The Ultimate Guide: How Do You Properly Sample Stored Forage, Silage, and TMR for Testing?

A reliable forage test begins with a representative sample—not with the laboratory report. To sample stored forage, silage, or a total mixed ration (TMR), first identify the feed lot and the purpose of the test. Then collect several small subsamples from appropriate locations, combine them only when an average is what you need, and package the final sample according to the laboratory's instructions.

The procedure is different for silage, TMR, and baled hay. Silage should be sampled from freshly removed material at a safe location; TMR sampling depends on whether you want nutrient composition, mixing consistency, or feed-sorting information; and hay should usually be sampled with a core probe across multiple bales from the same lot.

A dairy nutritionist may formulate a ration correctly and still get an unexpected feeding result if the tested sample was collected from the wrong part of the pile—or if several different deliveries were blended into a single laboratory bag. On farms using TMR mixers, it is equally important to know whether the test represents the ration formulated, the ration delivered, or the feed the cows actually consumed.

This guide explains how to choose the correct sampling method, avoid common mistakes, and turn feed-analysis results into practical decisions for a dairy or beef operation.

Before Sampling: What Exactly Are You Trying to Test?

Do not collect a sample until you know which feed or decision it is supposed to represent. The most important first step is defining the lot and the testing objective.

Question	What the sample should represent	Recommended approach
What nutrients are in this silage?	The identified silage currently being fed	Multiple subsamples of safely removed fresh silage; composite when appropriate
Does the TMR match the formulated ration?	Freshly delivered TMR before cows sort it	Representative composite from the specified feeding batch or bunk
Is the mixer distributing feed evenly?	Differences from the beginning, middle, and end of unloading	Separate, labeled samples—do not combine them
Are cows sorting their feed?	Feed offered compared with feed remaining later	Separate fresh-TMR and refusal samples, with collection times recorded
What is the quality of purchased hay?	One clearly defined field, cutting, or delivery lot	Hay-core samples from randomly selected bales
Is contamination suspected?	The material associated with the suspected problem	A laboratory-approved sampling plan, often including separately identified suspect areas

A composite sample gives an average; it does not reveal where variation occurs. That distinction matters when a TMR mixer discharges different material at each end of a feed bunk, or when an imported alfalfa shipment contains bales affected by condensation.

Define a lot before opening the sample bag

For baled hay, a practical lot usually consists of the same forage type, field or source, cutting, and similar harvest and storage conditions. For silage, record the bunker or bag, the area or harvest section being fed, and the sampling date. For TMR, record the ration name, mixing batch, feeding group, and delivery time.

Do not mix different harvests, suppliers, wet and dry material, or suspect and unaffected areas merely to reduce laboratory fees. The resulting average can be difficult to interpret and impossible to trace back to one problem lot.

How Do You Safely Sample Corn Silage From a Bunker or Pile?

Do not walk up to a high silage face to take samples in a nine-point grid. Even a face that looks firm can collapse without warning. The safer approach is to have trained personnel use normal unloading equipment to remove fresh silage and carry it away from the face before anyone collects subsamples.

Penn State Extension's horizontal silo safety guidance specifically warns about face collapse during sampling and recommends moving feed away with a front-end loader.

A practical sampling sequence

1. Plan the sample around normal feed removal. Identify the bunker, section, and feed-out period being assessed. Keep people clear of the face and the path of moving machinery.
2. Have the operator safely remove the fresh feed. Where practical, use material from normal unloading that covers the layers or area actually entering the ration. Do not ask the operator to create an undercut or unsafe pile for sampling.
3. Move the material to a clean, safe sampling location. Wait until unloading machinery is stopped and the operator has confirmed that staff may approach.
4. Take multiple small subsamples. Sample different locations and depths of the safely removed material rather than grabbing one attractive handful. For a large or variable feed source, follow the laboratory's specified number of increments; a quick five-handful check is not a universal laboratory protocol.
5. Mix without losing fine particles. Use a clean container or suitable clean surface. Reduce the sample carefully only if required by the laboratory.
6. Seal, label, and cool promptly. Remove excess air from appropriate bags, record the lot and time, and follow the laboratory's shipping instructions.

