New research, published in Royal Society Biology Letters, has shown that calves’ ability to focus and learn is seriously impacted when their milk allowance is suddenly reduced, as well as them experiencing negative feelings of hunger.
Calves are often given less milk than they would want to drink – according to the study – and switched to sold feed abruptly during the early stages of weaning. Past work has shown that feeding restricted amounts of milk slows development, but little research has shown what calves feel and how hungry they are under feed restrictions.
The study assessed the effect of milk restriction on calf cognition in two experiments using a modified hole-board test. Researchers expected that the sudden reduction of milk allowance, in line with what would happen during weaning, would lead to calves being too hungry to focus on learning tasks.
To investigate this, the team used a test where calves have to remember the location of four milk-filled bottles among 15. By cutting the milk allowance, down from 12 litres to six, they explored whether this would negatively affect the capacity to remember where the milk bottles are, and whether this would disrupt the ability to re-learn after the location of the bottles was changed.
It found that cognitive performance dropped when the milk allowance was reduced by half, while the second experiment found that calves fed restricted quantities are slower to learn new rules.
Although not conclusive, the results were consistent with the negative experience of hunger. This type of study can help identify farm animal care practices that, when mitigated, could lead to improved welfare.
Dr Ben Lecorps, animal welfare lecturer at the Bristol Veterinary School, completed this study while working in the Animal Welfare Program at the University of British Columbia. As the corresponding author of the study, he stated: “Our results show that calves’ ability to focus is seriously reduced when their milk allowance is suddenly decreased suggesting that they most likely experience negative emotions associated with hunger.
“We need to know more about what calves feel if we want to change routine farm practices to improve their welfare. Although we may never be able to fully understand what a calf feels or thinks, this type of study gets us closer to this goal.
“Our results support the growing body of evidence that weaning from milk can induce hunger, particularly when animals are pushed to switch to solid feed (by decreasing milk allowances) abruptly. Our study also shows that it may be hard for calves to learn new tasks when they are experiencing high levels of hunger, which is concerning because it may slow down how fast they learn to feed from another source.”
The next step is to look at whether calves fed restricted quantities of milk show lower cognitive abilities compared to calves fed without restrictions. They expect those on restricted milk feeds will be slower to learn.
The researchers advise that farmers aim to mitigate the negative consequences associated with abrupt weaning, including feeding more milk at a younger age and gradually reducing the quantity at weaning.
A copy of the paper can be found here