Cows are social
In the wild, cows live in groups of 10-20 individuals, consisting of a bull, cows, heifers and calves. Aurochs gathered in large groups during winter while they spend the summers in smaller groups. Cows eat, rest and drink at the same time as the rest of their group. This is challenged in barns with automatic milking systems where the cows have individual access to the robot throughout the day. In these systems the cows are fed at a higher frequency to make the cows seek the feeder and the robot more often. This is also advantageous in large groups because lower ranking cows have better access to the resources in the less busy periods of the day. There is a complicated hierarchy amongst the cows that is affected by factors such as age and size, and whether or not they have horns. A cow can be dominant to one cow and submissive to another cow in the group. Stable groups that work well require good housing systems, where cows that have to be moved from one group to another, are always moved in smaller groups with familiar cows. Cows that move together will settle down easier in a new facility with new cows. An appropriate design of the housing system makes it easier to maintain the desired division of groups and to move the animals around in the system. A stable hierarchy ensures a calm atmosphere in the group and a lower level of aggression once the hierarchy is established. The design of the barn must take into consideration that animals will pass each other in passageways. Extra stalls and adequate space at the feeder can lower the level of aggression significantly. When calving the cow will leave the group if the pen or the paddock allows it. The cow prefers to find a place where she is in hiding but still has good view of the group. It is important to take this into consideration in the design of the calving pen to make sure that calvings and the subsequent start of lactation is as stress free as possible.