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/.

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/.

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/.

Changing Hay Sources for Horses

As a horse owner, I have moved quite a few horses around and recently moved my gelding to a new boarding facility, so thought this would be a good opportunity to share one aspect of my experience. 

To help maintain as much consistency in his routine as possible, I made sure that I had 2 weeks’ worth of hay to take with me to help keep his diet consistent throughout the move and to allow for a gradual transition to the new hay. 

When I told the barn managers at the new facility that I was bringing a few bales of hay over, they seemed a little surprised at this and told me not to worry about it, because they had really high quality hay.  I asked them if they would recommend a sudden change in a horse’s grain ration, and immediately they said of course not, due to colic risk. I replied, “Then why would you switch their hay cold turkey, when it makes up 60 – 70% of the horses diet?” and watched their expressions as they realized the point I was making.

As a result, along with keeping his grain ration and meal times consistent with the previous routine, a gradual transition from the previous hay to the new hay was done over a 2 week period.  For the first couple of days he received his “old” hay only, and over time we incrementally replaced a small portion of his “old hay” with the “new hay” so that at 2 weeks post-move, he was completely switched over without any problems or decline in performance. 

As horse owners, it is important to keep in mind that ANY sudden changes in diet, including fresh pasture and hay, can disrupt the environment in the gut where communities of microbes reside.  Consequently, this disruption in the microbial population and digestive process can put the horse at risk for GI upsets (e.g. excessive gas production, colic, diarrhea, discomfort, etc.). The energy and nutrient content in hay can vary drastically depending on the plant species, geography, soil conditions, plant maturity at harvest, climate conditions, baling and storage methods, etc.  Even hay that comes out of the same field from consecutive cuttings can have large differences in quality and nutrient content that should be considered. 

It takes approximately 3 weeks for the microbes in a horses gut to adapt to dietary changes, thus making slow, gradual transitions over a 2 – 3 week period important to help prevent GI upset.  When it isn’t possible to make a full two week transition, then allow for as much of a gradual transition as possible even if is only over 2 – 3 days.  Providing dietary pre- and probiotics can also help support gut microbes through dietary changes especially if they are rapid.

Judging Hay Quality for Horses

Because hay is such a common part of a horses diet, judging quality on visual inspection is important, as lab analysis is not always easily available.  Here are three simple things to look for to help you select the best hay for your horses and your money.

  1. The initial check that most people are familiar with is color and smell.  Horse hay should be bright green and smell slightly sweet.  Brown hay indicates either a problem in the baling process, such as being rained on, or age.  Acrid or musty smells generally indicate the presence of mold.
  2. Another sign of good horse hay is the leaf:stem ratio.  The more leaves, the better, since the leaves are where most of the nutrition in the hay is stored.  Hay that has too many hard, woody stems is difficult to digest.  Even if it cheaper, most horses will pick through and leave the bulk of the stems behind, costing more in the long run.  High quality hay is fine-stemmed, pliable, and full of leaves.
  3. Type of hay is another factor.  Grass hays, such as timothy or orchard grass, generally provide sound basic nutrition.  The higher the concentration of legumes, such as alfalfa or clover, the higher the energy content.  High quality alfalfa is generally better than high quality grass hay, but good quality grass hay can be better than average quality alfalfa hay.

The best thing, in the end, is to have hay tested.  This is not always feasible for every load, but if your hay source is consistent from load to load, this may be a good option to get a general feel for what nutrients your hay contains.