COI Whats The Ranges To Watch For?

TNBeagler4LIFE · Post by **TNBeagler4LIFE** » Sat Jul 23, 2005 6:02 pm

COI

I like to line breed... However, i was wondering if someone could help me out as far as what to watch out for... What are standard limits one should push the bar?

Thanks,
TNBEAGLER

xdawg · Post by **xdawg** » Sun Jul 24, 2005 4:59 pm

With the program i keep my dogs in it calculates COI too... I too have been wondering what to watch out for.... Whats TOO HIGH?

Thanks,
Jack

Lefgren-Lane · Post by **Lefgren-Lane** » Sun Jul 24, 2005 8:32 pm

When COI's are quoted it is appropriate to quote the number of generations used to calculate it. If the number of generations are not stated then it is assumed that 6 generations were used. (Some suggest that you have to have at least 10 generations to know what is going on. I disagree as I've never found a COI calculated using 6 generations that differed very much from the 10 generation. Using less generations (3, or 4 especially) than 6 can get you results that can differ quite markedly from 6 generations. If you were to calculate the 6gen COI for every animal in a breed and then average them you would normally find that in breeds with large numbers etc like beagles that the breed average for COI in will be about 5 percent. In looking at a lot of peds over the years the highest 6 gen COI I have ever seen is about 42 percent. The highest COI I've ever bred is about 36 percent. Research at Iowa State College done on a closed beagle colony back in the 1930's and 40's and quoted in the book Genetics for Dog Breeders by Robinson, 2nd edition 1989 showed that COI's up to about 50 percent had very little effect on the outcome of breedings. COI's above 50 percent there was indications of loss of fertility, smaller number of off spring, problems with health and size etc. Now a 50 percent COI is something like 4 generations of brother to sister or father-daughter, mother-son matings etc. Most of us will never get close to anything like that. When I am looking at future breedings or plans, I try to keep COI's below 35 percent or so but would go above 40 percent if there was a very compelling reason to do so. For those that are interested you might try taking a look at the pedigree for Sally Dix on http://www.worldpedigrees.com. Her 6 gen COI is over 40 percent and about the highest I've ever ran through my computer. If somone can show me a ped with a higher COI, I would really like to see it. (Do not confuse COI (Coefficents of Inbreeding) with Percent of Blood calculations. They are very different and the COI is probaly the more useful of the two.)

Lefgren-Lane · Post by **Lefgren-Lane** » Sun Jul 24, 2005 9:34 pm

When people quote COI's it should be noted that most use Wright's Coeficient of Inbreeding numbers, although there have been other methods of calculating COI's proposed from time to time. (Wright was a professor at the Vet school at the U of Missouri in the 1920's). For a good quick overview of COI etc. read the Help files available with the free Pedigree program, Visible COI programs and the manual from this web site. There are also reference books listed in these files.

http://www.geocities.com/willowind_dals/pedigree.html

Another useful work is The Theory of Inbreeding written by Sir Ronald Fisher in about 1906 or so. It was reprinted in about 1985. It is pretty heavy mathematically (he was a mathmetician). A lot of examples of breeding patterns, the associated math etc. for autosomal, hybrid breeding. plants and animal, sexlinked inheritance etc. heavy in matrix math, especially for a book written so early in the 1900's.