Genetic Consequences of Crossbreeding

Abstract

CROSSBREEDING involves the mating of two or more breeds. In most species of domestic livestock, crossbreeding has some desirable consequences, especially in the pro- duction of market stock. These consequences are the production of heterosis, the opportu- nity to incorporate desirable genetic material quickly, and the chance to combine several desirable traits into a market animal. The consequences of crossbreeding depend on gene frequency differences among the breeds with the resulting increase of heterozygotes in the cross and the degree of dominance. For the crossbreeding to be utilized commer- cially in a class of livestock, there either must be a source of distinct genetic groups or the production of such groups must be econom- ically possible, and the resulting crosses must have a distinct economic advantage over con- ventional market stock. Crossbreeding produces some desirable consequences. They are the production of heterosis, the opportunity to incorporate desirable genetic material quickly, and the chance to combine several desirable traits intoa market animal. The primary factor involved in each consequence is genetic divergence as measured by gene frequency difference among the groups. The degree of dominance is important in the production of heterosis and combining several desirable traits.