Inbreeding is most always used to keep the desirable traits in every breed. The 100000s of chicks that hatcheries breed and sell for egg laying or fryers are well inbred for the best layers obtainable and/or for quick growing birds for meat. The flocks they come from are flock bred and no individual records of various breeding birds. It is possible to use these birds for breeding for YEARS, with new stock introduced, partially, and the "new" stock is not a guess, but well identified closely bred birds to continue their successes without a skip in their usefulness. They could not afford to "guess" what next year's chicks will produce when mature. The crosses that produce those egg layers, are indeed related and not 'guesses. Purebred chickens for Show birds, bred to a Standard, are also inbred (line bred is the preferred term), as, again, the best is kept dominant, poor recessives (few) are culled from breeding pens. One of my best and still productive hens is inbred, direct descendant from a hen bred in 1992, and hope for a daughter to keep the line going. Would never breed her to an unrelated male and lose the years of selection that she exhibits.
if you are afraid of inbreeding, obtain a near relative for future breeding, and keeping the best, will make your birds just what you want in each new generation. (mine are over 20 years of line breeding, do not ever need to purchase new bloodlines-- yet--but will, if the strength of the birds is diminished.)
Edited by JeanR - 1/12/16 at 1:15pm