Calves fed more milk prioritise play over feeding in a hole-board test.

Dairy calves are typically feed-restricted. Depending on its severity, hunger can improve or impair animals’ cognitive abilities, but the effect of chronic feed restriction on calf cognition remains underexplored. We used a spatial foraging task (hole-board test) to assess whether chronic feed restriction impairs cognitive performance in dairy calves provided 6 L/day of milk (restricted) compared to calves provided up to 12 L/day (enhanced). Calves had to recall 4 milk reward locations among 15 possibilities; locations remained constant for 14 trials (initial learning), and were then changed and kept constant for 6 trials (re-learning). We measured calves’ ability to remember locations already visited within trials (working and general working memory) and recall reward locations between trials (reference memory). We also measured play behaviour to explore trade-offs between foraging and playing in the testing arena (larger than calves’ home-pen). Restricted calves had better working and reference memory, shorter latencies to reach the first bucket, and completed trials faster, indicating higher food motivation. Enhanced calves were less motivated to engage in the test but played more than restricted ones. This highlights how hunger can shift priorities to foraging. Future research should explore trade-offs between important behaviours like play and feeding to understand the value calves place on different activities.