Two alfalfa lots can have similar protein levels but different fiber digestibility, intake potential and delivered costs. Compare the lab results with the condition of the delivered hay and the needs of the cows that will eat it.
To assess hay quality, start by checking the condition and identity of the delivered lot. Then read the laboratory report on a consistent dry-matter basis, comparing crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), fiber digestibility (NDFD), and relative forage quality (RFQ). Finally, consider price, feed safety, and the requirements of the group that will actually eat the hay.
A higher RFQ is useful when comparing similar forages, but it does not guarantee more milk or justify any purchase price. The best-value hay is the lot that helps your nutritionist build an appropriate ration at a sustainable cost.
Can You Judge Hay Quality by Color, Smell, and Touch?
A visual inspection is a good first screen at delivery, especially for moisture damage, contamination, and differences between bales. But it cannot replace a nutrient analysis.
Color and leaf content. Green hay can be a positive sign of careful harvesting, but sun-bleached hay is not automatically poor-quality feed. A bright exterior also does not prove that the bale's center has acceptable moisture or nutrient composition. Compare the leaf-to-stem balance, maturity, foreign material, and condition of the bale interior rather than buying by color alone. Leaf loss during handling is particularly important when evaluating alfalfa.
Smell. A normal hay aroma is reassuring, while musty, moldy, or scorched odors deserve attention. A caramel-like smell may suggest heating during storage and possible heat damage. Odor is a warning signal, not a laboratory measurement.
Moisture and temperature. A bale that feels damp, unusually warm, clumped, or spoiled should be kept out of normal feed inventory pending evaluation. Feeling or bending stems cannot accurately establish moisture percentage. Use a suitable hay moisture meter and investigate inconsistent readings. Do not open or move a stack that may be dangerously overheated or smoldering; follow fire-safety procedures.
| Field observation | What it can tell you | What it cannot tell you |
|---|---|---|
| Green color and good leaf retention | Possible good harvesting and handling | Exact CP, NDF, or RFQ |
| Coarse stems and advanced maturity | Possible increase in structural fiber | Actual fiber digestibility without testing |
| Musty odor or visible mold | Reason to isolate and investigate the lot | Type or concentration of mycotoxins |
| Dampness or abnormal heating | Possible storage and safety problem | Precise dry-matter percentage |
| Clean, dry-looking bales | No obvious defect at the inspected location | That every bale in the lot is safe or nutritionally equal |
The receiving decision and the ration decision are different. Physical inspection helps identify feed that should be questioned or rejected. Laboratory analysis helps determine the nutritional value of an acceptable lot.
Which Numbers Matter on a Dairy Hay Test Report?
Hay test reports contain several measurements, but not all answer the same question. Before comparing any values, confirm the forage type, lot number, sampling date, laboratory method, and whether results are stated as-fed or on a dry-matter (DM) basis.
| Indicator | What it represents | How a dairy farm uses it |
|---|---|---|
| DM — Dry Matter | Feed remaining after water is removed | Calculates actual nutrient delivery and cost per unit of dry feed |
| CP — Crude Protein | Estimate of total nitrogen expressed as protein | Assesses protein contribution; does not describe protein availability by itself |
| NDF — Neutral Detergent Fiber | Main structural cell-wall fiber fraction | Helps evaluate rumen fill and potential intake constraints |
| ADF — Acid Detergent Fiber | Less digestible fiber fraction, including cellulose and lignin | A general indicator related to forage maturity and digestibility |
| NDFD — NDF Digestibility | Proportion of NDF digested under a specified laboratory test | Differentiates forages with similar NDF but different digestible fiber |
| RFV — Relative Feed Value | Index estimated primarily from ADF and NDF | Traditional forage ranking; does not directly measure fiber digestibility |
| RFQ — Relative Forage Quality | Index using estimates of dry matter intake and energy, including digestible fiber | Compares forage lots and helps allocate feed to animal groups |
| Ash | Total mineral residue, including naturally occurring minerals and possible soil contamination | Helps investigate excessive soil or dirt contamination |
Some reports also include total digestible nutrients (TDN), net energy of lactation (NEL), nonfiber carbohydrates, minerals, and other values. Select the test package according to the ration and purchasing decision, rather than ordering every available assay for every bale.
