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Re: [RC] [RC] SCID: Breeding Decisions - heidiOn Tue, 4 Jan 2005 11:47:53 -0800 (Pacific Standard Time), Cathy <danugna@xxxxxxxxxx> wrote:With ethical breeders, it would be possible to breed the SCIDS gene into oblivion in a rather short time and still keep the good traits of those bloodlines.I wish I could agree, but the mathematics of population genetics are against us. If every breeding Arabian in the world was in the hands of a perfectly ethical breeder, the odds are still that in eliminating the SCID gene, we will be eliminating necessary genetic diversity within a closed gene pool. Thus my suggestion that the goal is never to lose another foal to SCID, rather than eliminating the gene itself. Ambar is right--the goal is not necessarily to eliminate it, but rather to gradually decrease its frequency without losing genetic material along with it. Another pet peeve: "bloodlines" don't carry SCID. Individual horses either do or don't. Amen to that! No matter HOW many proven or suspected carriers are in a horse's pedigree, if he is clear, he is clear! And even if the problem has never come up in a given family, if he is a carrier, he is a carrier! Ironically, the first two stallions of mine that I tested were ones who I knew had close-up carriers in their pedigrees. Both tested clear. It was on further testing of the ones that I did not suspect that I came up with a carrier... And I also have a leased mare here who is tested clear whose parents were BOTH carriers--a mating that would not be done now, due to the risk, but she was born before there was a test, and neither parent had ever produced a SCID foal, so neither was "suspect." Heidi =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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