I "discovered" a chessie pedigree database today that contains COI values.

At what point does the Coefficient of Inbreeding become a relevant factor in evaluating prospective or actual breedings for chessies?

This inquiry may be the $64,000 question. I offer my thanks in advance to anyone who takes the time to enlighten me.

Hello Jefferson,
nice to hear from you.
What database did you read??
Did you read the articles I mentioned??
DD

Thanks for the response. I just noted the reference to the article(s) and will take a look. See the Chessie Database. Perhaps someone on this site could chime in about the database's history and reliability. I enjoyed playing around with the pedigrees. The Freezer x Douce breeding looks really nice.

If there are statistics amongst us,they good figure out in certain constant factors,let's say dogs,bitch and dogs, with fieldtrialtitles A,B,C.What was the COI of them and perhaps,you can predict that at a certain level of let's say p.e. 10 to 13 % of COI is the best.
Do not say that this is nonsense,look at the pedigrees in Chesapeake Roll Call.There must be a relationship,without any doubt.
DD

I believe, DD, that what you propose would only work statistically, if the COI distribution for the population were first determined.

Lisa,
I'm speechless about your knowledge,that example about Caroway/JJdogs
Thanks very much!!!!
I have to study again.
DD

LVL --

What is "it" as in "It can't be done by the numbers"?

Statistically, what DD proposed initially is quite feasible if given COI values for a defined population of dogs. Do I read correctly that you performed a correlation analysis on your private database?

What value would this exercise hold for anyone? No one would know for sure unless the work was done and made available for people to make up their own minds.

Would I rely upon the resulting model in the selection of a puppy? Most likely not. Would the resulting model be of some influence? Perhaps.

My original question is when does COI become a relevant factor.

If your answer is that COI never becomes a relevant factor, I will accept that as your answer and believe your answer is incorrect.

If your answer is we simply do not have a enough data to know what COI values become relevant or that COI values themselves are meaningless, I could probably go along with either of those answers but would then ask why we calculate COI in the first place.

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Don't go by some arbitrary number; go by the quality of the individual dogs being bred together, as well as any production history of those individuals.

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- Please.

Jefferson writes:"If your answer is we simply do not have a enough data to know what COI values become relevant or that COI values themselves are meaningless, I could probably go along with either of those answers but would then ask why we calculate COI in the first place."

These are most likely calculated because they can. In a large population they might be meaningful. But consider that in the Chessie world there are only 1000 litters registered each year with a resultant 3700 pups registered. Also consider that the Chessie gene pool is so small and compact that every one of these 3700 pups can be traced back to a single common ancestor. And then try to relate that as to the intent of the COI.

Another consideration is that the COI can also reflect the reverse of what is implied here in this thread. It can also reflect the magnification of undesired traits that are passed along by these tight breedings. The whole trick in breeding is to try to offset or minimize the undesired traits while accentuating those desired traits you value. And in doing this there are always offsets, trade offs, and a large degree of luck involved.

T.Mac

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It can also reflect the magnification of undesired traits that are passed along by these tight breedings.

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Exactly. Thanks for your response.

As for what constitutes a "large" population for statistical purposes, I believe the population is large enough for meaningful analysis. The ability to trace to a common ancestor makes the COI parameter more, rather than less, significant a consideration. I disagree that the number is "arbitrary" as expressed elsewhere in this thread.

As it will state what I'm thinking about breeding,is that there a rational factors wich one can measure,and social wich one can see and emotinal wich one can feel.
It will always be a combination one can figure out more or less.
All people involved in this discussion are thinking about one or more things and that is quiet something for the goals we are striving for namely healthy,positive,good puppies,sound and a big contribution for the breed.
Big BUT,WE can think and discuss,but what about an ACC,who have time,money and people,in my opinion,to figure this out.
It's also for the ACC as representitive and responsible org. to work on this.Or am I wrong,plse tell me,and can somebody of you folks start a topic with teh ACC.
And one other thing ;hat means a small genetic pole?To what is this compered?Is 1000 dogs small???
DD

Lisa -- Thanks for the clarification and description of your work on COI & Fertility. Do you know the history of the database mentioned in the post that started this thread? Are you aware of any other initiatives to determine whether a relationship exists between COI and desireable/undesireable characteristics? For example, has anyone looked at aggression as a possible function of COI? OR, is there concensus that agression is the result of a lack of socialization? Thanks again, Jeff

Lisa,
I agree with you about the lack of relationship of inbreeding and fertility. We learned in vet school that inbreeding might lower fertility, but my personal experience does not support this.

Mario

LVL --

Thanks for the explanation of your work. I too have crunched a bunch of numbers in my career, but several years have lapsed since my last genetics course.

Are you also saying COI is calculated for chessies simply because it can be calculated? Tom M implied that was the case in his post above.

Are you saying COI values are meaningless for identifying certain predispositions in chessies? I named aggression just as an example. Either PRA or hypothyroidism would have better served as examples.

It sounds like your exercise with Claire McCall ruled out the possibility of "arbitrary" COI values.

My question is simply: At what point does the Coefficient of Inbreeding become a relevant factor in evaluating prospective or actual breedings for chessies?

"Relevance" could be on the basis of "health", field performance, . . . Do we even know if COI becomes relevant at any value other than a value of 1 (one)?

Jeff

LVL --

Thank you very much for the explanation.

I clearly see your point now and also see how COI could be and is misconstrued and assigned relevance when and where any relevance is buried in the complexity of multiple genes.

Thank you very much for taking the time to respond. You certainly seem to have a keen interest in this topic and have done quite a bit of related investigation.

I wish you well with your tests/trials this year.

Jeff

I finally got re-connected to Team Chesapeake (after changing email addresses). COIs have been used extensively in predicting yields of agricultural crops and breeds. In most of these species, yield (gallons of milk/day, bushels/acre, etc.) and fertility are the result of interactions between many genes, as well as the environment. In general, yields decline as inbreeding increases. That's why Mario and I though about looking at fertility in Chessies. Clearly, we were wrong, probably because of the reductions in population size that the breed has gone through in the past. For single gene characteristics, such as PRA, you can (as Lisa suggested) evaluate the probability that an animal has PRA based on their pedigree, but a COI by itself isn't informative.

Lisa, there's one thing you mentioned about your fertility analysis that gave me pause. When hypothyroidism results from autoimmune thyroiditis, isn't it possible that it could be correlated with the animal's COI? My knowledge of autoimmune diseases is miniscule compared to yours, so I'm probably wrong. Still, I'd like to know _why_ I'm wrong!

Claire

If you're wrong,then rhre is a contradiction between the constant and variable factors wich are not specicfic identified!
And what about statisticall analysis with WilcoxonRank-tests?
DD