Breed of large dairy cattle that originated in northern Holland and Friesland. Its chief characteristics are its large size and black-and-white-spotted markings, sharply defined rather than blended. Probably selected for their dairy qualities c. 2,000 years ago, they have long been distributed over the fertile lowlands of continental Europe. In the U.S., Holsteins outnumber all other dairy breeds and produce 90% of the milk supply. Their milk has a relatively low butterfat content.