Linebreeding? - Page 1

hamza, simply put, linebreeding is breeding on one certain dog to "set" positive traits that dog may offer. The draw back is that you also set negative traits.

4-5 means that for example Dog XYZ appears in the 4th. generation in the sire side of the pedigree and the 5 gen. of the dam.

Something like 4,4-5 would indicate that DogXYZ is twice on the sire side in the fourth gen. and once on the dam side in the 5th. gen.

In-breeding is generally considered to be much closer breeding, ie siblings, sire or dam to progeny.

Best,
Rik

Hazma, to add a bit to what Rik is saying, the genetic material (genes) are carried on chromosomes. Each dog has 78 chromosomes, which are grouped in 39 pairs. IOW, each chromosome has a duplicate (except the sex chromosomes: the female has 2, ( X X ) and the male has one X and one Y.)

Anyway, when the sperm and egg cells are formed, the cells divide so that each one has only half the usual number of chromosomes. When the egg is fertilized to make a puppy, the number is once again restored to 78, with one chromosome coming from the father and one from the mother.

So, if the father and mother are closely related, the chances are much greater that the genes carried by these chromosomes will be the same. What's wrong with that? You want to fix 'type' in your dogs, don't you? You want them all to look as much as possible like that beautiful foundation bitch and sire you started out with, right? That's the whole purpose of linebreeding.

Well, the problem is, all dogs carry a certain number of defective genes. Often these genes are hidden as recessive genes, that aren't 'expressed' (don't show up in the dog's appearance.)  A good example of a recessive gene would be the gene for black coat in the Shepherd. A Shepherd will only 'express' this gene if it gets two copies of it, one from the father and one from the mother.  A dog with one gene for the black coat and one for a black and tan coat will appear black and tan, as the B&T gene is dominant.

So, to go back to the defective genes....

Some of these can be dominant, in which case, a whole litter can be affected. It's easier to weed these genes out, because you'll always know they are there. They always show up. All you need to do is neuter the affected dogs, to keep them from being passed on.

Getting rid of the harmful recessive genes is much harder, as they will remain hidden. Some breeders claim they can 'weed out' these undesirable recessives by continuing to inbreed/linebreed. I think that's a fallacy.

When any living thing is inbred generation after generation (and inbreeding is only a more severe form of linebreeding) you get inbreeding depression. Offspring become weak, sickly and undersized.  When this starts to happen, the smart breeder will outcross (bring in a dog that's not related to his lines) to restore genetic diversity.

Genetics is a very complex subject, and, of course, we've only scratched the surface here. If you want a deeper understanding of it, see if you can locate a copy of Malcolm Willis's book, Genetics of the Dog. 

http://www.amazon.com/Genetics-Dog-Malcolm-B-Willis/dp/087605551X

Rik's explanation is close, but not quite correct.  A dash between the numbers differentiates which is the sire side and the damside, so that a 4-5 is how she described.  And a 4-4.5 is once on the sire side, and twice on the damside.

Perhaps someone should also explain what causes outbreeding depression, or why close linebreeding on healthy genetics (rather than namesakes) can be such a success.

so if it is 4-5, is the 5 the sire side, and the 4 the dam side, or the other way round.
And rik i'm afraid i cant buy the book, could you send me a website which explains linebreeding, and how it works.

i googled "line breeding dogs" and this site looked to have a pretty good explanation.
www.rhiannon-cavaliers.com/linebreeding.htm

Best,
Rik

that website was very helpful Rik.