Calves are often given much less milk than they would like to drink and abruptly transition to solid food at a young age during weaning. Previous research has shown that feeding calves limited amounts of milk slows down their development, but few studies have addressed how the calves feel and how hungry they are when subjected to feeding restrictions, according to a study cited by DairyGlobal.

Scientists from the Faculty of Land and Food Systems at the University of British Columbia and the Langford Veterinary School at the University of Bristol evaluated the effect of milk restrictions on calf cognition in 2 experiments using a modified hole-board test.

The team expected that a sudden reduction in milk allocation, mimicking what would happen during weaning, would be associated with calves being too hungry to focus on a learning task.

To investigate this, they used a test in which the calves had to remember the location of 4 bottles filled with milk among 15 bottles.

They explored whether a sudden milk restriction (reduced from 12 to 6 liters per day) would negatively affect the calves' ability to remember the location of the rewarded bottle and disrupt their ability to relearn after the bottles' locations were changed. In a new study, researchers found comparable benefits of waste milk compared to milk replacers.

Consistent with the idea that milk-fed calves experience hunger when the milk quantity is reduced, the study found that cognitive performance decreased when the milk allocation was halved. The research also showed that calves fed limited amounts of milk learned new rules more slowly.