The Jacob sheep is indeed a unique breed. Slight of build, with the narrow, lean carcass typical of some of the ancient British breeds, they are immediately noticeable due to their black and white fleeces and prominent horns. Both males and females are horned, sporting two, four and occasionally six horns. Two-horned rams develop the more familiar classic double curl. Horns on the ewe are always shorter and more delicate than the rams' horns.
The Jacob fleece, which is properly described as white with black spots, is prized by hand spinners and weavers. The white and the black wool, which may fade at the tips to dark brown, may be blended to various shades of greys. Ideally, the animal should be 40% black and 60% white, with certain characteristic patterns. The legs should be predominantly white, with black hooves and black knees and hocks desirable. The desired Jacob face is frequently referred to as "badger faced', with black cheeks and muzzle, but a white blaze down the front of the face. The nose should be black as well as the horns and ears.
The Jacob is an old, unimproved breed. As a result, it is slight in build, with ewes averaging only about 100 to 120 pounds. Typical fleeces will weigh only three or four pounds, and may vary quite a bit in coloring, crimp, and fineness. They bear one or two lambs in the spring only, and lambing is typically very easy for these sheep. Horn growth begins immediately and the ram lambs will be born with horn buds already poking through the wool.