First, Check the Reporting Basis
A report might show CP as 18% of dry matter, while another shows protein as a percentage of the feed as delivered. These figures cannot be compared directly.
For example, hay containing 90% dry matter and 18% CP on a DM basis contains:
0.90 × 18% = 16.2% CP on an as-fed basis.
The protein itself has not changed. Only the reporting basis has changed. For a fair comparison, place forage nutrient analyses on the same DM basis before evaluating the lots.
What Do NDF, ADF, and NDFD Really Mean?
These three indicators describe different aspects of fiber. The most useful interpretation comes from reading them together.
NDF: How Much Structural Fiber Is Present?
NDF includes much of the forage's cell-wall material. A higher NDF concentration generally means more physical fill in the rumen and may limit how much forage an animal can consume.
But lower NDF is not automatically better for the complete ration. Dairy cows still require enough effective fiber to support normal chewing and rumen function. Particle length, digestibility, and the other ingredients in the TMR matter as well.
ADF: A Clue About Digestibility, Not a Direct Measurement
ADF represents a less digestible portion of the plant's structural fiber. As many forages mature, ADF tends to increase and digestibility often declines.
However, ADF is an indirect predictor. Two hays with similar ADF may still have different actual digestibility. That is one reason modern forage evaluation looks beyond ADF alone.
The University of Nebraska–Lincoln's guide to ADF and NDF explains the distinction between these measurements.
NDFD: How Digestible Is the Fiber?
NDFD measures the digestibility of the NDF fraction under stated laboratory conditions. It adds useful information when two alfalfa samples contain similar amounts of fiber but that fiber behaves differently during digestion.
Always check the incubation time and testing method. An NDFD result measured after 30 hours should not be compared as though it were identical to a 48-hour result. When comparing suppliers, request consistent methods or have the samples analyzed by the same laboratory. The University of Wisconsin's explanation of NDF digestibility describes why these differences matter.
RFV vs. RFQ: Which Index Should You Use?
RFV and RFQ are both relative forage-ranking tools. Neither is a promise of milk production.
RFV (Relative Feed Value) uses NDF to estimate intake potential and ADF to estimate digestibility. Its limitation is that it assumes a relatively fixed relationship between ADF and digestibility.
RFQ (Relative Forage Quality) was developed to improve the comparison by incorporating estimates of digestible fiber into intake and energy calculations. This can be especially valuable when the digestibility of fiber differs from what ADF alone would suggest.
According to the University of Wisconsin's RFQ guidance, RFQ is useful for buying, selling, ranking, and allocating forage to animal groups. It does not translate directly into a particular number of liters of milk.
Remember these distinctions:
- NDF: How much structural fiber is in the forage?
- ADF: What does the less digestible fiber fraction suggest about potential digestibility?
- NDFD: How digestible was the fiber under the laboratory's test conditions?
- RFQ: How does the forage rank as a combined estimate of intake and energy potential?
For an actual dairy ration, your nutritionist will still need the individual nutrient and energy values, not just one RFQ score. RFQ formulas may also differ according to forage type and laboratory calculation method, so check the method before using values from different reports interchangeably.
Example: Which of Two Alfalfa Lots Is the Better Purchase?
Consider two hypothetical alfalfa deliveries being evaluated for a dairy farm. The figures below are illustrative report values, not tests of actual supplier hay. RFQ values are shown as if reported by the same laboratory; they cannot be recalculated from only the selected measurements in this table.
| Measurement | Lot A | Lot B |
|---|---|---|
| Dry matter, as delivered | 88% | 90% |
| CP, % DM | 20.0% | 18.5% |
| NDF, % DM | 37% | 41% |
| ADF, % DM | 28% | 32% |
| NDFD, 48-hour test (% of NDF) | 51% | 46% |
| RFQ, illustrative lab result | 185 | 150 |
| Delivered price, USD per metric ton as-fed | $320 | $290 |
| Price, USD per metric ton DM | $363.64 | $322.22 |
The dry-matter price is calculated as:
Price per metric ton of DM = delivered price per metric ton as-fed ÷ dry-matter fraction.
For Lot A: $320 ÷ 0.88 = $363.64 per metric ton DM.
