A total of 165 group-fed bulls of the Swedish Red and White breed were used to investigate differences in weight gain, feed intake, feed conversion, carcass traits and health when housed either in an insulated building with slatted floors in the pens or in an uninsulated building with partly deep-littered pens. The total pen area was 1.5–2.3 m2/bull in the insulated building and 3.6–5.8 m2/bull in the uninsulated building. The animals were fed a restricted amount of concentrate which was calculated to cover 50% of the energy requirement and grass silagead libitum.They were slaughtered at about 470 kg live weight.