Willis (1989) defines INBREEDING as the mating of animals "more closely related to one another than the average relationship within the breed." From the introductory table we can see that these involve brother/sister or parent/child breeding.
With all the negative connotations associated with inbreeding why discuss it as a viable breeders tool?
It is true inbreeding can create horrific genetic mistakes or it can be the best and fastest way to improve and standardize a line (set traits). IN the first sense it is a useful genetic tool to reveal hidden recessive genetic problems in your line by doubling up on them and making them express themselves (as it were LOL). Note this is a tool used to reveal hidden defects and these defectives should be culled from the breeding pool. In the second sense when your line is heterotrophic for beneficial traits you can do inbreeding to make them homozygous (set the trait). Note it must be a tremendously important trait or preferably numerous traits you are trying to set within your line to consider inbreeding as the best method to set the trait. So here inbreedings are done to verify the superiority of a particular strain or to check for recessive problems. Any weaknesses, faults, deformities, etc. are likely to show up. If a truly superior line or strain has been developed, containing only desirable qualities, these desirable qualities will be seen in the resulting offspring.