Group housing is a natural and economic way of raising calves. One major disadvan-tage of group housing calves is the occurrence of cross-sucking as an abnormal behaviour. The main objective of our study on organic calf housing was the reduction of cross-sucking related to milk feeding. A new feeding stall with automatic gates was attached to an automatic teat feeder. One gate opened to an enriched area immedi-ately when the calves had finished their milk meal. In this zone calves could use rub-ber teats or a hay net (treatment optimized). The design for the control group used a simple feeding stall without attached enriched zone. 168 female calves (German Holstein) from one origin (herd) were randomly assigned to 14 groups with 12 calves each. Thus, each treatment could be repeated seven times. Two groups were used for preliminary testing of housing and technique. Calves were fed whole milk, according to EU-organic-farming-guidelines. The behaviour of calves was observed directly for 20 minutes following milk intake. In addition, 24 hour video observation completed the behavioural monitoring. The videos were analyzed with the continuous sampling method; statistical analysis was done with the SAS statistical software package and non-parametric procedures. As one result, cross-sucking of calves decreased signifi-cantly in the optimized housing treatment compared to the control treatment: cross-sucking behaviour occurred for 12% of the calves of the optimized treatment vs. 60% cross-sucking calves in the control treatment. Regarding the intensity of cross-sucking, the control group showed 200 cross-sucking bouts per 100 calves and meal, in comparison with a frequency of 16 bouts of the optimized treatment. Our study supports the thesis, that design of housing and environment could be used to reduce cross-sucking of group housed calves. However, future research should be done to evaluate interactions between feeding techniques, environment and physiological processes related to cross-sucking behaviour of calves
