses were much lower in these experiments even though rainfall amounts were about 2 inches.

Other species have been studies as well. Yields losses of birdsfoot trefoil appear to be less than alfalfa, while red clover shows even less dry matter loss due to rain, and grasses suffer the least amount of dry matter losses. Dry matter losses are most crucial to the person responsible for baling the hay. Dry matter losses usually represent a significant decrease in income since less hay is available for baling, feeding, and selling.

How does rainfall reduce dry matter yield?

Three primary factors are involved in dry matter losses; leaching, respiration, and leaf loss. Leaching is the movement of cell solubles out of the plant. Components of the plant that are very water soluble are leached out of the forage and lost when rain occurs. Unfortunately, most of these compounds are those highly digested by the animal. They include such components as readily available carbohydrates and soluble nitrogen, minerals, and lipids. About one-half of the dry matter leached by rain is soluble carbohydrates.

Unlike other livestock, losses of soluble carbohydrate can be beneficial for some horses. Laminitis is a painful and debilitating disease of the horse hoof. Laminitis typically occurs during periods of increased or rapid intake of water soluble and nonstructural carbohydrates. In order to manage lamintic horses and reduced amounts of carbohydrates in harvested forage, horse owners have resorted to soaking hay. A number of research trials have confirmed removal of carbohydrates from hay by soaking in either 30 minutes of warm or 60 minutes in cold tap water. Soaking hay is a cumbersome, messy, and time consuming process. Purchasing rained-on hay with naturally low levels of carbohydrates is a possible alternative.

Respiration (breakdown of soluble carbohydrates by plant enzymes) occurs at nearly 2% dry matter per hour in fresh forage, and declines almost in proportion to the decrease in moisture content until the plant reaches approximately 60% moisture. Every time the forage is wetted by rain, respiration is either prolonged or begins again in cases where the cured forage was below 60% moisture. In either case, additional dry matter is lost.

There is some disagreement in the research literature regarding the amount of leaf loss that occurs in cut alfalfa as a direct result of rainfall. In Wisconsin studies, leaf loss ranged from 8 to greater than 20% as a percent of the initial forage dry matter when rainfall amounts were from 1 to 2.5 inches. In Michigan studies, direct leaf loss was much lower (0.5 to 4.2%). Perhaps the issue of leaf loss from rainfall is a mute point. Experience and common sense tell us that rain damaged alfalfa is more predisposed to leaf shatter after it dries, and rainfall often means additional raking and more lost leaves.

How does rainfall intensity and forage moisture affect losses?

Research is conclusive on these two points. Given the same amount of total rainfall, a low intensity rain will result in more leaching of soluble compounds than a high intensity rain. Also, as forage moisture content declines, it is more prone to dry matter loss from rain. In Wisconsin rainfall studies, the maximum loss in dry matter (54%) was a treatment where 2.5 inches of rain fell on hay that was nearly dried.

How does rainfall affect forage quality?

Perhaps nothing is more frustrating than to see excellent quality alfalfa turn into unsuitable feed with each passing rain and subsequent raking. Most rainfall studies are in agreement that wetting of field dried alfalfa has little impact on protein concentration. For rained-on hay, it is common to see relatively high protein values in comparison to fiber concentrations, unless significant leaf loss occurs. With the leaching of soluble carbohydrates, structural fibers (acid and neutral detergent fibers) comprise a greater percent of the forage dry matter. Depending on numerous factors, the digestibility of rained-on hay may decline from 6 to 40%. Changes in fiber components are thought to occur by indirect mechanisms, where the respiratory activity of microorganisms has a concentrating effect on fiber components by oxidizing carbohydrate components; additional fiber is not made during the wetting process.

Conclusion

Rained on hay can be a suitable forage, but quality depends on several factors. Forage quality tends to be retained if rain occurs soon after cutting when the forage has had minimal time to dry; the rainfall was a single event compared to a multiple day or drawn-out event; rainfall intensity was higher versus a longer, lower intensity event; and the forage has not been re-wetter numerous times. Rained on hay is actually beneficial for horses prone to laminitis and other metabolic disorders because of its reduced carbohydrate content. Analyzing forage for nutrient content is recommended, but can be especially useful when determining the quality of rained on hay.

This article is reprinted with permission from Dan Undersander, University of Wisconsin and Krishona Martinson, University of Minnesota. This and other horse nutrition articles can be found at http://www.extension.umn.edu/agriculture/horse/nutrition/.

How to Transition a Horse’s Feed

You may be thinking your horse might be in need of a senior diet, or perhaps there is a new feed available that you believe is even better for your horse.  Maybe you are no longer happy with your current feed.  Or, your dealer no longer carries the product you were using.  Whatever the reason, switching your horse to a new feed is a change that requires care and know-how. 

Changes to feed, pasture or hay in general should be made over a 7 day period, gradually increasing the new and decreasing the old.  For example:

Day 1: 80% of old feed / 20% of new feed

Day 2: 70% of old feed / 30% of new feed

Day 3: 60% of old feed / 40% of new feed

Day 4: 50% of each

Day 5: 40% of old feed / 60% of new feed

Day 6: 30% of old feed / 70% of new feed

Day 7: 20% of old feed / 80% of new feed

Moving from a feed higher in Non-Structural Carbohydrates (NSC) to one that is lower can be done relatively easily by following the instructions above.  If you are moving your horse from a ‘low’ NSC feed to one that is higher in NSC, feed changes should happen over at least the 7 days recommended above, if not longer. 

Research has indicated that horses fed pre and probiotics are better able to handle changes in diet than horses that are not. 

Changes in hay, though generally not given much consideration, can have as much of an impact if not more than changes in feed. If possible, try to follow the same steps as above when transitioning your hay.  Hay that is harvested from the same field, but in different cuttings will likely vary in nutritional content. Hay testing is available from many University Extension offices.  Check with your area extension office for more information.