Inbreeding is basically the mating of animals that are related. Within the pedigree of the mated sire and dam, one or more animals will be in common; resulting in progeny with a certain level of inbreeding. The level of inbreeding will depend on the relationship between the two mated animals. The closer the relationship, the greater the level of inbreeding that will occur in the resulting progeny.
Linebreeding is the deliberate mating of closely related animals with the perceived objective to concentrate desirable characteristics of the progeny and to breed consistency”.
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There is no magic level that is considered an acceptable level of inbreeding within a breeding program, with the goal in most breeding programs being to manage inbreeding rather than totally avoid it. Breeding programs that simply avoid inbreeding without considering the genetic merit of the animals used within the mating program are not likely to be economically sustainable in the long term