Feed Mixer Wagon Equipped with a Magnet on the Discharge Arm – Why Is It Worth It?

Metal “surprises” in feed occur more often than many farmers expect: a piece of baling wire, a staple, a screw, a fragment of chain, metal shavings from machinery. In a TMR ration, these objects can easily go unnoticed and end up directly on the feed table.

That is why more and more farms choose a feed mixer wagon equipped with a magnet on the discharge arm (in the unloading zone). It is a simple component that acts as the “last filter” before the feed is delivered to the animals.

Where Does Metal in TMR Come From?

The most common sources of metal contamination in feed include:

  • wire or netting from bales (especially during fast cutting and processing),

  • staples, nails, screws from pallets, crates, fences,

  • worn machine parts (clips, springs, chain fragments, bolts),

  • metal shavings after service or repairs,

  • small metal debris from the yard that ends up in silage or the bunker.

The problem is that metal objects are not always visible in TMR – they can easily “disappear” within the feed structure.

What Is a Magnet on the Discharge Arm and Where Does It Work in a Feed Mixer Wagon?

In simple terms, it is a magnetic separator installed in the feed discharge area – usually on the discharge arm or the component guiding feed toward the trough or feed table (depending on the machine design).

How does it work in practice?

  1. The feed is fully mixed inside the hopper.

  2. During discharge, the TMR passes through the area where the magnet is installed.

  3. Ferromagnetic metal elements (steel/iron) are attracted and remain on the magnet instead of reaching the animals.

Importantly, a magnet placed at the discharge point is often treated as the “last line of protection” – right at the end of the feeding process.

Why Equip Your Feed Mixer Wagon with a Magnet? Key Benefits

1. Reduces the Risk of Metal Ingestion

Its primary function is to limit the risk of wire, screws, or other metal pieces being ingested by cows. In practice, it is part of preventive herd health management related to foreign objects in feed.

2. Acts as a Final Quality Control Before Feeding

A feed mixer wagon prepares the ration, but a discharge magnet provides an additional layer of control – especially when feed ingredients come from multiple sources and are handled by different workers.

3. Helps Identify Problems on the Farm

If the magnet regularly collects metal, it is a signal that:

  • there may be mistakes during bale opening,

  • a machine component could be wearing out,

  • yard organization or internal procedures need improvement.

In many cases, this diagnostic function is even more valuable than the protection itself – it helps eliminate the source of contamination.

4. Low Maintenance During Operation

This is not electronics or a sensor requiring calibration. A magnet simply works. The only condition is regular cleaning (see below).

5. Complements Other Safety Solutions

Many farms use additional protection measures at other feed flow points. A magnet on the discharge arm is an excellent complement because it operates exactly where the feed leaves the mixer wagon.

6. A Practical “Feed Safety” Argument

In daily practice: fewer concerns, less risk of invisible losses, and greater peace of mind during routine feeding.

What Does the Magnet Catch – and What Doesn’t It Catch?

Typically captures:

  • wires, nails, screws, bolts,

  • steel or iron shavings,

  • small fragments of metal components.

Does NOT capture:

  • plastic, glass, stones, wood,

  • aluminium,

  • certain types of stainless steel (depending on grade – not all are magnetic).

Therefore, a magnet does not replace proper feed management and cleanliness. It is a safety feature, not an excuse for poor procedures.

Why Is a Magnet at the Discharge Point Often More Effective Than “Somewhere Inside”?

Metal objects can move during the mixing process. In the discharge zone, the situation is simple: feed passes very close to the magnet, and you can clearly see the result.

Additionally:

  • the location is usually easier to access for inspection,

  • it is easier to develop a routine: “after feeding, I check the magnet.”

How Often Should You Clean the Magnet on a Feed Mixer Wagon?

The best rule: as often as metal appears. In practice, a simple standard works well:

  • daily (in intensive operations using baled silage),

  • at least several times per week,

  • always after a “suspicious” situation (broken pallet, machine repair, new feed batch).

Simple Cleaning Procedure

  1. Stop the machine and secure it against accidental start.

  2. Wear gloves (metal pieces can be sharp).

  3. Remove collected elements and place them in a “findings box.”

  4. Ask yourself: where did this come from?

Pro tip: If you collect metal findings in one container for a month, you will have valuable data to improve procedures on your farm.

When Is It Worth Equipping a Feed Mixer Wagon with a Magnet?

This solution makes particular sense if:

  • you feed large amounts of baled silage,

  • more than one person prepares feed,

  • you operate intensively and often work under time pressure,

  • you have previously experienced metal contamination,

  • you want to add a simple yet effective quality control element.

In practice, magnets are popular both in new machines and as a retrofit option.

FAQ – Magnet in a Feed Mixer Wagon

Will a magnet on the discharge arm catch bale wire?
If it is steel (ferromagnetic), very often yes. Efficiency depends on feed flow distance from the magnet and its design.

How often should the magnet be cleaned?
A daily or every-few-days routine is safest. A magnet covered with metal works less effectively.

Does the magnet affect TMR mixing quality?
No. It works in the discharge zone and does not interfere with the mixing process. It is purely a safety filter.

Magnet on the discharge arm or magnet inside the hopper?
These are two different approaches. A discharge magnet acts as the final inspection point and is easy to check regularly. In many farms, both solutions complement each other.

Can it be installed in older feed mixer wagons?
Often yes – it depends on the machine design and available mounting space. The key is ensuring that feed passes as close as possible to the magnet.

As a Polish manufacturer of feed mixer wagons, ZAMET recommends equipping your feed mixer wagon with a magnet on the discharge arm. It is a small component that can stop wire, screws, or metal shavings and significantly increase feed safety.

In new feed mixer wagons, we can install this solution at the factory, and in many cases, it can also be retrofitted to existing machines.