A good Total Mixed Ration is not defined by how long the mixer runs or how full the tub looks.
The real target is consistency.
The ration delivered at the beginning, middle, and end of unloading should be as similar as possible, and cows should have limited opportunity to sort the mix after it reaches the feed bunk.
That depends on several factors working together:
Loading Order → Batch Size → Mixing Time & Speed → Ingredient Moisture → Mixer Condition → Feed Bunk Management
At NexAgri Solutions, we normally treat TMR preparation as a complete feeding workflow rather than simply a mixer-selection problem.
A large mixer cannot correct poor loading practices.
And a perfectly mixed ration can still fail if cows cannot access fresh feed consistently.
What Is a Good TMR?
A Total Mixed Ration combines forage, concentrates, minerals, byproducts, and other ingredients into one mixed ration.
The purpose is not to create a mathematically “perfect mouthful” every time.
The practical goals are to:
- Improve nutrient consistency
- Reduce selective feeding
- Deliver physically effective fiber
- Maintain consistent dry matter intake
- Reduce large changes in nutrient intake throughout the day
- Make group feeding easier to manage
Even a well-formulated ration can perform poorly if:
- Ingredient weights are inaccurate
- Forage dry matter changes
- The mixer is overloaded
- Mixing time changes every day
- Long forage is overprocessed
- The ration is too dry and easy to sort
- Feed is not pushed back toward cows
That is why TMR management starts with consistency rather than one fixed formula.
If TMR Is Mixing Poorly, What Should You Check First?
When a customer says:
“The TMR is not mixing evenly.”
we prefer to check the easiest operating variables first before assuming the mixer itself is defective.
A practical troubleshooting order is:
- Loading order and batch size
- Mixing time and mixer speed
- Cow sorting behavior
- Ingredient moisture and physical condition
- Knives, augers and weighing system
- Mixer capacity and available power
This order matters.
Replacing knives will not solve a loading-sequence problem.
Increasing mixing time will not fix an overloaded mixer.
And buying a larger mixer will not solve inconsistent ingredient moisture.
Loading Order Should Follow the Mixer and Ingredients
There is no universal loading sequence that works for every TMR mixer.
The correct order depends on:
- Vertical or horizontal mixer design
- Auger configuration
- Knife arrangement
- Ingredient particle size
- Ingredient density
- Ingredient moisture
- Whether long forage needs cutting
- Whether the mixer runs during loading
The basic principle is:
Look at the machine and the ingredients first, then decide the sequence.
Long Forage Needs Processing—But Do Not Make Every Ingredient “Wait”
Long hay or straw may need additional cutting time.
But this creates a common mistake.
Operators load:
Long Hay → Silage → Concentrates → Minerals
and then run everything for a long time simply because the hay still needs cutting.
The result may be:
- Hay reaches the correct length
- Silage becomes overprocessed
- Effective fiber becomes too fine
- Concentrates are mixed much longer than necessary
A better approach is to give ingredients only the processing time they actually need.
Depending on the mixer design, this may mean processing long forage before adding ingredients that require less mechanical action.
Always confirm the final procedure against the mixer manufacturer's operating instructions and the actual TMR result.
Mixing Time Is Not a Universal Number
A rule such as:
Mix every TMR for exactly 8 minutes.
sounds simple but is not reliable.
Mixing time depends on:
- Mixer type
- Batch size
- Ingredient sequence
- Long-forage content
- Auger speed
- Knife condition
- Moisture
- Ingredient density
Both under-mixing and over-mixing create problems.
Under-Mixing
Possible signs include:
- Concentrate pockets
- Clumps of long forage
- Different material at different parts of the bunk
- Minerals distributed unevenly
Over-Mixing
Possible signs include:
- Excessive fines
- Loss of long particles
- Reduced physical fiber
- TMR structure changing between batches
The better standard is:
Use enough mixing time to achieve uniform distribution without unnecessarily reducing particle size.
Then keep that procedure consistent from batch to batch.
Mixer Speed Also Matters
Mixing time cannot be evaluated separately from auger or rotor speed.
A mixer operating faster may process ingredients differently from the same machine operating more slowly.
When troubleshooting, record:
- Loading sequence
- Mixer RPM / PTO speed
- Mixing time
- Batch weight
- Ingredient condition
If one of these changes, the final TMR may also change.
TMR Moisture Is a Management Tool, Not a Fixed Number
Moisture influences both mixing and sorting.
