Total Mixed Ration Mixing Mistakes

A well-balanced ration can fail at the mixer. Loading order, mixing time and equipment wear all change what the cow actually gets.

Key points

Use the same loading order every day.
Watch mixing time to protect fiber length.
Keep scales, knives and augers in good condition.
Do not overfill the mixer.
Check particle size and sorting at the bunk.

Why mixing matters

A total mixed ration, or TMR, is meant to give every cow the same balanced bite. When the mix is uneven, cows at one end of the bunk get a different diet than cows at the other, and the formulation is only a rough guide.

Mixing problems often look like feed problems or cow problems. Before blaming a forage or a health issue, check how the feed is going into the wagon and coming out.

Loading order errors

Most mixers perform best when ingredients go in a consistent order. The right order depends on your mixer type, so follow the manufacturer's guidance and your nutritionist's advice, and then keep it the same every day.

Dropping small-quantity ingredients like minerals in a dry corner or on top of wet feed can leave pockets of concentrated additives. Ingredients that are fed in small amounts need to be spread through the load, not dumped in one spot.

Write down the loading order and post it at the mixer
Add small-inclusion ingredients where they will mix well
Keep the order the same from load to load

Overmixing and undermixing

Undermixed feed shows up as clumps of one ingredient and uneven samples. Overmixed feed shows up as chopped-up forage, lost fiber length and a fine, dusty mix that cows sort through easily.

Fiber length matters because it keeps cows chewing and the rumen buffered. If the mixer is shredding the forage, the ration can be correct on paper and short on effective fiber in practice. Ask your nutritionist what mixing time works for your feeds and your wagon.

Scales, equipment, overfilling and delivery

Accuracy depends on the scale. A scale that drifts, a loader operator who rounds off loads, or an indicator that is hard to read all add error. Over a month, small errors add up to a different diet.

Knives and augers wear. Worn knives tear instead of cutting and leave stringy forage, and worn augers can leave dead spots. Check the equipment on a schedule, and follow the manufacturer's lockout and safety procedures before any inspection or repair.

Overloading the wagon makes mixing poor no matter how long it runs. Feed at the top rarely gets the same treatment as feed at the bottom. Delivery matters too. Feed that is dumped in a heap, or fed in an uneven line, will give some cows more than others. Push feed up often so every cow has access.

Simple checks you can do

Particle separator testing is a practical, low-cost way to see what is happening. Test samples from the fresh feed and again later in the day, and compare. If the later sample has far more long particles, cows are sorting.

Check feed from the front, middle and back of the bunk. Look for ingredient clumps, mineral pockets and dry or wet spots. Keep refusals and weigh-backs on record so you can see trends.

Cows show uneven mixing in several ways. Some cows look fine while others at the far end of the bunk look thin or have loose manure. Milk can swing from day to day when different loads differ. Bunk refusals that look different at one end than the other point to sorting or poor distribution. Track these signs alongside your mixing records. If a problem appears on days when a certain person mixed or a certain ingredient was low, the pattern gives you a place to start.

Use a particle separator on fresh feed
Compare samples from different parts of the bunk
Weigh back refusals
Check scale accuracy on a regular schedule

Training the people who load the wagon

The best procedure fails if the person loading it does not know why it matters. Walk new employees through the loading order, explain what happens when ingredients are skipped or doubled, and let them see a particle separator test on their own load.

Post the recipe where the loader operator can read it, and make it easy to report a problem. If a feed runs short, the operator should know who to call instead of improvising a substitute. Substitutions made on the fly are one of the most common ways a ration changes without anyone noticing.

Written recipe at the mixer
Clear rule for shortages: call before substituting
Regular refresher with the nutritionist
Record each load and any changes

What to ask your nutritionist

Ask for a written mixing procedure for your wagon, target particle size ranges for your feeds, and what to watch for when forage moisture changes. Request a visit during mixing so they can see the process rather than only the printed ration.

Also ask about how often feed ingredients should be re-sampled, since a change in dry matter can make a load heavier or lighter than the scale says it is.

When to get help: Ask your nutritionist to observe a mixing session and review your procedure. Call your veterinarian if the herd shows digestive upset, off-feed behavior or sudden drops in milk.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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