An established Alabama Cooperative Extension forage-sampling procedure describes collecting 20–30 small portions for a silage composite. The exact plan may differ with silo type, the sampling method, and the analyses requested.

What if the loader only removes one section of the face?

Then the collected material represents that section and unloading event, not automatically the entire bunker. Note the location and date. If there are meaningful differences between layers, harvest dates, or sections, use additional sampling events or separate samples instead of pretending the whole bunker is uniform.

The same principle applies to a silage facer. Samples can be collected from fresh material safely discharged during normal operation, after the machine is stopped and the sampling area is clear. Do not reach near moving blades, conveyors, or other equipment.

Should moldy or heating silage be included in the composite?

Not automatically. Do not blend clearly spoiled material into a normal nutrient sample just to create an average, and never return it to the ration. Isolate suspect feed and decide whether to reject it or arrange separate investigation. If the question is contamination of feed already consumed, the sampling plan must reflect that exposure and should be agreed with a laboratory or veterinarian.

Mycotoxins can occur in irregular pockets, so a negative result from one convenient sample may miss contamination. The University of Nebraska–Lincoln's Sampling and Testing Feed for Mycotoxins explains why these cases require particular care.

What Is the Correct Way to Sample a Total Mixed Ration (TMR)?

There is no single “best TMR sample” for every question. If your aim is overall nutrient composition, a well-collected composite may be appropriate. If you are troubleshooting an uneven mix, combining everything into one bag can hide the very difference you are trying to measure.

Goal 1: Check the nutrients actually delivered

Collect fresh TMR before cows have had an opportunity to sort it. Use multiple small portions spaced across the defined delivery or feed bunk, following a consistent collection method and the laboratory's instructions. Mix for a representative sample without allowing grain fines or chopped leaves to separate.

Penn State Extension describes collecting six to eight spaced grab samples from a freshly fed bunk for a nutrient-analysis composite in one troubleshooting procedure. Some farms and laboratories may specify a different number or a larger final sample, especially when long forage or cob fragments are present. The objective is representation, not hitting an arbitrary handful count. See Troubleshooting Problems with Low Milk Fat and Milk Protein.

Goal 2: Check mixing and discharge consistency

Take separate fresh samples from the beginning, middle, and end of the discharge route or mixing batch. Label each one and analyze or compare them separately. A single composite can show a reasonable average nutrient concentration even when individual feeding locations receive different proportions of forage and concentrate.

Start by comparing physical appearance and particle-size distribution using a standardized tool such as the Penn State Particle Size Separator. If results suggest genuine differences, review ingredient loading order, mixer fill level, mixing duration, knife condition, unload speed, and scale accuracy.

Under-mixing may leave clumps or poorly distributed ingredients. Excessive mixing can shorten particles and potentially change the physically effective fiber profile. Neither is diagnosed reliably from one composite laboratory report.

Goal 3: Find out whether cows are sorting

Keep the offered TMR and later refusals separate, and record exactly when both were taken. Compare particle-size distribution and feed behavior along with the amount of feed remaining. Refusals are not a useless sample: they are useful when the question is what cows selected or left behind, rather than what the mixer delivered.

Do not confuse this analysis with a routine nutrient sample. An individual cow's actual intake cannot be determined just by testing a pooled refusal sample.

Testing objective	Fresh TMR	Separate positions	Refusals
Average delivered nutrients	Yes, composite	Usually not necessary	No
Mixer and unloading consistency	Yes	Yes: start / middle / end	Optional
Feed sorting	Yes, baseline	When useful	Yes, later sample

Penn State's TMR management guidance highlights mixing time, ingredient weights, particle length, and dry matter as important contributors to ration consistency.

How Should You Take Representative Hay and Alfalfa Samples?

Use a proper hay probe and sample a clearly identified lot. A handful pulled from the surface does not reliably preserve the proportions of stems, leaves, and finer material inside the bales. This is particularly important for alfalfa because lost leaves can bias the nutrient result.

