What group behavior is being displayed by the cattle grouping together?

It is called a social behavior.

Explanation:

Group behavior is a term that expresses the manner of behavior among two or more interacting specie of organism to achieve a purpose. Various organisms show different group behaviors.

When cattle group together, they display a herding ungulates as the behavioral group. They come together to achieve a particular objective which could be for protection, survival, feeding etc. Thus forming a social group and interact among themselves.