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Posted: Tue Jul 22, 2008 1:25 am
by PeterO
Hi all from wet NZ - or my part of it 150mm in a couple of days. The cows are looking mournful, the chicken (chooks in local parlance) are sitting on top of the broody pens as their run is 2 ft deep in water, while the ducks think paradise is here,
Question - I have an 8 month old heifer calf born to parents registered as long legged - see photo.
She is short legged - can I register her as short legged (or is she a very short long legged) - or should I take her out and shoot her 
Note the steer calf behind her is only 2 months older (and is long legged).
Posted: Tue Jul 22, 2008 7:41 am
by wagra
Hello PeterO, You can't get a short-leg from two TESTED long-legs. I don't know how your registration system works but ours would register her as 'Free By Inheritance' if she had two tested long-leg parents.
Margaret
Posted: Tue Jul 22, 2008 8:58 am
by Duncan MacIntyre
Why not have her tested? Maybe both for parentage and carrier status. I have tested non carriers who look at least as short as that.
Duncan
Posted: Tue Jul 22, 2008 9:38 am
by Rutherford
I agree with Duncan, photo’s can be deceptive but looking at her general conformation, not simply leg length, I would have said she was a carrier. I would definitely want to do both tests for carrier status and parentage.
Beryl (Woodmagic)
Posted: Tue Jul 22, 2008 11:48 am
by PeterO
Sire is tested NC
Dam is a Grade 3 untested - but visually well Long Legged
Posted: Tue Jul 22, 2008 1:01 pm
by wagra
You seem to imply that you can register as long or short simply on guess work. That would surprise me but I am not up with the workings of NZ registration. I presume that DNA for PV would be essential at least, would that be so, PeterO?
Is it more likely that the parents are not actually tested, and that one could be a carrier?
Margaret
Edited By wagra on 1216728386
Posted: Tue Jul 22, 2008 1:01 pm
by Saffy
Could there have been a mix up of calves when she was born? Did another cow calve at the same time?
Stephanie
Posted: Tue Jul 22, 2008 6:54 pm
by Broomcroft
Maybe the gene has mutated in NZ? Reading about it in humans, that's what has happened and apparently 7 out of 8 human dwarfs are born to non-dwarf parents.
Posted: Tue Jul 22, 2008 9:41 pm
by PeterO
Saffy wrote:Could there have been a mix up of calves when she was born? Did another cow calve at the same time?
Stephanie
No - no mix up at birth - as I said the mother is Grade 3 registered Long Leg (untested) but if she is a carrier it hasn't come out in her leg length
Edited By PeterO on 1216759316
Posted: Wed Jul 23, 2008 3:36 am
by wagra
PeterO, how can she be registered 'long-leg' if she hasn't been tested? Does the NZ association just take a person's word for it? What about bulls, are they just guessed at also? That doesn't seem to make sense to me.
Clive, that would be the last thing any of us we need. There are already 2 tests required for stock with a particular upgraded NZ bull in the breeding.
Margaret.
Edited By wagra on 1216781961
Posted: Wed Jul 23, 2008 6:20 am
by Rutherford
I am no mathematician but percentages can be misleading. The human population extends to many millions; the total Dexter numbers wont come anywhere near one. The human dwarf parent uses modern scientific know-how to avoid the birth of dwarfs, and the less advanced probably resort to infanticide. The Dexter dwarf is actually bred for. These biases nullify the apparent suggestion of any likelihood of high mutation, the risk is something like one in 20,000, it could happen but the risk is minimal.
Beryl (Woodmagic)
Posted: Thu Jul 24, 2008 6:19 am
by PeterO
wagra wrote:PeterO, how can she be registered 'long-leg' if she hasn't been tested? Does the NZ association just take a person's word for it? What about bulls, are they just guessed at also? That doesn't seem to make sense to me.
Clive, that would be the last thing any of us we need. There are already 2 tests required for stock with a particular upgraded NZ bull in the breeding.
Margaret.
Margaret - I assume you are talking about the Grade 3 long legged mother From memory, only bulls were tested for the carrier gene in the UK (I am aware this is changing) so lots of my long leg registered Dexters (in the UK) had never been tested.
