VOLKOV A. Improvement of the Duroc Pig Breed in Pure-Breeding and Efficiency of Using It in Crossing.

The dissertation is dedicated to questions of elaboration of methods of im-provement of the Duroc breed under new conditions using pigs of the Czech, American, English, and Danish selections, to creation of a stud with sows of im-proved reproductive qualities, and to determination of efficiency of using the breed in crossing with the White English breed. It has been found that a purposeful use of the Czech population for the ma-ternal basis and the American, English, and Danish populations for the paternal basis is an effective method of improving of the Duroc breed. On this basis, in conditions of the Open Joint Stock Company "Plemzavod Stepnoy", a Duroc pig stud of the Ukrainian selection excelling the best world analogues in production qualities of sows has been created.