Icelandic sheep are medium size. Ewes typically weigh 70 to 80 kg and rams 90-100 kg. They are fine boned with open face and legs and udders. The breed has both polled and horned individual of both sexes but it is primarily horned. Icelandic sheep are not particularly tall but broad and have an excellent conformation as a meat breed. They are seasonal breeders, the ewes start to come into heat around early November, lasting through April. By early October the mature rams develop a distinct odour which stimulates breeding activity in the ewes. The odour remains with the rams through the breeding season. This smell will also have an adverse effect on meat quality if mature rams are slaughtered during that period. Occasionally the Icelandic sheep will breed out of season but that has not been encouraged in Iceland. The fecundity in the ewes is excellent and the mature rams are very efficient breeders. Lambing rate is a approximately 170-180%, with increases possible through more intensive management. They are early maturing and the ewes can easily lamb at 12 months of age. Ram lambs can start breeding around seven months old. Life expectancy is long, healthy ewes commonly lambing until they are 12 to 14 years old in Iceland. The wool is dual coated and comes in many natural colours, even though the white colour is most common.