Sample the lot, not the easiest bale

For routine hay nutrient testing, about 15–20 representative bale cores per reasonably uniform lot is a common extension recommendation. The required number can vary with bale type, lot size, and the laboratory's protocol. Select bales systematically or randomly across the accessible lot, rather than always choosing the first row by the warehouse door.

• Small or large square bales: Core through the center of the short end into the bale, following probe and laboratory instructions.
• Round bales: Core through the curved side toward the center.
• Compressed imported alfalfa: Preserve the original harvest or supplier lot identity. Inspect and sample across relevant container or storage positions; do not assume all containers represent one homogeneous lot.
• Rain-damaged or suspect bales: Isolate and assess them separately. They should not quietly disappear into the routine composite if the purpose is to evaluate damage or contamination.

A sharp, correctly sized probe is preferable to pulling hand flakes. Keep all core material—including fragile alfalfa leaf fragments—in the collection container. Wisconsin Extension's hay sampling guidance explains core orientation and the commonly used 20-core approach.

What about a supplier's quality report?

A supplier's report can be useful, but it describes the sample and lot tested—not every bale that later arrives at your farm. For a purchase involving several containers or harvest lots, note exactly which shipment each result represents. If the contract relies on a particular nutrient specification, agree on lot definitions, an independent sampling method, and the dispute procedure before delivery.

If a farm does not own a proper probe, borrowing one or hiring a qualified sampler is better than presenting a surface grab sample as a representative laboratory sample.

How Do You Mix and Reduce Samples Without Changing Their Composition?

The quartering method can help reduce a mixed bulk sample, but it must not change the share of leaves, stems, grains, or fine particles that made up the original material.

A practical procedure for materials suitable for quartering is to:

1. Collect the required increments into a clean, dry container or onto a suitable clean surface.
2. Gently mix all components, including the fines that settle at the bottom.
3. Spread the material evenly and divide it into four equal sections.
4. Retain two opposite sections, combine them, and repeat only as needed.
5. Make sure fine particles are not left behind or blown away; pack the final amount specified by the laboratory.

Do not automatically quarter every sample. Some laboratories prefer to receive the complete collection of hay cores. A mycotoxin investigation can require a substantially larger composite than a routine nutrient test. Particle-size analyses may require an untreated fresh sample in a specified volume or mass. Ask the laboratory before grinding, drying, mixing, splitting, or discarding material.

The final sample size is not always 400 g. As one example, Dairy One's forage laboratory gives approximate standard amounts of 100 g hay, 300 g haylage, 450 g corn silage, and 400 g TMR, with extra quantities for certain tests. Those numbers belong to that laboratory's process; they are not universal rules.

How Often Should Silage and TMR Be Tested?

The right schedule depends on how variable the feeds are and what is at stake. Herd size alone is not enough to prescribe a universal weekly or monthly laboratory schedule. A large, stable operation may need fewer full nutrient rechecks than a smaller farm opening several different silage bags. Conversely, a high-producing herd can justify more frequent monitoring when ingredient variation is substantial.

A practical way to organize testing is to separate quick dry-matter monitoring from full laboratory analysis:

Situation	Sensible action
A known silage or wet-feed lot is stable	Monitor dry matter at an interval appropriate to observed variation; repeat full nutrient testing on a planned schedule
New bunker, bag, supplier, cutting, or harvest section	Review representative nutrient testing and update the ration database
Rain, moisture change, fermentation problem, or an unusual feed-out area	Check dry matter promptly; sample affected material and consider further tests
Sudden change in feed refusal, rumination, milk output, or manure	Investigate feed alongside water, cow health, heat stress, and other management factors
Suspected mycotoxin contamination	Isolate questionable feed and follow a risk-based sampling and testing plan rather than relying on a blanket weekly rule

For example, monthly full forage analysis for a stable 100–300-cow dairy or every two weeks for a high-throughput dairy with variable ingredients may be reasonable starting plans, not research-validated requirements. The farm's nutritionist should increase or reduce frequency based on the variability of results and actual management decisions.

