EFFECT ON SOCIAL-ORGANIZATION AND MILK-PRODUCTION OF MINOR GROUP ALTERATIONS IN DAIRY-CATTLE

Two groups of fifteen and twelve cows were maintained under identical conditions of management. The two most dominant cows from the group of fifteen cows were transferred to the group of twelve. Both cows were lactating. They were returned two weeks later. After a further four weeks, the two most subordinate cows from the group of fifteen cows, both also lactating, were transferred to the other group and returned two weeks later. On both occasions, the establishment of the new cows within the hierarchy was completed within twenty-four hours. This establishment was accompanied by a doubling of aggressive activity which was more prolonged following the introduction of the two most dominant animals. During both moves, the relationships between all the cows remained unchanged. The increase in aggression had no effect on milk yield. © 1979.