Bonney-King and Lindner are graduate students and Miller-Cushon is an associate professor at the University of Florida.
Common situations, such as introduction to new social groups and exposure to higher stocking densities, can result in more aggressive social interactions. When stocking density is high, competition for feed and stall access will be greater, and some cows will be discouraged from feeding or visiting stalls as often. A cow’s overall welfare and productivity will depend in part on how it responds to these environmental contingencies, including routine social encounters and management changes.
In recent years, there has been growing adoption of social housing for dairy calves, which accommodates natural social behaviors such as grooming and play and provides exposure to a range of social interactions at a younger age. Previous research indicates that social housing enables the earlier development of important social skills. When compared to individually reared calves, socially housed calves interact with unfamiliar calves more readily and are more successful when faced with competition for access to feed. More generally, socially housed calves are less fearful and avoidant of novelty.
Quicker adaptation
In recent research published in the Journal of Dairy Science, we asked how socially housing dairy calves might shape longer term behavior. Dairy calves were raised either in individual pens or pair pens during the preweaning period, but they were otherwise managed identically and provided 8 liters of milk per day. Following weaning at 8 weeks of age, calves from both housing treatments were raised together in groups on pasture. Nearly two years later, when the heifers were pregnant and within 30 days of their expected calving dates, we observed how they behaved when introduced to a freestall barn for the first time.
Perhaps similar to the stress a human might feel on the first day of school, this event involved the simultaneous introduction to an unfamiliar environment and a new social group consisting of both other naïve heifers and multiparous cows. Previous research has described disrupted rest and feeding time as common behavioral responses to this housing transition as heifers learn to enter freestalls and access the feedbunk and experience aggression from other animals, especially in mixed parity groups.
Our findings suggested that early social housing may have surprisingly persistent effects on behavior. During the day following introduction to the freestall barn, we found that heifers previously raised in pairs spent more time eating than those reared individually. Those heifers were also heavier, although greater body weight was accounted for statistically and did not explain the observed treatment differences. We also found that, although lying time was not affected by calf social housing, previously pair-housed heifers spent less time in the stall and more time walking around the barn. These findings may suggest that the heifers previously raised in pairs as calves were quicker to explore their environment and less affected by this housing transition.
Handling competition
Higher stocking density creates an added challenge, particularly for naïve heifers, raising the likelihood of aggression and displacements at the feedbunk and in stalls. In our experiment, stocking density was variable depending on farm management, so we recorded it to consider how it may affect behavior. We found that lower stocking density appeared to level the playing field, as social housing had less of an effect on how heifers behaved during the stressful transition to the freestall when stocking density was low. However, when stocking density was high (more animals than stalls in the pen), previously individually housed heifers visited the feedbunk less frequently, which resulted in less total feeding time. They also had less frequent but longer stall visits, so they spent more time in the stall.
This pattern of behavior where a resource is accessed less frequently is a typical response to competition, or a high “cost” of accessing that resource. Our findings suggest that when stocking density was high, previously individually housed heifers perceived or experienced greater competitive pressure for access to the stall and the feedbunk. In support of this idea, we found that previously individually housed heifers were also more likely to be displaced from a stall than heifers raised in pair housing. Social housing may, therefore, produce cows that cope with social pressure and competition more easily.
Many, varied benefits
These findings may be explained by many of the short-term effects of social housing that have been previously observed in calves: more social interaction, improved competitive ability, and reduced fearfulness when faced with novelty. In addition, socially housed calves are often heavier, and some studies like ours have suggested long-term growth advantages attributed to social housing. The combination of improved social ability and greater body size provides an advantage, with respect to feed access and other competitive interactions.
Other behavioral differences could also be at play — personality traits such as sociability and fearfulness may be shaped by early experience and subsequently affect responses to events in later life. More research is needed to understand how social housing for calves may shape behavioral responses in other contexts and over a longer time period. In addition, we await more insight into how social housing may affect other outcomes of welfare and economic significance in dairy cows, including health and milk production.
It appears that social housing may influence how dairy cows respond to stressful events and social pressure. Calf social housing may therefore provide some compelling long-term benefits: raising confident cows!
