Low milk diets push calves to prioritise food over play, study finds

Dairy calves fed higher milk allowances are more likely to play, while restricted feeding drives them to prioritise food-seeking behaviour, new research has found.

The study, led by the University of Bristol and published in Scientific Reports, compared calves given 12 litres of milk a day with those fed 6 litres — a level typical on many dairy farms — highlighting how standard feeding practices may influence behaviour and welfare.

The findings raise questions about whether current feeding approaches fully support calf welfare on commercial farms.

In maze-based tests designed to assess motivation for milk, calves on lower allowances completed tasks faster and showed stronger recall, indicating a heightened drive to find food.

By contrast, calves given more milk were less focused on the feeding task and instead showed greater levels of play behaviour and general activity.

The trial involved two groups of 10 calves monitored over a three-week period, offering insight into how feeding levels shape both behaviour and motivation.

Lead author Jillian Hendricks said: “The study is among the first to show that hungry animals will trade-off play to prioritise finding food.”

She added the findings expand understanding of how hunger affects behaviour, noting it “suppresses other competing motivations and emotions, like play opportunities”.

Importantly, the research suggests feeding levels influence not just physical development but also the ability of calves to express natural behaviours.

Dr Ben Lecorps, co-author and animal welfare scientist at the University of Bristol, said the findings have practical implications for the dairy sector.

He said: “The key takeaway for dairy farmers is that the standard milk allowance for calves may disrupt other important behaviours, which indicate that they may experience hunger.”

He added: “The research suggests feeding calves more may not only be beneficial as it suppresses hunger, but also because it contributes to the expression of other important behaviours like play.”

These behaviours are widely recognised as indicators of animal welfare, suggesting restricted feeding may limit opportunities for natural activity in young calves.

All calves were without milk for 16 hours before testing, reflecting standard twice-daily feeding on many farms.

Even so, calves fed higher milk allowances still prioritised play over feeding behaviour.

Dr Lecorps said: “Despite this long period without milk, calves fed more still prioritised playing. This tells us a lot about how much play matters for them.”

The findings are likely to add to ongoing debate around calf feeding strategies and how best to balance productivity with animal welfare.