Dairy cattle
Dairy cattle housing systems vary greatly throughout the world depending on the climate, dairy size, and feeding strategies. Housing must provide access to feed, water and protection from relevant environmental conditions. One issue for humanely housing cattle is temperature extremes. Heat stress can decrease fertility and milk production in cattle. Providing shade is a very common method for reducing heat stress. Barns may also incorporate fans or tunnel ventilation into the architecture of the barn structure. Overly cold conditions, while rarely deadly for cattle, cause increases in maintenance energy requirements and thus increased feed intake and decreased milk production. During the winter months, where temperatures are low enough, dairy cattle are often kept inside barns which are warmed by their collective body heat.