| Mardelin | 04-15-2010 06:54 AM |
Quote:
Originally Posted by mommadog1
(Post 3085919)
I think a lot of them were already breeding the parent breeds and then just started adding the mixes. Know someone who was a very respectable shih tzu breeder and started breeding shih-poos and then shorkies because, (her words) her shih tzu's were not selling as well any more and she is now living off only breeding.
I no longer speak to her, but she isn't lazy.. She spends her whole day caring for those dogs and puppies and manages to keep a clean house.
I am not defending the mixing she does and living off them (I am against breeding for profit..period!), only making a point that she isn't anywhere near lazy.
| Here's some information taking from information in the YT Library
Genetics
If a purebred dog of breed X mated with a purebred dog of breed Y, both meeting health standards for their breed, is there a better chance the offspring would be healthier than a same breed mating because the gene pool is larger?
In terms of health alone the first answer would be that in breeding two healthy dogs it shouldn't matter if they're the same of different breeds, you're apt to get healthy pups. But this doesn't take into account the question of recessives. Suppose you breed two dogs of different breeds that both have the same incidence of a recessive health problem. The pups would have the same odds of having that health problem as purebred pups of either breed. On the other hand, suppose the two dogs were of breeds that have no recessive health problems in common. This would reduce or eliminate the odds of the puppies of having the health problems of either breed. This is the classic explanation for the theory of first generation hybrid vigor. The resulting pups should not be bred though, since they'd have a good chance of having the recessives from BOTH breeds, so the grandpups would be inclined to be worse off than the purebred offspring of their grandparents. An excellent set of articles dealing with "hybrid vigor" can be found in DogWorld, Jan 1997 by George Padgett DVM. Another very important point to keep in mind is that when a purebred carrying a genetic defect is crossed with another breed or mixed breed, the "bad" genes do NOT "go away" even though they may not be expressed in the offspring. If crossed with another dog carrying the same defect, the offspring of that breeding will demonstrate the defect.
When you breed two different breeds together, what kind of variation can you expect?
Pfaffenberger's book has some interesting data on this. He did some experiments with four different breeds. They were dogs of approximately the same size, but very different physical appearance AND behavior. The results he saw in the first and in subsequent mixed generations are pretty interesting.
Let's look at a common crossbreeding: "cockapoos" (which are not purebred dogs, nor registered with any registry). These are crosses between Cocker Spaniels and Minature or Toy Poodles. The dogs actually vary quite a bit, some being more poodle like than others, and some being more cocker like than others. However, they are generally all a small sized, buff colored shaggy dog. If you breed two cockapoos together (not generally done), you get an even wider variation of dogs -- some look like Minature Poodles, others like Cocker Spaniels. The reason for this is the recessive genes hidden in the first cross that came out in the second generation. This is actually a visual example of why "hybrid vigor" doesn't hold. | 