Zero-grazing systems that keep dairy cows indoors year-round have expanded for productivity reasons, but raise significant welfare questions about natural behaviour deprivation.
Zero-grazing systems can provide good welfare in terms of nutrition and some health outcomes, but deprive cows of important behavioural opportunities including grazing, exposure to natural light and air, and the environmental variety of outdoor access. Research shows cows choose to go outdoors when given the choice even in mild adverse weather conditions, indicating a genuine preference beyond simple nutritional need. Cows in zero-grazing systems show more stereotypic behaviour and reduced positive affect indicators compared to grazed animals. The welfare case for maintaining outdoor access as a welfare requirement, rather than merely a production option, is supported by scientific evidence and consumer values.