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in animal breeding, a male (bull, stallion, boar, ram) used for obtaining offspring. Artificial insemination enables a single valuable sire to produce hundreds or thousands of offspring a year. For pedigree use, sires are selected from highly productive fertile parents and are evaluated on the basis of their ancestors; they must have a proper conformation, good health, and resistance to disease. In the process of pedigree use they are evaluated on the basis of their progeny. A sire whose offspring excels its parents in productivity and pedigree qualities is considered an improver. Especially valuable are sires that consistently transmit valuable properties to their offspring. In the USSR the best sires are kept at centers where pedigree work is conducted and artificial insemination is performed. The semen of sires is exchanged between countries.