As we transition into fall, many of us are more reliant on hay as the primary forage for our horses as the grasses slowly die off or go into dormancy phase. In an attempt to “cover all the bases “ and in an effort to ensure that we are providing adequate minerals, vitamin, protein and energy in our horses’ diets, many of us feel we have to supplement with fortified feeds/grains. However, common questions that arise include:
“Are we really covering all the bases?”
“Does my forage address basic nutrient requirements?”
“Am I wasting money on fortified feeds and supplements that I really don’t need?”
More attention is being focused on testing our equine feeds and balancing accordingly. Since forages are the foundation of the equine diet and hay is the likely source of forages for the next several months that is the best place to start – with a basic forage test and subsequent forage report.
Start with an Accurate Sample
Forage test results are only as good as the sample submitted to the lab. While it is tempting to take random grab samples from a bale here and there, that is not the most accurate method of forage testing, as it is not likely to be a true representation of what your horse is actually eating. The best method of testing involves the use of a hay corer or probe attached to a drill that can core through the cross section of a bale. If you do not have access to a hay corer/probe, contact your local Cooperative Extension office or feed store to see if they have one you can borrow or rent. If you plan to test on a frequent basis, it might be worth investing in one such as the hay corer/probe the Penn State Sampler.
The next step is to identify a lot or load of hay all coming from the same field and cutting. You will need to core a minimum of 15-20 bales to get a good representation of the lot for testing purposes. You will also need something to put your forage sample in as you core your bales. I recommend a plastic bucket and then transferring the samples to a Ziploc sealable bag once you are done with the collection process.
Choose the Right Lab
Labs that participate in the National Forage Testing Association (NFTA) certifying program have undergone outside scrutiny and been found to present the forage data with a certain acceptable range of accuracy depending on the primary forage testing methods used.
It is noteworthy to point out that many of the labs are analyzing feeds for ruminant animals, not horses. So an important question to ask up front is whether the lab does a forage analysis specific to horses, as many of the ruminant reports will not address digestible energy, starch and/or specific minerals in their analysis.
What Does it All Mean?
When looking at an equine forage report, there are a number of values that should be reported -- Dry Matter (DM), Digestible Energy (DE), Crude Protein (CP), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), Water Soluble Carbohydrates (WSC), Ethanol Soluble Carbohydrates (ESC), Starch, Fat, Calcium (Ca), Phosphorus (P), Magnesium (Mg), Potassium (K), Sodium (Na), Iron (Fe), Zinc (Zn), Copper (Cu) and Manganese (Mn).
The first thing you should look at is the Dry Matter (%DM). Ideally, for hay, the %DM should be equal to or greater than 85%. Anything less than 85% should raise concern that the hay was not properly harvested.
When looking at hay samples we commonly look at the 'As Sampled' column. You will note that ‘As Sampled’ values are lower than the ‘Dry Matter’ values. This is because the ‘Dry Matter’ values have the moisture removed.
Digestible Energy (DE) is the caloric yield of forages and commonly reported in Mcal/lb. Most quality grass hays are going to be between 0.85 and 0.95 Mcal/lb on an ‘As Sampled’ basis. The DE for fresh grass and harvested legume forages will be a bit higher. Horses in moderate work need roughly 20-25 Mcal per day.
Crude Protein (CP) is typically reported on a percent (%) basis and sometimes on a grams/lb basis. Crude protein should be measured in grams per day, not %, and the average 1000 horse in moderate work would requires ~700 grams of CP per day. On a percent basis, the %CP of most grass forages will range from 8 to 12% CP; whereas, legume forages will average much higher. A grass hay with 10% CP fed at 2% of body weight is meeting or exceeding CP requirements.
Acid Detergent Fiber (ADF) of hay is the portion comprised of cellulose and lignin. It gives an estimate of how much energy the horse can derive from the hay and is generally reported in % form. Anything <31% is excellent; >45% is of poor quality.
Neutral Detergent Fiber (NDF) is a measure of insoluble fiber and includes all of the cell wall carbohydrates- lignin, cellulose, and hemicellulose. Lignin is indigestible, but hemicellulose and cellulose can be partially digested by microorganisms in the hindgut. It is also an indirect measure of palatability or intake potential and measured in % form; < 40% is excellent; >60-65% is of poor quality.
Nonstructural Carbohydrates (NSCs) are technically calculated by adding water soluble carbohydrates (WSC) + Starch. Again, we generally look at the % column, but in certain situations it may be useful to look at the total grams/lb. For more sensitive or metabolically challenged horses, it may be more accurate to look at ethanol soluble carbohydrates (ESC) + Starch. If you are interested in these values, be sure to select a forage analysis that includes WSC, ESC and starch.
Fat percentages are often reported in % and are generally low in forages, often under 4%.
The macro minerals – calcium (Ca),phosphorus (P), potassium (K) and sodium (Na)– will be reported in % or g/lb.
Calcium (Ca) to Phosphorus (P) Ratio – Calcium and phosphorus are the main structural components that make up bones and teeth. There needs to be more calcium than phosphorus in hay. The ideal calcium:phoshorus ratio in the equine diet is 1.2-2:1 for most mature performance horses.
Calcium (Ca) to Magnesium (Mg) Ratio – Ideally, calcium content should be no more than twice that of magnesium.
You also need to make sure that the amount of calcium, phosphorus and magnesium supplied in the forages actually meet the basic requirements of the horse, which will vary by body weight, age and stage of production.
Potassium (K) – Forages are generally high in potassium and it is not uncommon to see values of 2+%. High potassium values may be of concern for certain horses, especially those that are HYPP positive.
Sodium (Na) – Often tested for but generally deficient in forages.
The trace minerals will be reported in ppm (mg/kg) or g/lb. Iron (Fe), Copper (Cu), Zinc (Zn) and Manganese (Mn) are often included in a standard trace mineral analysis. Most forages are naturally high in iron (occasionally high in manganese too) and generally deficient in essential copper and zinc. Extremely high iron can interfere with the absorption of other minerals like copper and zinc and should be balanced accordingly.
Take Home Message
Hay testing can be a valuable tool in assessing whether we are meeting our horse’s basic nutrient requirements. It can help us make appropriate decisions as to whether additional feeds and/or supplements are necessary as well as determine whether a specific forage is suitable for our horse. The 2007 Nutrient Requirements of Horses from the National Research Council (NRC) is a valuable resource for determining the concentration of different nutrients a horse requires and can be found online as a reference for comparison.
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