BackgroundTie-stall housing of dairy cows is used extensively worldwide, despite of the welfare concerns regarding the restriction of voluntary movement and limitation of expression of the cows’ natural behaviour. The aim of this study was to compare the welfare quality of dairy cows kept in two types of tie-stall housing systems: with regular outdoor exercise and without access to exercise. In addition, the study investigated the relationship between different welfare measures of dairy cows kept in tie-stalls.Methods3,192 lactating cows were assessed using the Welfare Quality® assessment protocol for cattle in 80 commercial dairy farms, half of the farms providing outdoor access for the animals to exercise. The descriptive statistical indicators were determined for the assessed measures and for the welfare criteria and principle scores. The data obtained in the two housing types were compared and the correlation coefficients were calculated between the different welfare measures.ResultsThe significant differences found between the two housing systems for the majority of the animal based measures indicate the positive effect of exercise on the welfare of tethered cows. Many of the animal welfare parameters correlated with each other. For the farms allowing the cows’ turnout in a paddock, pasture or both, the mean scores for the welfare criteria and principles were higher than for the farms with permanent tethering of the cows, except the criteria absence of prolonged hunger and expression of social behaviours. The lowest scores were obtained for the criterion positive emotional state, in both housing systems. With regard to the overall classification, none of the farms were considered excellent. In the not classified category were only farms with all-year-round tethering of the animals and in the enhanced category only farms where the cows had outdoor access.ConclusionsThe welfare quality of the investigated dairy cows was significantly better in the tie-stall farms which allow exercise for cows (paddocks, pasture or both) than in those which do not. In the light of our results we consider that dairy cattle welfare is not necessarily poor in tie-stall housing systems, its quality depending on the management practices.