How to Interpret Your Hay Analysis Report: The Basics

By Juliet M. Getty, Ph.D.

One of the best ways to evaluate your horse's diet is to know what is in your hay. If you purchase at least two or more months' worth of hay at a time, it is worth having it analyzed.  Your local county extension service may offer analysis services, or consider Equi-Analytical Laboratories for assistance (www.equi-analytical.com).

Common terms and what they mean for your horse

Crude protein (CP) --  an estimation of total protein based on the amount of nitrogen in the hay. It does not tell you anything about the amino acid composition or the protein quality. To create a high quality protein, one that will help your horse maintain and repair tissue, combine a grass hay with a lesser amount of a legume (typically alfalfa). Most grass hay contains 8 to 10% CP whereas legumes (e.g., alfalfa, clover, perennial peanut) can range from 17-20%. Grain hays (oat, rye) generally have a lower CP than grass hay.

Acid detergent fiber (ADF) and Neutral Detergent fiber (NDF) -- both measure fibers (there are 5 types). Since fibers are digested by the microbes living in the hindgut (cecum and large colon),  a healthy microbial population is important for your horse to derive calories from fiber. However, there is one type of fiber that is indigestible - lignin. Lignin is increased as the plant matures. The higher these two values, the more lignin the hay contains. This means that your horse is not able to thrive on this hay since much of it ends up in the manure.  The ideal ADF is less than 31%; ideal NDF is less than 50%. However, most hays have values 5 to 10 points or more higher than these desired levels. To compensate, more hay needs to be consumed. This can be easily solved by allowing your horse to have free access to hay 24 hours a day. 

Non-Structural Carbohydrates (NSC) --  the total amount of sugar, starch, and fructan. To obtain %NSC, add together %WSC (water soluble carbohydrates) + %Starch. If your horse needs to have a low sugar/low starch diet, the %NSC should be <13% on a dry matter basis.

Water-soluble carbohydrates (WSC) --  measures simple sugars and fructan levels. Simple sugars are digested in the foregut and raise insulin levels. Too much can lead to laminitis because of elevated blood insulin. Fructan, on the other hand, is digested in the hind gut. Too much can result in laminitis caused by endotoxins in the bloodstream.

Ethanol-soluble carbohydrates (ESC) --  a subset of WSC and gives you a better idea of the simple sugar level. WSC minus ESC provides a fair measurement of fructan levels.

Starch --  normally digested in the foregut down to individual glucose (blood sugar) molecules; therefore, it has a strong elevating effect on blood insulin levels.

ESC + Starch should be less than 11% on a dry matter basis for a horse with equine metabolic syndrome or PPID (Cushing's).

Minerals

  • Calcium to phosphorus ratio -- There needs to be more calcium than phosphorus in hay. Most hay (except orchardgrass) will have this balance. The ideal ratio is 2:1, but the level of calcium can be even higher and still be considered safe. Phosphorus concentration must never be higher than calcium levels.
  • Calcium to magnesium ratio -- Ideally, calcium content should not be more than twice that of magnesium. Most hays have a magnesium level that is lower than what horses ideally require and that magnesium is not well absorbed.
  • Iron, Zinc, Copper, and Manganese -- Ideal ratios are Iron:Zinc -- no more than 5 times more iron than zinc;  Copper:Zinc:Manganese -- 1:3:3.  However, keep in mind that minerals interact with one another, interfering with absorption. Therefore, be conservative when supplementing minerals if your hay is close to these ideal ratios.
  • Selenium -- this is worth analyzing, since selenium has a narrow range of safety. Too little can be just as damaging as too much, so know your hay's selenium level before you supplement.

For Permission to Reprint

For permission to reprint this article, in part or in its entirety, please contact Dr. Juliet Getty directly at Gettyequinenutrition@gmail.com.