by Haley Ruffner
24 August 2022 | [email protected] | 307.205.6628
While not all farmers test their hay, a basic hay analysis is very useful to both farmer and end user in marking the quality of the hay and its value to customers. A typical analysis will include readings on moisture, crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), relative feed value (RFV), horse digestible energy (DE), calcium and phosphorus (Ca and P), fat, starch, ethanol soluble carbohydrates (ESC), water soluble carbohydrates (WSC), and non-structural carbohydrates (NSC). Each of these factors are typically measured in two columns: as sampled and dry matter. The dry matter report is often more accurate as it reports nutrients after the moisture is removed and will be more indicative of levels within the hay after it has cured out. Often, hay marketed towards the average horse owner will go untested—horse people tend to base their opinion of hay quality on aesthetics like color, smell, and perceived palatability for their horses. Regardless, knowing how to navigate a hay analysis and understand what it means for your animals is a useful skill, especially when feeding horses with specific dietary needs or metabolic issues.
When looking at horse hay, moisture level is one of the biggest considerations. Hay that was baled with too high a moisture content will mold, which can have serious health effects on horses that ingest it. Cows, on the other hand, are much less sensitive to mold. Moisture is perhaps the biggest indicator on whether hay is marketed towards horses or cows—if it was baled at over 15% moisture or was rained on in the stack, most farmers or brokers will sell it as cow-grade hay. Optimal moisture levels are from 10-15%. A reading between 16-25% is likely to mold without a preservative, and anything over 25% will most likely have significant heat damage and be a fire hazard. Hay that has been overly dried to under 10% moisture will likely be sun-bleached, brittle, and have poor leaf retention.
Crude protein is the next consideration on a hay nutrition analysis, and it will vary greatly based on type of hay. Protein content is the main reason alfalfa is considered a premium hay for a variety of animals—its high protein level contributes to muscle development, growth, and milk production in broodmares and dairy cows. It also contains a better balance of amino acids along with its crude protein content than protein-dense grain concentrates. Legume hay like alfalfa can range from 15% to over 20% crude protein levels; grass hays generally contain 8-14%. While legumes contain more protein and calcium than grass hays, they are often very similar in megacalories per pound and phosphorus levels.
Most adult horses can be maintained at a diet of 10% crude protein, while lactating mares, horses in heavy work, or seniors might need a richer diet upwards of 15-20%. As with any nutritional choices, specifics of your animals’ health and lifestyles should be considered with a veterinarian; this framework may not be accurate for all animals. Measuring protein intake for cows is a much finer art because protein levels directly influence the amount of milk a dairy cow produces and hence must be monitored strictly. Beef cows, too, ideally consume a high-protein diet and take up much of the market of alfalfa that tests very high in protein (20-25%).
ADF (acid detergent fiber)
Acid detergent fiber (ADF) measures the level of poorly digestive components in a hay sample. As a general rule of thumb, a value of less than 45% is acceptable for horses. Coastal bermudagrass hay will often test higher than this (and also higher in neutral detergent fiber) if it was harvested after three weeks, making it a riskier option for horse hay due to the correlation between high ADF and colic. ADF connects with total digestible nutrients, or TDN, which measures the energy value of a forage. This number is most important for dairy cows, which need a diet of at least 60% TDN. A low-quality hay will range from mid-40s to low-50s in percentage, while a high-quality hay ranges from mid-50s to upwards of 60%.
NDF (neutral detergent fiber)
Neutral detergent fiber measures insoluble fiber in hay. NDF negatively correlates with amount of hay horses will eat—the higher the NDF, the less horses will eat. Hay that tests below 40% is considered excellent, and below 65% is acceptable for horses. Any higher, and horses will likely not eat it.
RFV (relative feed value)
One of the most important measures for cow-grade hay is the relative feed value, or RFV. Along with protein percentage, this number is the deciding factor for most cattlemen. An RFV of 100 is average across all types of hay, but most dairies and feed lots look for an RFV of 170 or higher. ADF and NDF are used to calculate the RFV, and because alfalfa contains less fiber than grass hay, alfalfa will generally have a much higher RFV. The Hay Market Task Force of American Forage and Grassland Council for Hay marks an RFV of above 151 as “prime” forage. While there’s no clear line between horse-quality and cow-quality hay in RFV—in fact, most dairy farmers demand higher RFVs than horse owners—both parties may look at this number as a measurement for the value, quality, and digestibility of the hay they’re buying.
DE (horse digestible energy)
The rest of the readings you may find on your hay analysis are more similar to what we’re familiar with on nutrition labels for human food. Horse digestible energy, or DE, measures megacalories in hay—according to the University of Minnesota Extension article Understanding your Hay Analysis, “a horse in light work needs 20 MCal of DE daily,” and “most hays range from 0.76 to 1.1 MCal per pound of DE.”
Ca and P (calcium and phosphorus)
Calcium and phosphorus are minerals found in hay and concentrated feed, and while nutritional needs vary for individual horses, most adult horses should have a calcium to phosphorus ratio of between 3:1 and 1:1.
Fat, while it may show up on a nutrition analysis, is very low in most forages.
Starches are something to keep an eye on for horses with metabolic issues, and while some forages tend to be lower in starch (like coastal Bermudagrass), testing is needed to determine starch levels because they vary with maturity at the time of cutting and how long the hay spent drying in the field.
ESC (ethanol-soluble carbohydrates)
The next category on a hay analysis, ethanol-soluble carbohydrates (ESC), are often referred to as sugar in forage labs as they include only analysis of the simple sugars in hay.
WSC (water-soluble carbohydrates)
Water-soluble carbohydrates, or WSC, include fructans, which are digested in the hindgut as opposed to simple sugars’ digestion in the small intestine. Because overconsumption of fructans have been linked to the onset of laminitis, this number can also be a significant one to look at for people with metabolic horses.
NSC (nonstructural carbohydrates)
Nonstructural carbohydrates (NSCs) calculate the starch plus WSC and will indicate the levels at which hay becomes unsafe for horses with sensitivities to starches and sugars—hay that tests above 10% NSC should either be soaked beforehand or not fed at all to horses with metabolic issues.
While much of the horse hay on the market goes untested, understanding how to break down the components of a test and know what it means for your horses’ nutrition is a valuable skill, especially for those whose horses may have specialized health needs. Although most horse people judge hay at least somewhat on sensory qualities like color, smell, and softness, ultimately a hay analysis done at a lab will provide better insight into which hay has the best nutritional value for your horses.
Haley Ruffner is a Sales Broker for Aden Brook and an accomplished writer on the topic of horses.
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