For Lot B: $290 ÷ 0.90 = $322.22 per metric ton DM.
Lot A has stronger reported fiber and protein indicators, but its dry matter costs about 13% more than Lot B's. Is the premium justified?
That depends on what the herd needs. If Lot A helps meet intake and energy needs in a high-producing group, the higher price may be reasonable. If Lot B can support the required ration with an economical balance of other ingredients, Lot B could be the better purchase. Neither result can be established from RFQ alone.
Ask three practical questions before choosing:
- Which nutrients are limiting in the current ration? The value of extra protein is different from the value of improved digestible fiber.
- How much will the complete ration cost? Compare the forage's contribution alongside concentrates and other feeds, not only the forage invoice.
- Can the supplier consistently deliver the same quality? Repeated lot changes may require extra testing, ration adjustments, and tighter inventory control.
A simple price-per-RFQ-point calculation may help screen market offers, but it is not a physical unit of digestible nutrients and should not replace ration-level costing.
Is the Highest-RFQ Hay Right for Every Group?
No. Different animal groups require different nutrient densities, and feeding the most expensive alfalfa to every group may create unnecessary cost or nutritional imbalance.
| Animal group | General allocation principle | Additional consideration |
|---|---|---|
| High-producing lactating cows | Reserve suitable, highly digestible forage where its nutrient contribution offers the greatest value | Check actual intake, effective fiber, and the complete ration |
| Fresh cows | Prioritize consistent, palatable, appropriately formulated forage | Manage transition health and intake; avoid abrupt changes |
| Mid- or lower-producing cows | Match forage quality to production and body condition rather than automatically selecting the highest RFQ | Evaluate whole-ration cost and nutrient balance |
| Growing heifers | Supply clean forage that supports target growth without excess energy | Balance by age, size, and desired growth rate |
| Dry and pre-fresh cows | Choose forage according to the stage-specific ration, not RFQ alone | Potassium and dietary cation–anion balance (DCAD) are particularly important before calving |
A high-quality alfalfa lot may be valuable to a lactating group but less appropriate in a pre-fresh ration if its mineral composition makes the required DCAD balance difficult. The University of Wisconsin's dry-cow nutrition guidance explains why forage mineral testing matters in this period.
Match identified forage lots to each group's ration, production stage and nutrient requirements.
What If the Supplier's Hay Report Does Not Match the Delivery?
A laboratory certificate describes the sample that was tested. It does not automatically prove that every bale, container, or subsequent shipment has identical quality.
This is particularly important with imported or recompressed alfalfa. Different cuttings, packing dates, storage conditions, and transport exposure can create differences between deliveries.
When a delivery and its certificate disagree, review the issue in this order:
- Match the records: Check forage type, harvest or processing lot, supplier, certificate date, container or truck number, and warehouse position.
- Match the testing basis: Compare CP, NDF, ADF, and other results on the same DM basis, noting laboratory methods and any NDFD incubation time.
- Inspect across the load: Look beyond the first bale, including exposed upper and lower positions and representative bale interiors where safe.
- Take representative lot samples: Use a suitable hay corer and a sampling plan agreed with the laboratory. Keep separate lots separate, preserve leaves and fine material, and record sample identity. For routine testing, Alabama Cooperative Extension describes collecting 15–20 cores per defined lot.
- Resolve the difference before changing the ration: If results remain materially different, involve the nutritionist, laboratory, and supplier. Keep suspect or damaged forage separate until a suitable decision is made.
For a full step-by-step procedure, see NexAgri's guide to sampling stored forage, silage, and TMR.
What About Ash and Mold Risk?
Ash includes natural plant minerals as well as potential contamination from soil or sand. An unexpectedly high result deserves investigation, but a single ash percentage does not prove how much is dirt: forage species, mineral uptake, and growing conditions affect the baseline. The University of Wisconsin's ash guidance explains why ash should be interpreted in context.
Visible mold, musty odor, excessive moisture, and abnormal heating are feed-acceptance and safety concerns, not merely reasons to discount the price. Separate affected material and assess the lot. A routine CP/NDF/RFQ report does not certify the absence of mycotoxins, and mixing questionable forage into TMR is not a reliable safety solution.
