Why cows love to brush
Natural grooming behaviour explained
It might surprise some farmers to learn just how strongly dairy cows are driven to groom themselves; but in fact, this is a completely natural behaviour that cows share with many other animal species, often tied to their deeply-rooted biological needs for comfort, stress relief, and overall wellbeing.
A 2018 study by researchers at the University of British Columbia (UBC) found that dairy cows work just as hard to access a mechanical brush as they do to access fresh feed. With food motivation is the benchmark for measuring how important a resource is to an animal, the fact that brush access was rated equally in the controlled experiment says a great deal about the importance of grooming to them as a natural need[i].
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A natural drive, often restricted
In a pasture-based environment, cows can groom freely by rubbing against rough surfaces like trees to relieve itchiness that builds up from insects, mud, and general daily exposure. However, in housed or compost shed systems, those natural outlets are often unavailable.
Without an appropriate alternative, cows tend to redirect the behaviour toward other on-farm infrastructure such as walls, water troughs, and fence posts or gates. It gets the itch partially scratched, but it also carries a real risk of injury and leaves the underlying need largely unmet.
This makes a mechanical cow brush such a meaningful enrichment addition to allow cows to perform natural grooming behaviour that would otherwise be restricted.
A study published in the Journal of Dairy Science found that when given access to a mechanical brush, cows spent approximately five times more time grooming than when none was available - a strong indicator of previously unmet behavioural need rather than simple preference[ii].
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How cows groom: Which body areas do cows prefer to brush
Cows tend to focus their grooming activity on the areas most difficult to reach on their own, particularly the head, neck, back, and tail base, and they do so with considerable enthusiasm.
The same Journal of Dairy Science research found that cows given access to a mechanical brush not only groomed more often, with scratching events twice as frequent, but also averaged around seven minutes per day using the brush when given the opportunity.
The force they apply is equally telling, as UBC researchers have recorded individual cows pushing weighted gates up to 59kg to gain access to a grooming brush, underscoring just how motivated they are to meet this need.
Taken together, the data points show that when given access to the right grooming outlet, the cows will use it, and use it well.
Why brushing matters for welfare
A cow that is comfortable and low-stress is generally a healthier, more productive one. Regular brushing plays a meaningful role in that.
Beyond a clean coat, brushing stimulates blood circulation, supports healthier skin condition, and contributes to reduced stress levels, all of which have well-documented links to immune function and overall herd health.
Research has also found that a drop in grooming activity can serve as an early warning sign for mastitis and lameness, making brush behaviour a quiet but useful signal for farmers to watch[iii].
For healthy and contented cows, grooming is therefore not an optional extra. It is an essential behaviour that requires a reliable, safe, and robust outlet. For that, farmers need a mechanical brush that mimics natural scratching surfaces while ensuring safety and hygiene, as well as the physical demand cows place on it everyday.
Understanding the science behind it is the first step toward meeting that need practically and consistently. In the next article in this series, we will take a closer look at how the Lely Luna automatic cow brush is designed to meet exactly that need, across a range of farm sizes and shed configurations.
REFERENCES:
[i] Cows are highly motivated to access a grooming substrate
[ii] Short Communication: Usage of Mechanical Brushes by Lactating Dairy Cows
[iii] Short communication: Detection of lameness in dairy cows using a grooming device
