Hay is the main source of forage for many horses, especially if pasture is insufficient or not available. “Because hay often makes up such an important part of the diet, its nutritional value should be considered. A basic forage analysis can help horse owners and managers adjust concentrates and supplements based on the nutritional value of hay,” said Kathleen Crandell, Ph.D., a nutritionist at Kentucky Equine Research.
A hay analysis report typically lists results as both “as sampled” and as “dry matter” (DM). An “as sampled” analysis includes values for the forage in its natural state, whereas DM is the analysis with all of the water removed from the sample. DM analysis makes it easier to compare different samples to each other, regardless of water content.
Digestible energy (DE) is commonly expressed as Mcal/lb, or megacalories per pound. A megacalorie is equivalent to the calories we think of in human nutrition multiplied by 1,000. So, a feed that has 1.2 Mcal/lb contains 1,200 calories (or kilocalories, kcal).
Crude protein is another important number, and can indicate hay quality. Hay with very low protein, say 6-8%, is not likely to be of great quality. Good-quality alfalfa tends to have higher crude protein (18-24%), whereas grass hays are usually lower (10-18%).
In addition to energy and protein, it is critical to look at the basic mineral content, specifically calcium, phosphorus, zinc, copper, and iron. Mineral values are tied to soil mineral contentâ€”if a mineral is in the soil, it will probably be in the hay! There should be more calcium than phosphorus, making the calcium-to-phosphorus ratio no less than 1.2:1. Similarly, there should be more zinc than copper, with at least 3:1 to 5:1. High iron content can be an issue for absorption of other minerals, but it is rare unless fields receive a lot of industrial runoff.
Acid detergent fiber (ADF) and neutral detergent fiber (NDF) are also indicators of quality and digestibility. Typically, the higher the ADF, the lower the digestibility. The higher the NDF, the lower intake tends to be.
Basic hay analyses usually include a measure of carbohydrates: ethanol-soluble carbohydrates (ESC), water-soluble carbohydrates (WSC), and starch. ESC and WSC both measure simple sugars in a sample, but WSC measures fructans, which plants use for energy, and ESC does not. Examples of simple sugars include glucose and fructose. Starches are larger sugar molecules that are measured separately. To estimate nonstructural carbohydrates, or NSC, simply add starch and WSC.
Once hay is cut and harvested, vitamin E begins to break down. Hay that has been stored for longer than a few weeks is likely deficient, although a basic hay analysis may not provide that information. A good-quality vitamin E supplement, such as Nano-E, helps ensure the horse’s needs are met.
A hay analysis provides valuable insight and helps an equine nutritionist balance the ration precisely. If you don’t have a hay analysis available, don’t panic. Composite samples collected by laboratories are often used to estimate basic nutrient value, which can, in turn, be used to arrive at overall intake.
All of the acronyms, numbers, and calculations can be overwhelming. For that reason, Kentucky Equine Research nutrition advisors are trained to help with all the numbers and to make sure your horse’s diet is on track.