the presence in animals of the characteristics typical for their particular breed. The offspring of animals belonging to the same breed are considered purebred. When animals of different breeds are mated, they produce crossbreeds of differing degrees of breed purity. The first generation of crossbreeds are considered “semipurebreds,” that is, the proportion of hereditary characteristics from each of the parent breeds in such crossbreeds is equal.
Mating a first-generation crossbreed with a purebred animal of one of the parent breeds produces a second-generation crossbreed whose breed purity is three-fourths of one parent breed and one-fourth of the other. Mating a first-generation crossbreed with a purebred animal of a third breed will produce composite crossbred progeny whose breed purity is one-half the blood of the third breed and one-fourth of each of the other two breeds. If crossbreeds are mated with purebred animals of one of the parent breeds for several generations, their breed purity increases with each generation, gradually approaching purebred. Outstanding crossbreeds of the fourth or fifth generation are considered purebreds.
Representations of breed purity by fractions are used as guidelines in breeding work.
REFERENCEBorisenko, E. Ia. Razvedenie sel’skokhoziaistvennykh zhivotnykh, 4th ed. Moscow, 1967.
A. P. BEGUCHEV