The collective noun for cows is "herd." Other words that are used include "dairy," "drove," "pack" and "team," though some of these are more common in other English-speaking countries outside of the U.S.
Collective nouns for groups of animals and insects widely vary. For example, gnats exist in clouds, birds and sheep move in flocks, camels wander deserts in caravans, dogs and wolves hunt in packs, fish swim in schools and owls form a parliament. In some cases, two different words can be applied to a group of animals. For example, multiple cats form either a clowder or a clutter.