This is particularly true for ewes with newborn lambs. The compound also seems to reduce the fertility of ewes and heifers. Both rams and ewes are polled. Both rams and ewes are horned. Zwartbles rams and ewes cross well with other breeds. Male mouflon are known as rams and the females as ewes or wild ewes. Rams on average weigh and ewes at maturity. It normally carries 100,000 breeding ewes and about 8,000 cattle. Bighorn ewes have a six-month gestation. Ewes typically weigh between , and rams between . Don also has a sheep farm, on which he keeps 500 ewes. Mature rams (males) weigh about , while ewes (females) weigh about . Physically, rams and ewes are remarkably similar. Rams battle to determine the dominant animal, which then gains possession of the ewes.