How Do You Turn a Hay Test into a Better TMR Ration?
A forage report becomes useful only when the correct numbers reach the ration formulation and the feed actually delivered to cows.
A practical sequence is:
Verify the forage lot → update the ingredient analysis → have the ration reviewed → convert dry-matter targets into as-fed loading weights → mix and deliver consistently → check intake and refusals.
Example: Why a Dry-Matter Change Alters Mixer Loading
Suppose a ration calls for 9 kg of dry matter from one forage ingredient per cow.
- At 90% DM, the required as-fed amount is 9 ÷ 0.90 = 10.00 kg.
- At 85% DM, the required as-fed amount becomes 9 ÷ 0.85 = 10.59 kg.
If the farm continues loading only 10 kg after that moisture change, it supplies 8.5 kg DM rather than the intended 9 kg. This example shows only the weight conversion; a nutritionist still needs to assess any other changes in forage composition or ration safety before adjusting the formula.
On a commercial dairy, ingredient records should identify the lot and the analysis used. The feeding team can then check load-cell calibration, loading order, mixer operating conditions, batch size, feed distribution, and the actual ration available at the bunk.
NexAgri supplies TMR mixers and feed preparation systems for dairy operations. A suitable mixer and weighing system can help operators execute an approved formula more consistently, but mixing cannot improve poor forage quality or correct an inaccurate laboratory sample. Reliable feeding still depends on verified ingredients, correct batch weights, equipment maintenance, and routine observation of the herd.
Dairy Hay Purchasing Checklist
Before accepting or allocating a new hay lot, confirm the following:
- The supplier's certificate matches the delivered lot and forage type.
- Nutrient figures use a clearly stated reporting basis, preferably DM for comparisons.
- CP, NDF, ADF, and any NDFD or RFQ results have appropriate laboratory methods.
- Unusual ash values, moisture, dirt, odor, or damaged bales have been investigated.
- Representative samples and batch records are available when needed.
- Delivered prices have been compared per unit of dry matter, not just per wet ton.
- The nutritionist has considered which animal group can use the forage most effectively.
- Any updated loading weights have been communicated to the TMR operator.
- Storage and feeding records keep different lots traceable.
Frequently Asked Questions
Is green hay always better than yellow hay?
No. Green color can be useful during inspection, but sunlight, maturity, handling, and storage all affect appearance. A nutrient test provides the stronger basis for comparing acceptable forage lots.
Is lower NDF always better for dairy cows?
Not necessarily. Lower NDF in a comparable forage may indicate less rumen fill and greater potential intake, but the complete dairy ration still needs enough effective fiber. Digestibility and particle size matter too.
Does a higher RFQ mean more milk per cow?
No. RFQ ranks forage based on estimated intake and energy potential. Actual milk production depends on the complete ration, cow health, stage of lactation, environment, and management.
What is the difference between RFV and RFQ?
RFV relies mainly on ADF and NDF estimates. RFQ incorporates digestible fiber into its estimates of intake and energy, so it can better distinguish some forages that have similar conventional fiber measurements.
Why can two alfalfa lots with similar protein have different feeding values?
They may differ in NDF, ADF, fiber digestibility, ash, minerals, or moisture. Protein percentage alone cannot describe digestible energy, physical fiber, or economic value.
Can I compare NDFD results from different laboratories?
Check the methods first, especially whether results were measured after the same incubation time. If the methods differ, a direct numerical comparison may be misleading.
How often should a dairy test purchased hay?
A new lot or a meaningful quality change warrants a new, representative assessment. The frequency of further testing depends on the volume purchased, supplier consistency, risk, and how quickly the forage is used. Coordinate a practical schedule with your laboratory and nutritionist.
Conclusion
Good dairy hay buying starts with clean, traceable feed and ends with a ration that delivers the nutrients cows actually need. Appearance and moisture checks help screen incoming bales. CP, NDF, ADF, NDFD, and RFQ help explain nutritional differences. Dry-matter pricing and ration analysis help decide whether the higher-scoring lot is worth the premium.
Keep purchased lots identifiable, verify the laboratory method and compare prices on a dry-matter basis. Give updated forage results to the nutritionist and mixer operator so the ration and loading sheet reflect the hay being fed.
