Welfare of dairy cows in open-sided loose housing systems under temperate conditions—A review of potential challenges

Over recent decades, more open housing systems with partially uncovered functional barn areas have become increasingly common in both organic and conventional dairy farming in temperate climates. These open housings can enhance cow welfare by improving air quality, providing access to varying stimuli, including rain and sunlight, and allowing more space for social retreat. However, open housings may also expose cows to potential challenges from extreme weather, even in temperate climates. This review synthesizes English-language scientific literature from 2000 to 2023 on animal welfare challenges under less weather-protected housing conditions and evaluates various mitigation measures. A total of 83 relevant articles were identified via a search in the Web of Science and supplementary backward search, with an additional 54 articles included from previous and extended in-depth searches. In hot summer conditions, sun-exposed lying and feeding areas can increase heat stress and pose further welfare risks, including reduced lying times, lower feed intake, and more competition for drinkers. Shade, especially in high-use areas, is the most cost-effective solution, whereas additional measures, such as sprinklers or ventilation, use of heat-conducting bedding materials, increased number of drinkers, and adjusted feeding schedules to cooler times of the day, also support the cows in thermoregulation. In winter conditions, open housing systems pose fewer risks to cow thermal comfort, provided that animals have access to dry, wind-protected areas. However, in regions with more frequent rainfall, covered and dry lying areas help to prevent reduced lying times and claw diseases, udder soiling and infections. Potential risks from precipitation or cold temperatures in the walking and feeding area have been less studied yet. However, low temperatures combined with wind and precipitation can create icy floors, posing slip and injury risks, and precipitation penetrating roughage on the feed bunk might reduce feed quality and intake. However, future research on the extent of these risks and effects of possible mitigation measures would be relevant for the practical application.