With knowledge of the reproductive surplus of females, and knowledge of the fraction of the total population that is currently made up of cross-breeds, the fraction of pure-breeds that can be utilized to produce F1s without further decreasing the population size of the pure breed can be calculated. As an example, if there is a 20 percent reproductive surplus of females and the current population is composed of 50 percent pure-breeds and 50 percent cross-breeds (includes any pure-bred females that are currently being used for cross-breeding), the population could move towards a composition of slightly more than 50 percent pure-breeds producing pure- breeds, slightly more than 20 percent pure-breeds producing F1s, and slightly less than 30 percent F1 females, without any further reduction in the size of the pure-bred population that is producing pure-breeds. These values assume that none of the females produced by the F1 females are retained as breeding females; in reality, this would probably never occur.