Preston Owens
UKC Forum Member
Registered: May 2009
Location: Grant County AR
Posts: 1279 |
good article
submitted by Dow Hale:
........................Inbreeding
..........Dr. R.A. Guill geneticist
I think there is somewhat of a misconception about inbreeding and/ or linebreeding. Inbreeding is the breeding of two individuals more closely related than the average inbreeding of the population from which these two individuals were taken, Linebreeding is a mild form of inbreeding usually where one individual keeps showing up on one side of the pedigree.
I have read advertisements where people say they have bred granddaughter to a grandson of old so-and-so and the pups will have 50% of his blood. These pups infact would only be slightly over 3% inbred. Inbreeding is expressed as Inbreeding coefficents which are calculated by the formula Fx=(1/2)n-1(1Fa). These coefficients are only statistical values acquired by the number of generations the animal in question is removed from its common ancestor. These coeffients are theoretical values assuming every gene on every chromosome has equally 1/2 chance being passed on to the next generation.
When practicing an inbreeding program one should look very closely at the individuals used.For example,when breeding half brother to half sister,these two individuals should be very much like the common ancestor from which they got their outstanding characteristics.If one was like its dam and the other one is like its sire there is no need to inbreed these two individuals because you are not concentrating on the genes of one individual. Father to daughter,and son to dam are also methods of inbreeding.Here again,only breed a sire to his daughter if that daughter is very much like her sire and the same for son to dam.There would be no need to breed a son to his dam if the son was like his sire,you would not be accumulating the desirable genes of the dam which is the purpose of inbreeding. I would not advise Full Brother -Sister matings because you do not know which common ancestor you are accumulating the traits from the grandam or grandsire.
The following list shows some of the inbreeding coefficients of certain crosses: (assuming none of the ancestors are inbred)
1.Sire X Daughter .25
2.Son X Dam .25
3. Full Brother X full Sister .25 (.125 from each grandparent)
4.half brother X Half Sister .125
5.Sire x grandam .125
6. sire X granddaughter .125
7.nephew X Aunt .0625
8. Niece X Uncle .0625
9.Double first cousins .0625 (.0156 from each great grand parent)
10. first cousins .03125 (.0156 from two great grandparents)
I also think people are confusing open and silent trailing ability, which doesnt have anything to do with inbreeding other than the fact that you can increase or decrease this trait by inbreeding.Most dogs of the hound variety, can smell about the same,the difference is not in the nose of the dog but the excitability threshold. How much scent does it take to excite that individual before it will bark. This is the trait we are breeding for. The same type inheritance is involved in treeing. It is controlled by multiple genetic factors. A dog isnt either open or silent nor will he bark treed or wont bark treed! It just isnt that simple,there are multigenetic factors involved in these traits and we use the treeing because by in large those dogs that are real hard hunters,good strike dogs and trail dogs are not as good on the tree.Where as the the real good tree dogs are not quite as good on hustle,strike,and trail.We are beginning to break up these linkage groups because we are breeding lines of dogs that are better in striking,trailing,and treeing.
The reason it is difficult to get everything in one individual is because of the number of traits we are selecting for.Suppose we are selecting for tree barking,tree locating, tree holding (all of which are different) Hustle,quick strike,ability to move a track once struck,voice,right amount of voice depending on type of track,handling ability,conformation,color. This would put eleven whe N is in the formula,that is if we give each trait the same weight on selection. Therefore X would equal .3, or we would expect this much progress in our breeding program if we had all these traits in our breeding stock. We dont make this much progress each generation,but we are making such faster advancements than in the past. One important Fact we cannot overlook,is the difference in the way people are handling and training these dogs. genetic makeup is only 50% and environment plays the other 50% of what each hound makes. So to have an outstanding hound,you must have one that has the genetic makeup to be outstanding, then the rest is left up to the trainer.
I thought this article was very well written and thought Id share it with all of yall. Ive read it countless time over the years to remind me how important the SELECTION process is. I hope yall enjoy it
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02-25-2013 11:29 PM
