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Why do breeders use crossbreeding when inbreeding depression appears in a population?

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Red Poll cows — Animal breeding Red Poll cow and calf.

Breeders use crossbreeding to combat inbreeding depression because it introduces more diverse genes into a population.1

Inbreeding is often used to concentrate desirable traits, but it narrows the genetic base and can lead to detrimental effects, including reduced fertility, slower growth rates, increased susceptibility to disease, and higher mortality. When these negative consequences become evident, crossbreeding serves as a necessary method to restore genetic diversity.1

Furthermore, breeders may exploit heterosis—the phenomenon where hybrid offspring exhibit increased vigor, such as improved size, growth rate, and fertility, compared to their parents. By mating two different lines, breeders can leverage this hybrid vigor to counteract the decline in performance associated with inbreeding.21