Date of this Version
Although data are scarce, it is clear that grouping strategy can have a significant impact on the feeding behavior and feed intake of dairy cattle. Feed intake is controlled by ruminoreticular fill and physiological mechanisms, but grouping is a component of the cow’s feeding environment that can modulate intake as a result of its impact on cow comfort, competition for feed and other resources, and herd health. Social dominance and competition for feed impact feeding behavior and proper grouping strategy will minimize the negative impact of excessive competition on intake and enhance beneficial effects of group feeding such as social facilitation. Primiparous cows benefit from separate grouping from older animals by increased intake and productivity. Bunk space, accessibility of feed, and type of feeding system must be considered when determining the optimal group size. There appears to be no problem with large (>200 cows) groups of cows per se, but management decisions such as overcrowding with insufficient head gates or manger space play a role in determining cow well-being and feeding behavior. Research with group sizes larger than 400 cows needs to evaluate productivity, feeding and other behavior, and animal well-being. Significant overcrowding appears to reduce feeding activity, alter resting behavior, and decrease rumination activity. Negative social consequences of moving cows between groups last 3 to 7 d. Although the effect of grouping on feeding behavior remains largely unquantitated at this point, the effect is potentially large and requires further research to describe the impact of cow dynamics within a group on feed intake.