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

Dairy calves are typically feed-restricted and are frequently hungry. 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 6L/day of milk (restricted) compared to calves provided up to 12L/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 measured play behaviour to explore trade-offs between foraging and playing in a space larger than calves’ home-pen. Restricted calves had better reference and working memory, shorter latencies to reach the first bucket, and completed trials faster, indicating high motivation to find food. Enhanced calves played more than restricted ones, highlighting the importance of play behaviour when calves are not feed-restricted and how hunger shifts priorities to foraging. Future research should continue to explore links between feed restriction and cognition.