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Post by cddexter on Dec 11, 2014 11:22:18 GMT -5
Honouring Susan's request to keep her thread on the topic of parentage verification, I'm moving over here to a new thread.
"the chondro gene, since it is partially dominant in the gene pair, it's presence is evident in the phenotype of a chondro-carrier"
In my experience, if you have a particularly proportionate dwarf, at around 15 months to 25 months, there is a period when the phenotype is not evident, even with an experienced eye. It is really hard to decide if you are looking at a well muscled non or a really well balanced carrier. If one is looking at one's own herd, perhaps the background knowledge would help, but if you are just a visitor seeing the herd for the first time, looks can be deceiving. And, without the intimate knowledge of the herd background, a less experienced eye will have even more trouble. Test. Cheers, c.
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Post by kansasdexters on Dec 11, 2014 11:42:51 GMT -5
cddexter, In order for anything to show up, in regard to Chondro status, on the ADCA pedigree certificate or the ADCA online pedigree, for the offspring of a Chondro-carrier (sire or dam), the offspring must be tested and reported. Otherwise, their Chondro status field is left blank. I agree that proportionate dwarf Dexters can be more difficult to visually identify, especially to someone that doesn't have any experience with both chondro-carriers and non-carriers in their herd. I also agree that the offspring of Chondro-carriers (and PHA-carriers) should be tested and reported when the animal is registered (which is typically before they are 12 months old). Personally, this is what we do with all of our Dexter breeding stock registrations. Here is an example of how this appears on the animal's ADCA online pedigree page (the dam of this bull is a Chondro-carrier, she was tested and reported): www.dextercattle.org/pedigreedb/ponyweb.cgi?horse=022728&ParentID=016041&Page=1&Sort=6Patti
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Post by cddexter on Dec 11, 2014 15:17:18 GMT -5
patti, I seem not to have made my point.
Your comment was not about certificates, or about if someone breeds both types, or about testing, as your reply to me would indicate.
Despite your statement quoted in the thread name, sometimes it is very difficult to tell phenotypically if an animal is a carrier or not. I've seen thousands of Dexters of both types in herds all over the world, but they weren't my herds and so I didn't have the benefit of knowing the backgrounds. All I'm saying is for your statement to stand, I think it needed a disclaimer, or at least should have allowed for some people, including me, not to be able to definitively say whether a particular animal was a carrier or not, just by looking at it. If you and I are more infomred than most (and from your post you make that claim for yourself) then think how difficult it would be (is) for those not as well trained, to decide. Kirk is pretty sharp, and I'd put him on the side of the knowledgeable.
cheers, c.
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Post by kansasdexters on Dec 11, 2014 15:57:18 GMT -5
C.
Let me spell it out more clearly:
1. This discussion is about registered Dexter cattle, and the original topic focused on parentage verification, prior to registration. 2. In order to register the non-carrier offspring of a Chondro-carrier, as a "Non-carrier", a test for the Chondro allele is already required. If no test result is submitted then the animal's Chondro-status is left blank (it is "unknown")
So, if we have a parentage verified (Sire and Dam Qualified) registered calf, that is shown by pedigree to be the offspring of two Chondro non-carriers, then the chances of that calf turning out to be a chondro-carrier are remote. The chances of that calf turning out to be a chondro-carrier that doesn't show any phenotypic expression of the chondro gene are even more remote.
The current ADCA registry grants Chondro "Non-carrier" status to untested offspring of untested offspring of untested offspring of tested non-carriers, with no parentage verification required at all. This has been going on since 2005-2006, when testing for the Chondrodysplasia gene became readily available to Dexter breeders and owners in the USA. This automatic Chondro "Non-carrier" status for "Obligate" Chondro non-carriers, does not differentiate between animals that have actually been tested as Chondro Non-carriers and animals that have been granted Chondro Non-carrier status with no testing whatsoever, not even parentage qualification for several generations.
The first priority for assuring accurate future registrations is achieving full parentage verification (Sire and Dam Qualified). Testing for Chondro and/or PHA is currently optional and probably will remain so for the foreseeable future. Most people that test for Chondro and PHA, will only report their non-carrier registered breeding stock anyway. Only a few of us report all of the animals that we test for Chondro and PHA.
Patti
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