Dry matter affects the feeder today

A moisture change can alter how much actual feed dry matter is delivered even when the mixer scale displays the same as-fed weight. Recheck ingredient weights when on-farm dry-matter measurements change. More complex ration adjustments should use current, credible lab results and a nutritionist's review—not a single surprising number taken out of context.

Which Laboratory Tests Are Worth Paying For?

Choose the tests based on the decision you need to make, not simply the longest menu of laboratory options.

Testing purpose	Useful measurements	Main caution
Basic forage ration formulation	Dry matter (DM), crude protein (CP), NDF, ADF, and relevant energy estimates	Compare nutrients on the same reporting basis
Corn silage quality	DM, starch, NDF, and, where useful, digestibility or kernel processing measurements	Starch percentage alone does not measure starch utilization
Silage fermentation questions	pH and a fermentation-acid profile as appropriate	pH alone does not fully describe fermentation quality
TMR delivery or sorting	DM, nutrient analysis where relevant, particle-size distribution	Average nutrient values can hide physical variation
Suspected soil contamination or mineral imbalance	Ash and targeted mineral analysis	High ash may point to soil contamination but is not a diagnosis by itself
Suspected toxins	Laboratory-recommended specific mycotoxins	Mold counts and a generic “negative” result are not equivalent to a comprehensive toxin screen

For a small dairy farm, a reliable forage DM and basic nutrient profile is often more useful than a long list of expensive tests with no plan to use the results. For a large farm, additional digestibility, fermentation, mineral, and physical-ration analyses can be valuable where they lead to management action.

Never compare as-fed and dry-matter percentages directly

A sample testing 3% crude protein as fed at 30% DM contains 10% crude protein on a DM basis. Comparing its 3% figure with another forage's 10% DM-basis value would be misleading.

As a general conversion:

Nutrient percentage on a DM basis = nutrient percentage as fed ÷ (DM percentage ÷ 100)

Oregon State University's forage-test interpretation guide explains this distinction. A high protein number does not necessarily mean a forage is the best choice: digestibility, fiber, starch, minerals, dry matter, and intake all matter.

How Should You Label, Store, and Ship Forage Samples?

Good sampling work can be undone by a poorly identified or deteriorated sample. Wet silage and TMR can change while sitting warm in a vehicle or shipping depot.

Each sample should carry a clear label with:

• Farm and sample ID.
• Feed type and defined lot or bunker section.
• Sampling date and time.
• Collection position or mixing batch if relevant.
• Test requested and any special concern.
• The person who collected it.

For silage and other wet feeds, seal promptly, minimize unnecessary air exposure, and use cooling or freezing as advised by the laboratory and the specific analysis. Samples intended for fermentation testing deserve especially prompt handling. For dry hay, a sealed sample kept cool and dry often does not need freezing. Do not dry, heat, or freeze a sample without confirming that the intended analytical method permits it.

Whenever possible, arrange shipping so samples reach the laboratory promptly rather than waiting in transit over the weekend. Dairy One's sample handling guidance and Penn State's silage-management guide describe different handling needs for dry forage, silage, and fermentation analysis.

For a larger dairy, use a consistent sample ID and one log that links sampling location → laboratory report → ration version → feeding date. For a small farm, a clean dedicated sampling corner with a covered box for tools, a labeling station, and access to suitable cold storage may be enough. A separate laboratory building is not essential.

What Should You Do When Two Feed Reports Disagree?

Do not immediately reformulate the whole ration around a surprising report. First make sure the values are genuinely comparable and the samples describe the same feed.

A useful troubleshooting order is:

1. Check the reporting basis: Are both reports on a dry-matter basis or both as fed?
2. Check lot identity: Same field, harvest, bunker section, or supplier delivery?
3. Check sampling and handling: Were both samples collected with comparable methods and stored properly?
4. Check real-time moisture: If the feed is wetter or drier, update as-fed ingredient weights promptly with the nutritionist's guidance.
5. Repeat a representative sample if needed: Retesting a poorly collected old sample may only repeat the same bias.
6. Then review the ration: Compare verified results with actual intake, refusals, milk performance, and other feed ingredients before making larger changes.

