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Seedstock breeders of poultry and of many plants; such as corn, may use static systems of mating that produce sufficient hybrids for complete use of heterosis in commerical production. Use of heterosis in these species can be maximized because only a small proportion of the total population is required for seedstock production. Complete use of heterosis is more difficult in cattle because of their relatively low reproductive rate and long generation interval, which overlaps from one year to the next. However, this difficulty does not preclude the use of a high level of heterosis in commercial beef production. Systems of crossbreeding can be used that maintain significant levels of heterosis from one generation to the next. Crossbreeding systems can also provide for use of additive genetic variation between breeds to combine and match characteristics of breeds with feed and other production resources and with market requirements.