14.7.1.1 The outline of an introgression scheme (2024)

The second and third method of expansion maybe hampered by large genetic differences between breeds in the breeding goal traits (level and combination of traits).

The appropriate crossbreeding scheme to be applied has the structure of  the introgression scheme:

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(Source: Het fokken van rashonden. Omgaan met verwantschap en inteelt, 2012. Kor Oldenbroek en Jack Windig. rvb_hetfokkenvanrashonden_20121029_01.pdf (houdenvanhonden.nl)

Animals from a donor breed are only used to produce the F₁. In the F₁ and F₂ the animals are as much as possible selected for the breeding goal traits at stake in the original pure recipient breed. It might be wise that the breeding organization keeps full control over the use of the F₁ and F₂ animals. If the traits of these animals appear to be far outside the breeding goal of the recipient breed, then it should always be possible to terminate the introgression of their genes in the recipient breed.

This crossbreeding method is only recommended when the rate of inbreeding in the population is that high that genetic defects are a real threat for a “melt down” of the population. In a few dog breeds the introgression is considered and in the past in the Dutch Gelderlander horse breed introgression has taken place a few times.