Polled Dorset

Polled Dorset
A photo of a ewe and lamb taken at the North Carolina State University Small Ruminant Unit.
Conservation status
Domesticated
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Family:	Bovidae
Subfamily:	Caprinae
Genus:	Ovis
Species:	O. aries
Binomial name
Ovis aries Linnaeus, 1758

The Polled Dorset is the breed of sheep developed for meat at the North Carolina State University Small Ruminant Unit in the early 1950s. The named refers to the fact that it is a hornless variation of the Dorset breed. Since its development, the Polled Dorset has outnumbered the Dorset sheep in number of registration. The Polled Dorset is often confused with the Australian Poll Dorset, which was not the result of a genetic mutation, but a result of the introduction of Corriedale and Ryeland blood into the Dorset breeding program.

History

NCSU 402 was the name given to the first true Polled Dorset sheep. It was named in accordance with the naming system that has been used at the NCSU Small Ruminant Unit since it started its breeding program. NCSU 402 occurred as a result of a genetic mutation between two Dorset sheep and was born polled, without horns. After research and testing were done to confirm that the Polled Dorset carried the same characteristics as the Horned Dorset and were able to propagate these traits, the new strain was accepted into U.S. registry in 1956. Polled Dorsets are ideal for commercial settings because they do not have horns that can get caught in fencing or cause damage when they butt. In 1949, four hornless lambs were sired from a horned Dorset on an NC State farm. Over the next five years, as part of their normal breeding program, those four ewes and the other ewes on the farm were bred to the horned Dorset. Eventually, a ewe gave birth to twin rams. NCSU 401 was a regular horned Dorset, but his brother, NCSU 402, was hornless. Thus, the Polled Dorset was born. Livestock scientists, the late Dr. Lemuel Goode and the late Sam Buchanan, are credited with identifying and developing the hornless sheep. The offspring of NCSU 402 were bought by other breeders and within twenty years, seventy percent of all registered Dorsets were polled. The success of the Polled Dorset made it concerned to be the second most popular sheep breed in the United States.

Conformation

Polled Dorsets are a medium sheep that are prolific, heavy milkers, long lived and produce hardy lambs with moderate growth and maturity that yield heavy muscled carcasses. Their fleece is very white, strong, close, free from dark fiber and have wool extending down the legs. When shorn, their fleece averages between five and nine pounds in ewes with a yield between fifty and seventy percent. The staple length ranges from 2.5 to 4 inches with a numeric count of 46's-58's. The fiber diameter will range from 33.0 to 27.0 microns. At maturity, ewes weigh between 150 and 200 pounds, with some weighing more at show condition. Rams at maturity weigh from 225 to 275 pounds. Dorsets are noted for their aseasonal breeding characteristics and are commonly used in crossbreeding to produce females for out-of-season breeding. They are one of the few breeds that have this characteristic. Multiple births are common and they work well in commercial operations. This includes programs that have rams that are specifically used to sire lambs for slaughter. These rams are known as terminal sires and they have genetics that are more suited for slaughter than breeding purposes.

Since the breed first became commercial, it has spread into Canada and become a major contributor to the commercial lamb industry. The breed adapts well to confinement and is readily used in accelerated crossbreeding programs. Polled dorsets do well under grass-based and feedlot conditions and on small holdings with intensive management because they are able to survive so well in confinement.

The Dorset's most remarkable trait is its ability to breed out of season, a quality not seen in most wooled breeds; properly managed Dorset ewes produce three lamb crops in just two years. Polled Dorsets are the most popular white-faced breed in North America, while the much less-common Dorset Horn remains in the Watch category ("Fewer than 2,500 annual registrations in the United States and estimated global population less than 10,000") of the American Rare Breeds Conservancy's Conservation Priority Watchlist.

Polled versus Horned Dorsets

The Dorset is an ancient breed that was most likely developed from horned sheep that lived in the valleys and pastures of southwestern England. Dorset Horn sheep were imported into the United States around 1860, although they did not appear in large numbers until the 1880s. Today, the Dorset is found in two varieties globally, Horned and Polled. The Polled Dorset variety was introduced in the early 1950s at North Carolina State University after a genetic mutation occurred in a purebred Dorset flock at the college. In the Horn variety, both ewes and rams have horns. Ewes’ horns are light and curve forward, while rams’ horns are heavy and spiral out as well as curve forward. The success of the Polled variety of Dorset sheep has almost completely obscured the Horned variety, so in response the horned Dorset has become a conservation interest. Horned Dorset are non-seasonal breeders but multiple births are not common with that breed. Polled Dorset commonly produce multiple births which makes them more of an asset to breeders. The only difference is in essence that one breed has a horn and the other doesn't. This is the main difference primarily between the two. Another aspect of the Polled Dorset is the color of these sheep which they are all white with long bodies and their faces are kind of wide compared to other breeds.

Continental Dorset Club

The very fist Polled Dorset group were registered by the Continental Dorset Club in 1956. Many of the available photographs of the Polled Dorset was taken by the Continental Dorset Club.