Dairy calves are typically separated from their mothers and housed by themselves for the first 6 to 8 weeks of life. A new study, published by in PLoS One by researchers in UBC’s Animal Welfare Program, shows that calves raised individually have a harder time learning compared to calves socially housed with another calf.
Calves were initially taught a simple task: when they entered a test pen they could approach a black bottle and receive milk, or approach a white bottle and receive no reward. All calves were quick learners and soon learned to approach only the black bottle. At this point the researchers switched the rules, such that visits to the white bottle were now rewarded with milk and visits to the black bottle were unrewarded. Post doctoral researcher Dr. Becky Meagher explains what happened next: “Both the individually housed and pair-housed calves initially struggled with the new task, but after a few training sessions the pair housed calves began approaching the correct bottle while the individually housed calves more often persisted with the old (and now incorrect) strategy. This type of learning deficit has also been found in laboratory animals that are housed individually.”
The simplest form of learning is habituation; typically animals respond strongly to novel stimulus but over time show a reduced response. When the individually housed and pair-housed calves were first exposed to novel object (in this case a red rubber ball) they both showed interest, but after multiple exposures the individually housed calves kept investigating the object while the paired calves showed the expected habituation response and tended to ignore the ball.
This study provides the first evidence that the common practice of individual housing causes cognitive deficits in calves, but should this matter to dairy farmers? “Learning difficulties, including trouble adjusting to changes in routine and environment, are likely to cause problems for farmers as well as the animals” explains UBC Professor Dan Weary. “For example, later in life, calves are kept in groups, and must learn to adjust to new surroundings, group mates, new types of feed, etc., and other research has shown that individually housed calves struggle with this transition, often eating less and losing weight relative to calves that were previously pair housed. We recommend that farmers use some form of social housing for their calves during the milk feeding period.”
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