Why the Full Report Matters — Not Just the RFV
Relative Feed Value (RFV) is the number most hay producers and hay buyers use as a shorthand for quality. It is a useful single-number index — but it is derived from only two of the many parameters on the forage report (ADF and NDF), and it captures only the energy and digestibility dimension of hay quality. It says nothing about protein levels, buffering capacity, mineral content, moisture safety, or contamination from soil pickup — all of which matter to the buyer and to the animals the hay feeds.
More importantly for the producer: the individual parameters on the report tell you specifically what went right and what went wrong in your production system. A CP reading of 16% and an RFV of 140 tells you something useful. A CP of 20% and an RFV of 140 on the same hay tells you something completely different — the higher protein at the same RFV likely indicates you cut slightly earlier and had more leaf, while the same RFV means fiber maturity was equivalent. Understanding that distinction guides your next cutting decision.
Moisture and Dry Matter: The Foundation of All Other Values
Moisture and dry matter (DM) are always the first values on the report for a reason: every other parameter is expressed on a dry matter basis, which means the moisture percentage determines what those values mean in terms of weight delivered to the buyer. High moisture makes all other values appear better on a per-pound-as-fed basis than they actually are per pound of DM delivered.
The water content of the hay as sampled. Round bale hay at 10–15% is in the safe storage range — below the threshold where mold activity is significant. Above 18%: heating and mold risk. Above 22%: severe heating risk with potential fire hazard in stacks.
The fraction of each pound of hay that is actual dry feed rather than water. A 1,050-lb bale at 87% DM delivers 913 lbs of dry feed. The same bale at 80% DM (a bale baled slightly wet) delivers only 840 lbs. Buyers who pay per ton are effectively paying for 73 lbs more water in the wetter bale — understanding this matters when comparing prices from different sources.
Crude Protein: What It Tells You and What It Does Not
Crude protein (CP) is the most widely understood forage parameter and the one most directly affected by your production decisions. It measures total nitrogen in the sample multiplied by 6.25 (the nitrogen-to-protein conversion factor), and it tells you how much of the hay’s dry matter is proteinaceous — relevant to both ruminant requirements and to hay market pricing.
| CP Range (DM basis) | What it indicates | Primary causes if below expectation |
|---|---|---|
| 20%+ (alfalfa) | Excellent — pre-bud or bud stage cut with high leaf retention; superior for dairy and horse premium markets | N/A — this is target quality |
| 17–20% (alfalfa) | Good — early bloom cut with good leaf content; suitable for most dairy and beef supplement uses | Cutting slightly past bud stage; minor leaf loss at raking |
| 14–17% (alfalfa) | Fair — mid-bloom or later cut; suitable for beef supplemental, horse maintenance | Cutting at 25–50% bloom; significant leaf loss; or poor stand with high stem-to-leaf ratio |
| <14% (alfalfa) | Poor — late cut or heavy leaf loss; limited market beyond bedding or cow roughage supplement | Late cutting (full bloom to seed set); rain damage causing leaching of soluble protein; excessive rake shatter |
The key limitation of CP: it measures total nitrogen, not protein availability. Hay that overheated during baling (above 150°F) converts soluble protein to heat-damaged protein (ADIN — acid detergent insoluble nitrogen) that passes through the rumen as feces rather than being absorbed. A CP of 18% in overheated hay may deliver only 13–14% available protein. The ADIN or ADICP fraction on the report (if tested) reveals this damage — values above 15% of total CP indicate significant heat damage.
ADF and NDF: The Fiber Pair That Drives RFV
Acid Detergent Fiber (ADF) and Neutral Detergent Fiber (NDF) are the two fiber fractions that together determine the hay’s digestibility and intake potential — and therefore its RFV and energy values. They are both measures of what the plant cell wall contains, but they measure different cell wall components.
What it measures: The structural, indigestible cell wall fractions. ADF is inversely related to digestibility — higher ADF means less energy is extracted from each pound of hay. ADF is the single strongest predictor of hay energy content.
Typical ranges (alfalfa, DM basis):
Supreme: below 27% | Good: 27–29% | Fair: 30–32% | Poor: above 34%
What it measures: Total insoluble cell wall — all structural fiber. NDF is the primary predictor of voluntary intake: high NDF hay physically fills the rumen, limiting how much an animal can eat per day regardless of palatability. High NDF = lower intake potential.