I suspect that somewhere in the mother's background is a short leg (carrier) - if not the calf is a midget long leg :D
Posted: Thu Jul 24, 2008 11:53 am
by wagra
Peter, she could have dozens of short-legs in her background, and most likely does, the same as every other Dexter, but if neither sire &/or dam is a short-leg, then neither is the calf. You haven't mentioned the sire.
There are plenty of 'midget' long-legs, although this doesn't look like one of them, but without testing the debate could go on forever and it is all supposition.
I would have to put myself out of misery and find out for sure. $49 Aussie dollars.
Margaret.
Posted: Thu Jul 24, 2008 1:03 pm
by Inger
Yes in NZ the breeder's guess as to leg length was accepted by the Herd Registrar in past years, as that was all there was to go on. These days, some breeders are getting their heifer calves tested as well, if they are from a tested carrier cow or bull.
There are still breeders who refuse to test their herd, in the mistaken belief that what they haven't proven by testing, means they can avoid answering difficult questions about, when selling their animals. Many breeders just don't care whether or not their cows are carriers. They just use non-carrier bulls over them and don't want to pay the costs involved in getting the tests done.
I've even had to go to the lengths of paying for a bull calf to be tested, before I was willing to buy him. I was fairly sure he was a non-carrier, I just wanted written proof, as I've been caught out previously by a BD1 carrier bull that I bought. He didn't look the same as the BD2 cows in my herd, so I had no experience to base my guess on. I thought he was a non-carrier, as his legs looked the same length as our non-carrier bull, so I took a punt. He was an imported bull from Australia and was from a good bloodline, so the temptation overcame caution. BD1 carriers look different from BD2 carriers and bulls can be deceptive in appearance, as I'm sure some of you have found in a few bulls. Only DNA testing gives you a definite answer - most times. (We have had problems with test results being done by one lab, but another lab is performing the tests now and I hope they are more reliable).
The NZ Dexter Society now demands a DNA profile of all bull calves being registered, to keep on the Society's file, for future reference if paternity is questioned and recommends that they get BD1 and BD2 tests done at the same time, depending on the animals in their pedigree.
As new breeders start demanding BD1 and BD2 tests on any cattle they buy, or on their parents, older breeders will be forced to test their animals for financial reasons. That's not to say that buyers only want non-carriers. I've seen requests for short-legged Dexters as well. Its just that the buyers are getting more knowledgable and wanting to know for sure, what they are buying. Testing will become a consumer driven thing.
In Peter's case, I would test the Grade 3 cow and wouldn't be at all surprised if she proved to be a carrier. If she isn't a carrier, then the calf will be of great interest to scientists looking for new mutations of the BD gene. :;): "More genetic toys to play with", as I've heard one scientist say of the rare breed animals that a few people loyally keep, in order that their genetics aren't lost to the next generation.
Its no comfort to Peter, if he has a new version of Chondrodysplasia in his herd, but I'm more inclined to think that her mother was mislabelled at registration. Having the cow tested and the registration papers altered to give the true state of affairs, is probably the best solution in this case. I know I've had to correct registrations of some of the animals I've bought, once I had them tested for BD1 and BD2. The Bull from Australia being one of them. He still throws good beefy daughters and one excellant looking non-carrier son, so I'm still glad to have him, even though its a pain getting his offspring tested if I want to keep them for breeding. Interestingly, they are also taller, on average, than the offspring of our original non-carrier bull.
Posted: Thu Jul 24, 2008 3:06 pm
by Rutherford
Your contribution is fascinating Inger, the British Association is identical in that we accept guesses on females but expect a test when registering bulls. At the time I was collecting samples for the chondrodysplasia answer, it was discovered that many owners were unable to correctly identify the two types; the test is necessary in order to be certain. When I founded my herd there was no test, but even today I would never wish to say I could be certain on all occasions. Are you suggesting that in the case of your second carrier type it is even more difficult? What did make me uneasy is the possibility that some labs. are not reliable, if they make mistakes the test becomes an expensive luxury.