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You have just received a hay analysis report. The page is covered in abbreviations, percentages, and decimal figures across two columns, and none of it makes immediate sense. If that experience sounds familiar, you are not alone. Most horse owners find themselves in exactly this position, trusting a supplier's word rather than the data in front of them.
Understanding hay analysis for horses is one of the most practical skills an owner can develop. Behind those numbers lies everything that matters: how digestible the forage actually is, how much sugar and starch your horse will consume, whether the protein is genuinely usable, and whether the moisture level makes the bale safe to store. These are objective facts, not sales claims.
This tutorial walks you through every key metric on a standard report, from moisture content and fibre fractions through to crude protein, NSC values, and the calcium-to-phosphorus ratio. Sainfoin hay is used throughout as a worked benchmark, giving you real-world figures to compare against. By the end, you will have a clear priority checklist and the confidence to evaluate any hay purchase on its actual nutritional merit.
Every hay analysis report contains two columns: As Sampled and Dry Matter. As Sampled reflects nutrients measured in the hay's natural state, moisture included. Dry Matter recalculates those same nutrients after water is removed. University of Minnesota Extension identifies misreading these two columns as the most common error in owner-led hay evaluation.
The problem is that moisture content varies between bales, cuttings, and suppliers. A hay baled at 12% moisture and another at 18% will show different As Sampled nutrient figures even if their actual nutritional content is identical. Dry Matter values remove that variable, making them the only valid basis for comparing two hay sources side by side.
The difference is measurable, not trivial. A hay reporting 10% crude protein As Sampled at 15% moisture converts to roughly 11.8% crude protein on a Dry Matter basis. That gap matters when you are assessing whether a hay meets protein requirements for your horse.
The practical rule is straightforward:
Dry Matter column: use for all nutritional assessments, including fiber fractions, protein, energy, and minerals
As Sampled column: use only to confirm the moisture percentage itself
Every number discussed in the sections that follow assumes Dry Matter basis unless explicitly stated otherwise.
That one column is where moisture lives, and it needs to pass before anything else matters.
According to University of Minnesota Extension and the Iowa VMA 2023 guidelines, optimal horse hay moisture sits between 10 and 15%. This range preserves palatability, prevents storage deterioration, and keeps nutrient values stable from bale to barn.
Outside that window, problems compound in both directions:
Below 10%: Hay may become overly dry, which can affect palatability and dust levels.
Above 17%: Mold risk during storage increases materially. At or above 25%, significant quality degradation is possible; consult your supplier or agronomist on storage safety.
Moisture is a quality gate, not a performance metric. Mold activity and heat damage alter protein, fiber, and energy values, meaning the figures you are evaluating no longer reflect what your horse is actually consuming. If this number falls outside the acceptable range, the rest of the report loses reliability.
When buying hay without a lab report, ask the supplier for a certified moisture meter reading or perform a squeeze test on a core sample yourself. Owners evaluating premium legumes such as sainfoin hay should expect suppliers to provide this figure without hesitation.
Once moisture clears as a quality gate, the next two numbers tell you how much energy your horse can actually extract from the hay and how much of it they'll willingly eat.
Acid Detergent Fiber (ADF) measures cellulose and lignin, the least digestible fractions of plant material. As ADF rises, digestibility and available energy fall proportionally. According to Iowa VMA 2023, ADF values of 30 to 35% (dry matter basis) indicate readily digestible hay suited to horses in work, growing horses, and lactating mares. Values above 45% signal low-energy forage appropriate for horses that need restricted calorie intake.
Neutral Detergent Fiber (NDF) measures total insoluble fiber: hemicellulose, cellulose, and lignin combined. Its primary role is predicting voluntary intake. The higher the NDF, the less hay a horse will physically consume per day. Optimal NDF sits between 40 and 50%; above 65%, most horses will eat it reluctantly. Very high-NDF hay can serve a useful purpose as slow or occupancy forage for horses on calorie restriction.
NDF is always higher than ADF. The difference between them represents hemicellulose, a moderately digestible fraction that feeds hindgut fermentation. A wider gap means more fermentable fiber available to the gut microbiome.
Practical targets by horse type:
Performance horses: ADF below 35%, NDF below 50%
Easy keepers or metabolically sensitive horses: For horses needing calorie control, higher ADF/NDF hays naturally limit energy intake without strict rationing
Crude protein tells you whether the hay can support tissue repair, muscle development, and basic metabolic function.
