brother/sister pairing

[rabbitgirl]

Two of my kits went to the same home at 9 wks.and were "accidentally" mated at 3 1/2 months. They are siblings.

How does a brother/sister pairing work out as far as health goes? Ithought linebreeding was usually mother/fathertoson/daughter. What are the genetic possibilities?

They are healthy purebreds, the product of an outcross, if that makes any difference.

And any suggestions for care of a young mom? The kits (if she's pregnant) are due the week after next.

Thanks!

Rose

 

[m.e.]

This comes up on the CatForum a lot, so I'll post one of their comments:

"The thing with inbreeding is the weaknesses of the cats aredoubled, but the strengths are doubled too. So if the cats have ahereditary predisposition to have deformities and a long life span forexample, its twice as likely the kittens will have deformities but livea long time (so long as the deformities are not the kind that causepremature death).

The real problems with inbreeding happen when it happens again andagain and again, as the bloodline continually has no new qualitiesadded to it the 'bad' qualities it has are multiplied exponentially tothe point the 'good' qualities really don't matter.

In your situation I don't think it would be a problem, but i'd get thetwo vet checked after you get them just to be sure. Good Luck!"

 

[pamnock]

As they are the products of outcrosses and nottightly inbred themselves, there is slightly less chances of themproducing offspring with recessive, undesirablecharacteristics. It should also lend to the offspring havingmore vigor than a tightly inbred sibling cross.

It's impossible to accurately predict what genetic problems they couldpossibly inherit without knowing the genetic history of the parents,except to say that siblings bred together have more of a chance ofcarrying the same undesirable genes and possible recessive defects thanan unrelated pair would.

Sibling breeding is often done by seasoned breeders to identifyrecessive genes carried in the line; traits that could be desirable(such as certain recessive color genes)or undesirable (suchas congenital deformaties).

I have found that breedings from very young stock often end inmiscarriage, so only time will tell if the buck was mature enoughtosire a viable litter.

The risks are not actually "doubled". If each of the siblingscarries an undesirable gene, there is a 25% chance that the offspringwill inherit the defect. There is a 50% chance that theoffspring will be carriers of that undesirable gene and a 25% chance of"normal" non-carriers. If only one of the siblings actuallycarries a particular recessive gene, 50% of the offspring will inheritthe gene, 50% will be normal and none will inherit the defect (whichwould require inheriting that recessive gene from both parents.)



Generations of inbreeding lead to "inbreeding depression" and a herdwith poor vigor, disease resistance and poor reproduciton.Adding new stock can create "hybrid vigor" within the herd and improveproduction.

Pam

 

[rabbitgirl]

Thanks! That should reassure the owners (besides which I find it absolutely fascinating!)

Hey! Does that increase the chances of albinism? I had half hoped for alittle white baby in Tank's litter as it happens in Pal litters everynow and then.

Sigh....wish they were mine! (the owners are a bit overwhelmed at the thought of babies so soon! first-timers!)

Well, I guess we'll find out in a couple weeks! I don't like thethought of October babies in WI--outdoors! But she has lots of hay inthe box.

Thanks again,

Rose

 

[pamnock]

In order for a pair to produce an albino, eachparent must carry the albino gene "c". If neither of the paircarries it, you could linebreed for 100s of generations and it couldnever be produced. When both parents are carriers, 25% of theoffspring produced will be albino. If only one parent carriesit, no albinos can be produced from that breeding, but 50% of theoffspring will inherit the gene. Color genetics (in general)follow a simple mode of inheritance and can be easy to predict if youknow the genotypes of the animals you are breeding.



When you get an albino from a palomino breeding, it means that both theparents carry the "c" albino gene, and that others in the litter wouldhave inherited 1 copy of the gene and carry it recessively.



Pam

 

[rabbitgirl]

Genetics are so cool. Thanks so much, Pam!

Rose