 Summertime heat can be a challenge for pastured cattle. Kansas State University Extension veterinarian A.J. Tarpoff. Cattle don't lay down as much, especially whenever they get heat stress. They're trying to increase airflow. Unfortunately, that might lead to bunching, where groups of cattle, even in a pasture, will bunch up together. They're trying to get increased airflow, but they end up using each other as shade, which is kind of counterproductive.