In breeding

[alforddm]

Why is breeding parent to offspring generally considered more acceptable than breeding siblings? According to this https://en.wikipedia.org/wiki/Coefficie ... lationship the inbreeding coefficient is the same.


LOL I think I may have though of the reason. If you trying to fix a trait you have a higher chance of fixing that trait by breeding back to the parent with the desirable trait than breeding to a sibling?

 

[Celice]

you can breed brother and sister just fine. It would be wise to breed the resulting kits out and then back in if you are looking for traits that you want.

 

[Zass]

I think the brother/sister prohibition is mostly folklore.

As for getting good traits, it is a bit more touch and go than line breeding.

For example, you may know for sure a parent has a desired recessive trait, but, only about 50% of the offspring will inherit it.

Breeding back to the parent is a more sure way to turn up who has that recessive than breeding siblings together in hopes of finding two that are both carrying it.

 

[akane]

Breeding siblings is not the same as breeding to parents. Say we call one parent blue and one red. Your offspring have 50% blue and 50% red. A 50/50 bred to a 100% blue does not always give you the same thing as crossing 50/50 blue and red. They have the same amount of odds of different genetic material but you don't know the odds of which original parent it came from. A 50/50 offspring to the blue parent can't give you lower than 50% blue. If both siblings pass on more of the genes they got from parent blue you may have a mostly genetically blue offspring like you would get crossing back to the blue parent. You could also end up with a mostly red 3rd generation or anything in between. You don't know. You quickly lose track of how much genetic material from blue or red is in your current generation. If you keep breeding back to a parent though you keep repeating the addition of genetic material from that parent which can show you what is good and what is bad in that particular group of genes faster. At first this doesn't matter because you don't know your new rabbits that well but it makes it easier to keep track of where things originated. When you start to know the bloodlines of your rabbits better you can then determine what else is likely to give a bad or better result when looking at your current offspring. If a trait keeps showing up in rabbits that tend to have been bred back to red followed by offspring likely to carry the most red you know it at least has a high chance of coming from the original red parent and you know which other rabbits have a higher or lesser chance of it. If you kept breeding siblings you would soon have no idea how much of blue or red is in any given generation. You could put some odds to it but you don't truly know how red or how blue they are.

Rabbits breed fast enough, change fast enough from gen to gen, and withstand inbreeding well enough that for the most part you can ignore that detail of where variations in genetic material came from. Try it with something like horses though. It will take 3 years to really get a feel for what you created with that pair and then it will be another 2 years minimum to breed the next generation. You need to ID fast that this is a trait this stallion tends to throw and this is a trait this mare tends to throw and decide a breeding program that reduces the times you inbreed as much as possible. You really have to aim for bringing in known traits with few culls. Those situations it becomes more important to keep track. Some seem to do it intuitively and some keep very very detailed records of everything.