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Breeding back to mom??
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<blockquote data-quote="ArmyDoc" data-source="post: 482099" data-attributes="member: 6832"><p>The vets advice doesn't make any sense to me either. An inbred / linebred animal is by definition one that statistically will have a higher percentage homozygous genes than that of the general population. If this inidvidual does not have any problems, the breeding it to another animal from the general population will result in it's offspring having a lower percentage of homozygous genes. </p><p></p><p>You can demonstrate this yourself using a program like pedigree viewer. If you create a line bred pedigree, the Inbreeding Coefficient (IC) continues to rise, but if you out cross to an unrelated individual, that ofsprings IC drops to zero again. </p><p></p><p>I think the problem is more likely to happen the longer you continue the inbreeding/linebreeding process. This has been done with laboratory rats. Breeding sire to daughter, to grand daughter to great grand daughter and so on. What happens is that over time vigor and fertility drops. Generally after 8 or 9 generations the number of offspring in each litter drops to the point where the line can't be continued, and dies out. </p><p></p><p>All of this merely the flip side of hybrid vigor. Just as you get hybrid vigor by outcrossing, you get a gradual decrease in "vigor" by inbreeding. The difference is that the decrease in vigor is gradual with inbreeding - because the IC changes slowly with inbreeding, but rapidly with outcrossing, I presume. But because the decrease in vigor is slow, you may be able to compensate for it by sellection and rigorus culling.</p></blockquote><p></p>
[QUOTE="ArmyDoc, post: 482099, member: 6832"] The vets advice doesn't make any sense to me either. An inbred / linebred animal is by definition one that statistically will have a higher percentage homozygous genes than that of the general population. If this inidvidual does not have any problems, the breeding it to another animal from the general population will result in it's offspring having a lower percentage of homozygous genes. You can demonstrate this yourself using a program like pedigree viewer. If you create a line bred pedigree, the Inbreeding Coefficient (IC) continues to rise, but if you out cross to an unrelated individual, that ofsprings IC drops to zero again. I think the problem is more likely to happen the longer you continue the inbreeding/linebreeding process. This has been done with laboratory rats. Breeding sire to daughter, to grand daughter to great grand daughter and so on. What happens is that over time vigor and fertility drops. Generally after 8 or 9 generations the number of offspring in each litter drops to the point where the line can't be continued, and dies out. All of this merely the flip side of hybrid vigor. Just as you get hybrid vigor by outcrossing, you get a gradual decrease in "vigor" by inbreeding. The difference is that the decrease in vigor is gradual with inbreeding - because the IC changes slowly with inbreeding, but rapidly with outcrossing, I presume. But because the decrease in vigor is slow, you may be able to compensate for it by sellection and rigorus culling. [/QUOTE]
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