A very dry TMR can allow:
- Fine concentrate particles to separate
- Long forage to be sorted
- Minerals to settle
- Cows to selectively consume preferred particles
An excessively wet ration can also create:
- Poor handling
- Reduced palatability in some situations
- More rapid heating or spoilage depending on ingredients
- Difficulty interpreting particle separation
Many dairy TMRs may operate around 45–55% dry matter as a practical reference range.
But that should not become a universal target.
The correct moisture depends on:
- Silage moisture
- Wet byproducts
- Forage type
- Concentrate level
- Climate
- Feed stability
- Cow response
The better question is:
Is the ration wet enough to hold the ingredients together without creating another feeding problem?
Can Water or Molasses Be Added to a Dry TMR?
Yes, where appropriate.
Water, molasses, whey, or other approved liquid ingredients can sometimes help reduce sorting and bind fine particles to forage.
But do not simply pour a large amount of water into the mixer.
Use a controlled process:
Measure Ingredient Moisture
↓
Estimate Current TMR Dry Matter
↓
Calculate Required Liquid Addition
↓
Make a Small Adjustment
↓
Mix and Inspect
↓
Check Cow Sorting
↓
Adjust Again if NeededWater should solve a measurable problem.
It should not be added simply because a ration “looks dry.”
Particle Size Is More Useful Than One Chop-Length Number
There is no single forage chop length that guarantees a good dairy TMR.
The final ration is affected by:
- Harvest chop length
- Processing
- Storage
- Mixer knives
- Mixing time
- Loading sequence
- Cow sorting
This is why evaluating the finished ration is often more useful than specifying that every forage must be exactly 2 cm or 3 cm long.
Long particles can support rumination.
But excessively long particles can also make sorting easier.
Very fine particles may improve mixing but reduce the physical structure of the ration.
The goal is balance.
Use a Particle Separator to Check the Final TMR
A Penn State Particle Separator (PSPS) can be used as a practical field tool.
One commonly used TMR reference range is approximately:
| PSPS Layer | Typical TMR Reference |
|---|---|
| Upper >19 mm | 2–8% |
| Middle 8–19 mm | 30–50% |
| Lower 4–8 mm | 10–20% |
| Bottom <4 mm | 30–40% |
These values should be treated as reference ranges—not a universal ration specification.
The correct distribution still depends on:
- Forage source
- Ration formulation
- Production group
- Nutritionist recommendations
- Actual cow response
The most useful part of PSPS testing is often not whether one sample reaches an exact number.
It is comparison.
Three Simple Ways to Check Whether TMR Is Actually Mixed Well
1. Compare the Beginning, Middle, and End of Unloading
Take samples from:
- First feed discharged
- Middle of discharge
- Last feed discharged
Visually compare:
- Long forage
- Fine material
- Moisture
- Ingredient distribution
If the first and last sections look very different, mixer uniformity or loading procedure should be investigated.
2. Use PSPS at Several Locations
Run the same samples through a particle separator.
Large differences between locations may indicate:
- Under-mixing
- Poor unloading uniformity
- Incorrect loading order
- Overloaded mixer
The purpose is consistency across the entire batch.
3. Compare Fresh TMR With Refusals
This is one of the most useful checks.
Take a fresh TMR sample immediately after feed delivery.
Then compare it with feed remaining later in the day.
If the refusal contains noticeably more long forage while fine material has disappeared, cows are sorting.
That may point to:
- TMR too dry
- Particle length too long
- Poor mixing
- Insufficient bunk space
- Long periods without feed
A ration can leave the mixer correctly and still become nutritionally inconsistent because of cow sorting.
Practical TMR Troubleshooting Table
| What You See | Possible Causes | What to Check First |
|---|---|---|
| Cows leave long forage behind | Long particles, dry mix, sorting | PSPS, moisture, chop length |
| First unload differs from last unload | Poor mixing uniformity, loading issue, mixer fill | Batch size, loading order, mixing procedure |
| Large concentrate pockets | Under-mixing or poor loading sequence | Mixing time, ingredient order |
| Excessive fines | Over-mixing, aggressive knives, long mixer runtime | Mixing time, knives, RPM |
| TMR heats rapidly in bunk | Ingredient spoilage, warm weather, long exposure | Silage stability, delivery frequency, feed temperature |
| Daily refusals change sharply | Ingredient DM changed, delivery amount incorrect, intake change | Forage DM, batch weight, cow numbers |
| TMR varies between batches | Scale error, operator variation, changing DM | Scale calibration, written SOP, ingredient testing |
| Cows rush the bunk then run out of feed | Poor feed availability or delivery strategy | Delivery amount, push-up, bunk access |
| Mineral/fine material separates | Mix too dry or poor distribution | Moisture, liquid addition, loading order |
Use the table to identify where to start.