CP is calculated by measuring total nitrogen in the hay and multiplying by 6.25. That formula captures quantity, not quality. By forage type, on a dry matter basis, Iowa VMA 2023 benchmarks are: grass hays 8 to 14%, mixed grass-legume hays 14 to 17%, and legume hays 15% and above. For most adult horses in light to moderate work, 12% CP meets baseline requirements.
Lactating mares and foals sit well above that threshold. If you are feeding either, CP alone is an insufficient guide; consult an equine nutritionist to build the full protein picture.
The limitation every buyer needs to understand: two hays can show identical CP readings while delivering very different amounts of usable amino acids. CP says nothing about how much protein actually reaches the small intestine for absorption.
Sainfoin Supreme, Heavenly Hay's leading forage for performance horses, tests firmly in the legume CP tier, the standard report will show the exact figure. What it will not show is the digestibility advantage that comes alongside it.
The carbohydrate load in hay is a separate concern from protein quantity, and for metabolically sensitive horses it is the more urgent one.
Non-Structural Carbohydrates (NSC) represent the combined sugar and starch fraction that drives insulin response. For horses with insulin dysregulation, equine metabolic syndrome, or a laminitis history, NSC is the single most critical number on any report.
NSC is not always listed directly. Calculate it yourself using:
NSC = Water-Soluble Carbohydrates (WSC) + Starch
If your report shows Ethanol-Soluble Carbohydrates (ESC) rather than WSC, substitute ESC + Starch for the most clinically relevant estimate.
The widely referenced safety threshold is NSC at or below 10 to 12% on a dry matter basis (Oregon State University Extension). Hay above this level carries meaningful laminitis risk for susceptible horses.
Non-Fiber Carbohydrates (NFC) is a broader figure: NFC = 100 minus (moisture + crude protein + ADF + ash). It includes fermentable sugars but is less precise than a direct WSC or ESC measurement. Use it as a cross-check, not a replacement for NSC when managing metabolic horses.
First-cut timothy harvested under stress can carry elevated NSC; testing individual batches is essential, as type averages are unreliable.
Sainfoin hay typically falls at the lower end of the NSC spectrum, making it a naturally suitable low-sugar option, request lab documentation from your supplier to confirm the specific batch figure. For guidance on applying these numbers to your horse's specific needs, meet our equine nutrition expert.
Digestible Energy (DE) is the standard energy metric in modern equine nutrition, expressed in megacalories per pound (Mcal/lb) on a dry matter basis. Quality horse hays typically fall between 0.76 and 0.94 Mcal/lb (Iowa VMA 2023). A light working horse needs approximately 20 Mcal per day, so knowing your hay's DE value lets you calculate whether forage alone covers that requirement or whether concentrate must fill the gap.
Total Digestible Nutrients (TDN) is an older expression of the same concept, ranging from 40 to 55% in horse hays. It appears on many laboratory reports and can be used interchangeably with DE for general comparisons, but DE is the preferred metric in current practice.
Both figures matter most for horses in active work, recovery, growth, or late gestation. For a mature horse in light maintenance, they are useful context rather than the primary purchasing criterion.
The most common error is defaulting to the highest-DE hay regardless of actual workload. For easy keepers or lightly worked horses, excess dietary energy contributes directly to weight gain and metabolic stress. The correct approach is matching DE to demonstrated energy demand, not maximizing it. The Heavenly Hay approach to premium forage reflects this principle: quality means the right nutrient profile for the horse, not simply the highest numbers on the report.
Shift attention next to the mineral panel, specifically the calcium-to-phosphorus (Ca:P) ratio, the single most important mineral figure on the report.
For adult maintenance horses, the acceptable Ca:P range is 1:1 to 3:1 on a dry matter basis (Iowa VMA 2023). When phosphorus exceeds calcium, the body cannot absorb calcium normally. The skeleton compensates by releasing stored calcium, leading over time to nutritional secondary hyperparathyroidism. Even short-term inversion carries meaningful risk in growing horses.
Legume forages, including sainfoin, naturally carry calcium at roughly six times their phosphorus level, supporting a healthy ratio. This is one reason Sainfoin Supreme, our leading forage solution for performance horses suits horses that also receive grain. Cereal grains are low in calcium and high in phosphorus; adding them to a legume-based diet can shift the ratio, so overall mineral balance should be assessed when grain is part of the program.
Grass-dominant hays grown on phosphorus-rich soils occasionally present borderline ratios. A lab analysis is the only reliable way to identify this risk before it becomes a feeding problem.
Beyond Ca:P, magnesium and potassium are worth reviewing for horses with a history of muscle issues or in regions with known soil imbalances. Most standard reports include both; interpretation is best done with a veterinarian or equine nutritionist.