Typical ranges (alfalfa, DM basis):
Supreme: below 34% | Good: 34–36% | Fair: 37–40% | Poor: above 42%
DMI (Dry Matter Intake, % body weight) = 120 ÷ NDF%
RFV = (DDM × DMI) ÷ 1.29
Reference: full-bloom alfalfa = RFV 100
The RFV formula shows exactly why both ADF and NDF matter: lower ADF raises DDM (more digestible energy per pound), and lower NDF raises DMI (animal can consume more pounds per day). An RFV of 160 vs. 130 reflects both higher energy density and higher intake potential — the combination that dairy nutritionists pay a premium for in supplier contracts.
Energy Values: NEl, NEm, NEg — What Each Is Used For
Net energy values — NEl (net energy for lactation), NEm (net energy for maintenance), and NEg (net energy for gain) — are calculated from ADF and represent the usable energy available to the animal after accounting for digestive losses. Different animals and different production purposes use different energy values for ration balancing, and misapplying the wrong energy value to a ration is a common source of ration formulation errors.
| Energy value | Use in ration formulation | Target range (alfalfa) | If below target, cause is… |
|---|---|---|---|
| NEl (Mcal/lb) | Dairy cow energy requirements | 0.62–0.70+ | High ADF from late cutting; rain leaching of soluble carbohydrates |
| NEm (Mcal/lb) | Beef cow maintenance; horse energy | 0.55–0.65+ | Same as NEl — all three values move together with ADF |
| NEg (Mcal/lb) | Stocker and feedlot gain calculations | 0.35–0.45+ | Significantly lower than NEm — less efficient for growth than maintenance, as expected |
Ash Content: The Soil Contamination Indicator
Ash is the incombustible mineral residue remaining after the hay sample is burned in a furnace. In clean, well-managed hay, ash represents the inherent mineral content of the plant — primarily calcium, phosphorus, potassium, and magnesium — and should fall in the 8–12% range for alfalfa on a DM basis. Values significantly above this range indicate soil contamination mixed into the bale.
High ash devalues hay in two ways: it directly displaces feed nutrients (soil ash is indigestible), and it reduces apparent protein and energy values by dilution — a bale with 18% ash has 18% of its weight as indigestible soil mineral before counting any feed components. For export markets (Japan, Korea, China) that have ash specifications of 7–10%, achieving consistent low ash requires polyurethane tines, correct pickup height on every field, and avoiding baling on wet days when soil is most likely to be picked up with the windrow. The complete guide to improving hay quality parameters including ash content is at how to improve hay quality.
How to Use the Report to Improve Next Cutting
Each parameter on the report points to a specific production decision that created it. This is the diagnostic value of systematic forage testing — not just knowing the quality, but knowing what to change. The most actionable improvements by parameter:
Cut earlier. Each 3–5 days earlier at the bud-to-early-bloom window typically adds 1.5–3 percentage points of CP in alfalfa. Also check: is leaf loss at raking removing the high-protein leaf fraction?
Cut earlier (same solution as low CP). High ADF and low CP together confirm late cutting as the cause. If only ADF is high with normal CP, suspect significant leaf loss that removed high-protein leaf while leaving high-ADF stems.
Raise pickup height immediately; check for sandy soil or wet field conditions; consider switching to polyurethane tines. Also: ensure mower cutting height is not too low (cutting too close to soil increases soil contact at mowing).
Ted earlier after cutting and/or use a more aggressive conditioning setting. Also review: is your mower-conditioner creating adequate conditioning damage to the stems? See the mower-conditioner selection guide for conditioning intensity comparison.
Market-Grade Standards: How Labs and Buyers Classify Hay
Most hay testing labs and commercial hay markets use a standardized grading system based on RFV and CP. Understanding these grades and their typical price differential helps you interpret where each load of hay falls in the market and what quality improvement is needed to move to the next grade tier.
| Grade | ADF % | NDF % | RFV | Typical premium | 主要市場 |
|---|---|---|---|---|---|
| Supreme | <27 | <34 | >185 | +$30–$60/ton over Good | High-producing dairy, show horses, export Japan/Korea |
| Premium | 27–29 | 34–36 | 170–185 | +$15–$30/ton over Good | Dairy, quality horse market |
| 良い | 29–32 | 36–40 | 150–170 | Benchmark price | Beef cows, horse maintenance, sheep |
| Fair | 32–35 | 40–44 | 130–150 | −$10–$20/ton vs Good | Dry beef cows, background cattle |
| Utility | >35 | >44 | <130 | −$20–$40+/ton vs Good | Bedding supplement, dry cows, roughage only |
Grades based on Hay Marketing Task Force quality standards (USDA Agricultural Marketing Service framework). Actual market price premiums vary by region, season, and supply conditions. ADF and NDF ranges shown for alfalfa; grass hay grades use different thresholds — consult the lab report header for the species-specific grade applied.
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