If feed is visibly spoiled or contamination is suspected, hold it while the issue is investigated. That safety decision should not wait for a routine nutrient retest.

For farms using TMR mixers, this order often saves money: sampling method first → feed moisture second → mixer scale, loading order, and mixing performance third. A mixer may be functioning properly even when incoming forage composition has changed.

How Does NexAgri Support Better Feed-Management Decisions?

NexAgri Solutions supplies TMR mixers and feeding equipment and supports dairy-farm feeding layouts, including relevant loading, weighing, discharge, and feeding arrangements. These systems help implement a ration consistently after its ingredient data has been checked.

A laboratory report will not fix an incorrect loading sequence, and a high-quality mixer cannot make an unrepresentative sample accurate. In a new dairy project, it is worth planning a clean sampling location near the forage receiving or TMR area, with safe machinery access, a work surface, sample identification, and appropriate temporary storage.

Use a qualified laboratory for analysis and specialist suppliers for sampling tools. For the equipment layout, NexAgri can help review mixer loading, weighing, discharge and feeding routes around a safe sampling area.

Forage, Silage, and TMR Sampling Checklist

Stage	What to check
Plan	Is the goal nutrient analysis, mixing uniformity, sorting, or contamination investigation?
Identify	Is this one well-defined lot? Are the source and date recorded?
Collect	Are enough representative increments collected safely?
Separate	Must locations or suspect material remain separate rather than becoming one average?
Reduce	Will mixing or quartering preserve the original particle and leaf proportions?
Package	Does the laboratory want a specific amount, bag type, and temperature condition?
Label	Can the result be traced back to the exact feed and feeding event?
Interpret	Are units and dry-matter basis consistent, and is the result actionable?

Frequently Asked Questions

How many corn silage samples should I collect?

There is no universal nine-point grid or one handful count. Collect multiple representative subsamples of safely removed fresh feed, following the laboratory's protocol and the feed area being evaluated. Do not sample by standing close to an unstable bunker face.

Should TMR samples come from fresh feed or refusals?

Use fresh TMR to test the ration delivered. Use refusals separately to investigate sorting and what remained after cows ate. Do not combine these two purposes in one bag.

Can one TMR composite show whether a mixer is uniform?

Not reliably. A composite gives an average. Check separate positions such as the beginning, middle, and end of unloading when investigating mixing consistency.

How many hay bales should be sampled for a forage test?

A common recommendation is 15–20 hay cores from randomly selected bales in a uniform lot, although specific labs and bale types may call for a different plan. Use a proper core probe rather than hand-pulled flakes.

Does every forage sample need to weigh 400 g?

No. Required mass varies by feed type, laboratory, and testing method. Confirm the requirement before reducing or shipping a sample.

Should silage samples be refrigerated or frozen?

Wet samples should be protected from delay, oxygen exposure, and heat, but cooling or freezing instructions depend on the analysis and laboratory. Contact the lab—especially for fermentation testing, mycotoxins, or longer shipping times.

What is the difference between a forage nutrient test and a mycotoxin test?

A nutrient test describes feed composition. A targeted mycotoxin test looks for named toxins. A normal nutrient profile does not prove a feed is free of contamination, and visible mold does not identify which toxins are present.

How often should a dairy farm update forage tests?

Use a schedule based on lot changes and actual feed variability, supported by regular dry-matter checks. Retest after major ingredient changes, abnormal spoilage, or unexplained feeding performance problems rather than relying on herd size alone.

Conclusion

Good feed decisions start with samples that represent the right material. Define the lot, match the sampling method to the question, collect safely, avoid losing fines during mixing or reduction, and preserve each sample until the laboratory receives it.

For silage, the essential improvement is sampling freshly removed feed away from the bunker face. For TMR, it is knowing when to composite and when to keep samples separate. For hay, it is consistent core sampling across a defined lot.

The laboratory can only analyze what arrives in the bag. A disciplined sampling routine—and a clear record connecting each result to the feed actually delivered—makes those numbers useful for a real farm.