There are many different sheep breeds. Breed selection is based upon personal preference, regional marketing opportunities, and sheep production goals. The most important traits for commercial production in the northeastern United States are aseasonality and prolificacy. Wool color, fineness and staple length are important to many producers.
Some producers utilize milking breeds for specialty cheese production.
Sheep with large potential mature size gain more muscle and less fat to a given weight than sheep with small potential mature size. Therefore, larger mature size sheep are more efficient, gain faster, and produce leaner carcasses. A disadvantage of large mature size sheep is the higher cost of maintaining a breeding flock. Sheep producers can take advantage of breed differences in mature size by using a terminal sire program. The commercial flock at Cornell is composed of Finnsheep x Dorset ewes bred to Suffolk rams.