From weaning to mating the indoor sow can be housed in one of three ways; individually confined in a stall or by a tether, mixed in groups of 2 to 15 sows or moved into a dynamic group, or introduced into a boar pen on the day of weaning for 2-4 days and then individually confined. Each of these systems has its advantages and disadvantages and they may be dictated to some extent by the welfare regulations of your country. For example in the UK, stalls and tethers are to be banned in 1999 and therefore loose housing systems will have to be used. Under such circumstances groups of sows on the day of weaning are best mixed into a large yard with a minimum of 2.7 sq.m. per sow together with a large old boar. The boar's presence will have two effects, one of stimulating oestrus and the other of reducing any fighting that is likely to occur. The grouped sows should be fed ad lib from weaning to mating from at least two well separated feeders. The boar should be removed from the group on day 4 and where possible, sows should be confined to stalls over the next 48 hours during the period of oestrus. This is a welfare friendly act because it reduces riding and stress as sows come into heat. Confined sows should remain in their stalls until 21 days post mating. Loosed housed sows should be returned to the group as soon as mating is completed and a boar re-introduced until at least 21 days post mating. It is very important that the floor surfaces are dry and non slippery, the concrete not worn and there are no protrusions from sharp aggregate, especially in the mating pen. Slatted floors can be used for housing sows in the immediate post weaning period but not the mating or boar pen because they produce lameness and discomfort at mating. Remember the weight on the sows hind legs and feet is multiplied three fold during mating and slats increase the risk of damage.