Do not change five variables at the same time.
How to Size a TMR Mixer Correctly
Cow numbers alone should not determine mixer capacity.
Two farms with 300 cows can require very different mixer sizes.
Why?
Because their TMR may have different:
- As-fed intake
- Bulk density
- Forage percentage
- Moisture
- Feeding frequency
- Number of feeding groups
- Batch strategy
The correct starting point is the largest single batch.
Step 1: Calculate the Largest Batch Weight
For each feeding group:
Batch As-Fed Weight
=
Number of Cows
×
As-Fed Intake per Cow
÷
Number of Feedings for That GroupDo this for every group.
Then identify the largest batch the mixer needs to prepare.
Step 2: Measure Actual TMR Bulk Density
Do not rely only on a generic density value.
A high-silage TMR may have a very different bulk density from a ration containing:
- Large amounts of dry hay
- Straw
- Wet byproducts
- High concentrate levels
Whenever possible, use a measured or validated bulk density from the actual ration.
Step 3: Convert Batch Weight Into Volume
Use:
Required Batch Volume
=
Largest Batch As-Fed Weight
÷
Actual TMR Bulk DensityFor example, if the batch weighs more but has a dense, wet ration, it may require less physical volume than a lighter, bulky dry-forage ration.
This is why:
Head count calculates feed weight. Bulk density and batch strategy determine mixer volume.
Step 4: Apply the Mixer's Usable Fill Factor
Mixer brochures may use several different volume terms:
- Geometric volume
- Rated volume
- Struck-full volume
- Usable mixing volume
These are not necessarily the same.
So the final selection should be:
Required Rated Mixer Volume
=
Required Batch Volume
÷
Usable Fill FactorBut the usable fill factor should come from:
- Manufacturer specification
- Mixer type
- Actual field mixing result
—not from one universal 85% rule.
Why Both Under-Filling and Over-Filling Can Cause Problems
Over-Filling
If too much material is loaded:
- Feed may stop circulating properly
- Ingredients may remain in unmixed pockets
- Augers cannot lift and fold material effectively
- Power demand increases
Under-Filling
A batch that is too small can also mix poorly because some mixers need a minimum amount of material for proper circulation.
The correct fill level is therefore:
The range where that specific mixer produces a repeatable, uniform TMR.
Not:
“Always fill it to 85%.”
TMR Mixer Selection Checklist
Before choosing a TMR mixer, confirm:
- Largest feeding group
- Largest single batch weight
- Feeding frequency
- Number of rations
- Actual bulk density
- Long forage content
- Required forage processing
- Tractor or motor power
- Loading height
- Barn door clearance
- Feed alley width
- Discharge direction
- Future herd expansion
Mixer capacity is only one part of equipment selection.
The machine still has to physically operate inside the farm.
Feed Bunk Management Starts After the Mixer Stops
A uniform ration leaving the mixer does not guarantee uniform intake.
Feed must remain:
- Accessible
- Fresh
- Close to the cow
- Difficult to sort
- Available for weaker animals
A complete feeding system therefore combines the mixer with good dairy feeding equipment and consistent bunk management.
1. Keep Fresh Feed Available
The first priority is simple:
Cows should not repeatedly find an empty bunk.
Long periods without feed can increase competition when fresh TMR finally arrives.
That encourages:
- Aggressive bunk behavior
- Large meals
- Sorting
- Uneven access between dominant and weaker cows
The objective is not unlimited waste.
It is consistent access.
2. Push Feed Back Frequently
Even when there is enough TMR in the bunk, cows push it away while eating.
Once feed becomes difficult to reach, available feed and accessible feed are no longer the same thing.
Frequent push-up helps return TMR to the feeding line.
Push-up frequency should respond to:
- Cow density
- Feeding frequency
- Bunk design
- Group behavior
- How quickly cows push feed away
Do not rely only on a fixed “every three hours” schedule.
3. Provide Enough Feed Space
Bunk competition increases when too many cows share too little feeding space.
For commercial planning where reduced competition and simultaneous access are priorities, approximately:
0.75–1.0 m of feed space per cow
can be used as a practical design range, especially for sensitive groups.
The exact requirement should still consider:
- Group type
- Headlock design
- Stocking density
- Feeding frequency
- Cow size
- Whether all cows need simultaneous access
Cattle headlocks can help organize cow position and reduce lateral interference, but headlocks cannot correct excessive stocking.
4. Use Refusals as a Management Signal
Refusal percentage should not become a rigid target.
