the start is similar to backcrossing. Females of breed A are crossed to males of breed B. Their female offspring (F1) are (back) crossed with a male of breed B. Their female offspring (F2) are crossed with a male of breed A. Their female offspring (F3) are crossed with a male of breed B etc. Alternately, in each generation males of breed A and breed B are used and crossbred females in all generations can be used to produce replacements. In such a cross a part (2/3 compared to a pure-breed cross) of the heterosis effect can still be exploited. The pure breeds still need to be maintained with a breeding program, but other breeders can do this. Below the two-way rotation cross in cattle is illustrated:
