High animal density impairs feed intake, daily weight gain and feed conversion ratio in growing cattle. Furthermore, in crowded circumstances animals are dirtier, and tail tip lesions and behavioural disorders are more common than in higher space allowances. Low space allowance especially disturbs resting behaviour and increases aggressive behaviour. In groups of 30–60, animals may not grow as well as in groups with fewer animals. Furthermore, as group size increases, recognition of other animals becomes more diffi cult, which may result in increased aggression between the animals. Accordingly, large cattle groups are feasible only when there is suffi cient space for the animals to form smaller subgroups. The floor material of the pen has little effect on the production of growing cattle. On concrete slatted floors, however, animals have more diffi culties in lying down and getting up, and have more foot problems and tail tip lesions than on bedding. Foot problems are common also on sloped fl oors. According to preference studies, straw is the most and concrete slats the least preferred fl oor type. In conclusion, in order to improve the welfare of growing cattle, the animals should have suffi cient amount of space, group sizes should be adjusted to space allowance and the surface of the lying area should be soft.