The remaining feed tells you something about:
- Delivery amount
- Intake
- Ingredient dry matter
- Cow numbers
- Weather
- Ration palatability
For high-producing dairy groups, approximately 1–3% refusals can be used as one common management reference.
But the correct level depends on the farm.
The important part is daily consistency.
A sudden change from:
2% → 7%or:
2% → 0%deserves investigation.
5. Time Fresh Feed Around Cow Behavior
Fresh feed delivery should match the farm's daily routine.
Many cows show strong feeding activity:
- After milking
- After fresh feed delivery
- During cooler periods in summer
Where practical, providing fresh feed after milking can encourage cows to remain at the feed bunk before lying down.
This also makes cow traffic and feeding management work together instead of independently.
6. Watch Summer Feed Heating
Hot weather changes TMR management.
Warm, humid conditions can accelerate heating and spoilage, particularly in rations containing unstable silage or wet byproducts.
During summer, check:
- TMR temperature
- Smell
- Visible heating
- Bunk residence time
- Refusals
- Ingredient stability
Possible adjustments include:
- Smaller, more frequent deliveries
- More frequent bunk cleaning
- Avoiding preparation too far in advance
- Improving silage feed-out
- Adjusting unstable ingredients
Dairy barn fans can improve cow comfort at the feed line, but they do not prevent spoiled TMR.
Feed stability still needs to be managed separately.
Daily TMR Quality-Control Routine
A complicated laboratory program is not required to catch every feeding problem.
A simple daily system can identify many issues early.
Before Mixing
Check:
- Forage dry matter changes
- Ingredient availability
- Scale zero
- Mixer condition
- Knife and auger condition
During Loading
Check:
- Correct ingredient
- Correct weight
- Correct sequence
- Batch total
- Mixer RPM
After Mixing
Check:
- Beginning / middle / end uniformity
- Particle distribution
- Moisture
- Visible clumps
At the Bunk
Check:
- Feed availability
- Sorting
- Push-up
- Heating
- Refusals
Next Day
Record:
- Refusal weight
- Cow numbers
- Feed delivered
- Ingredient DM changes
- Any ration adjustment
The objective is to make each day's feeding process repeatable.
A Better TMR Operating Logic
Instead of managing feeding with fixed numbers, use this sequence:
Confirm Ration & Ingredient DM
↓
Set Correct Loading Sequence
↓
Prepare Correct Batch Size
↓
Mix to Consistent Distribution
↓
Check Beginning / Middle / End
↓
Deliver Evenly
↓
Keep Feed Accessible
↓
Check Refusals & Sorting
↓
Adjust Next BatchThis turns TMR feeding into a feedback loop.
Common TMR Management Mistakes
Mistake 1: Choosing a Mixer Only by Cow Count
Cow count determines feed demand.
It does not directly determine mixer volume.
Mistake 2: Filling the Mixer to One Universal Percentage
Different mixer designs have different usable working ranges.
Mistake 3: Using the Same Loading Sequence for Every Mixer
Loading should match both the machine and the ingredients.
Mistake 4: Mixing Longer Because the TMR “Looks Better”
More mixing can eventually reduce particle size too much.
Mistake 5: Ignoring Forage Dry Matter Changes
If silage moisture changes but as-fed loading weight does not, the ration delivered to cows changes.
Mistake 6: Checking Only One TMR Sample
One sample cannot tell you whether the first and last part of the batch are the same.
Mistake 7: Looking Only at Fresh TMR
Refusals show what cows actually chose not to eat.
Mistake 8: Using Headlocks to Compensate for Overcrowding
Headlocks reduce interference.
They do not create additional feed space.
Mistake 9: Letting the Bunk Run Empty Regularly
A technically correct ration is not useful if cows cannot access it consistently.
Conclusion
Good TMR feeding is not about finding one perfect mixing time, one perfect moisture percentage, or one mixer size per number of cows.
It is about repeatability.
A practical system follows this logic:
Correct Ingredients → Correct Batch → Correct Loading → Consistent Mixing → Even Delivery → Continuous Feed Access → Monitor Sorting & Refusals
When troubleshooting, start with the variables that are easiest to correct:
Loading Order → Batch Size → Mixing Time & Speed → Ingredient Condition → Hardware → Equipment Selection
When selecting a mixer, start with:
Largest Batch Weight → Actual Bulk Density → Usable Mixer Volume
not simply herd size.
And after the TMR reaches the bunk, continue managing:
Fresh Feed Availability → Push-Up → Feed Space → Refusals → Feeding Time → Summer Stability
The best TMR system is not the one with the largest mixer or the longest mixing cycle.
It is the one that delivers the same ration, consistently, to every group every day.