Minerals tell you whether a hay is safe to feed consistently. Condensed tannins tell you something different: how much of the protein in that hay your horse will actually use.
This metric is not present on most standard reports; confirm availability with your chosen forage testing laboratory before submitting your sample.
What condensed tannins do: Research in ruminants shows these compounds form stable complexes with dietary proteins, shielding them from microbial breakdown, a mechanism that is also consistent with observed outcomes in horses. More intact protein reaches the small intestine for absorption as usable amino acids. A hay with condensed tannins can therefore deliver meaningfully more functional protein than its CP number suggests. Research also documents reduced gas production, suppression of harmful microbial populations, and a potential reduction in internal parasite burden (demonstrated in ruminant studies; equine-specific data is emerging), which is why sainfoin has attracted growing interest as a functional forage rather than just a feed ingredient.
Sainfoin's natural advantage: Sainfoin is one of very few commercially available hays with condensed tannins at biologically active levels, request proanthocyanidin quantification from your forage lab to confirm the specific concentration in any batch. Most grass and legume hays contain none. You can find more detail in the Heavenly Hay FAQ.
How to request the test: Ask your laboratory for "condensed tannin" or "proanthocyanidin" quantification. Confirm availability before submitting your sample, as not all equine forage labs offer this panel.
Two hays can share an identical CP reading and produce very different outcomes in topline development, digestive comfort, and overall condition. Condensed tannin data is the only objective way to see that difference.
With every metric covered in this guide, here is your single-reference summary. Use this checklist each time you open a new hay analysis report.
Metric |
Basis |
Target Range |
Red Flag |
|---|---|---|---|
Moisture |
As sampled |
10–15% |
Below 10% (palatability and dust concerns); above 17% (mold risk) |
ADF |
Dry matter |
30–35% (performance horses) |
Above 45% (low energy only) |
NDF |
Dry matter |
40–50% |
Above 65% (limits voluntary intake) |
Crude Protein |
Dry matter |
12% baseline; 14–17% mixed; 15%+ legumes |
Always pair with digestibility context |
NSC |
Dry matter |
At or below 10–12% for metabolically sensitive horses |
Above 12% for horses with insulin dysregulation or laminitis history |
Digestible Energy |
Dry matter |
0.76–0.94 Mcal/lb |
Mismatch to actual workload |
Ca:P Ratio |
Dry matter |
3:1 to 1:1 |
Below 1:1; consult a veterinarian immediately |
Condensed Tannins |
Dry matter |
Varies by batch; request proanthocyanidin panel |
Not on standard reports; confirm lab availability before submitting sample |
A few points worth reinforcing:
NSC is the priority threshold for any horse with metabolic concerns. Calculate as WSC + Starch (or ESC + Starch) if not directly reported.
Ca:P below 1:1 is not a "monitor and reassess" result; it requires immediate veterinary input.
Absence of a condensed tannin value means the test was not run, not that tannins are absent. For sainfoin, request this panel explicitly. Sainfoin Supreme, Heavenly Hay's leading forage for performance horses, includes full analysis documentation so you can verify every number on this checklist directly.
With the priority framework now complete, apply it in sequence every time you open a report. Start with moisture, then NSC, then ADF/NDF, then CP, then DE/TDN, then Ca:P.
Never accept a supplier's verbal description as a substitute for documented numbers. A current analysis from a certified forage testing laboratory is the only objective basis for any hay purchase decision.
Heavenly Hay provides full analysis reports for its sainfoin hay, including condensed tannin data on request. Applying this framework directly to those figures is the most practical next step for any owner considering a switch.
Finally, hay evaluation compounds with practice. Each report you read sharpens your reference frame. Over time, you will recognise genuinely good forage on paper before a single bale reaches your yard. That fluency is worth building, and every report is a step toward it.
Reading a hay analysis report is a skill that pays dividends with every purchase. The key principles are straightforward: always work from dry matter values, prioritise NSC for metabolically sensitive horses, use ADF and NDF to gauge digestibility, and verify your Ca:P ratio before committing to a supply. For premium forages like sainfoin, condensed tannin data adds a layer of insight that standard panels simply cannot provide.
The checklist in this guide gives you a repeatable system, not a one-time reference. Use it consistently and your confidence will grow with each report you review.
Your next step is practical: request a full analysis from your current or prospective hay supplier and work through the numbers in sequence. If you are considering sainfoin, explore Heavenly Hay's fully documented forage range and put this framework to work immediately.
