NZ Postcard and short legs

[Inger]

Yes I have to say that the NZ version (BD2) is easier to pick than the international version (BD1) which you have in the UK. I've had two calves born with BD1 and both of them have looked normal, but smaller than their non-carrier siblings. Its not until they get older that it become more obvious that they are probably carriers. It seems much harder to pick differences in their legs than it is to pick out a calf with the BD2 version. The calves we've had born with BD2 on our farm (not all were owned by us) have been quite obvious from birth. The leg length from the hooves to the knees are shorter than the length from the knees to the body. Also the head is usually more chunky and the body more compact than their non-carrier siblings. Their gait is different as well. They also seem to be at greater risk of arthritis in the joints. A carrier cow we culled last year had the worst arthritis that the butcher had ever seen and she was only 8 years old. Not an old age for a Dexter.

So I'm not surprised that even veteran Dexter breeders may get caught out with some carriers. I'm very glad to have Genetic testing available now.

The difficulty we had with one test provider was their inexperience I think. I've had samples lost, was told by the second lot that they couldn't get a conclusive result from the blood sample - when I'd never had problems from with the first provider. The prices have gone up a lot with the last provider, which is putting people off getting their calves tested. I'm glad I got our breeding herd all tested before the increase. It used to be $90 for the combined test. They have to do the BD1 test first, before they can do the BD2 test. So for our BD1 calves, we only have to get one test done.

The first provider we used for DNA, was able to accept blood samples on blotting paper, as well as pulled tail hairs. The second provider refused to accept the blood samples on blotting paper. We now have a third provider who will take pulled tail hairs or plugs of skin from the ear. They sell a hole punch for the purpose. They send samples to Australia for BD1 and 2 tests four times a year. The DNA profiles are done in NZ.

I was told by one breeder that they had three Chondrodysplasia tests done on one animal. The first they said was inconclusive, the second positive and the third test was negative. He had lost faith in the testing lab.

I think the results are more reliable now, although it still takes an awful long time to get the results back. I guess its the lack of numbers being tested. Then again, at $130 for the combined BD1 and BD2 tests, its a lot to fork out. You would want to be jolly sure that you wanted to keep the animals.
Its probably the reason why a number of people don't want to buy carriers, because of the on-going costs of testing their off-spring.

[Broomcroft]

What are BD1 and BD2 ?



Edited By Broomcroft on 1217151946

[Rutherford]

BD1 is the test we are familiar with; BD2 is a different gene. The Australians allowed grading up bulls, and one which has been used quite extensively in the southern hemisphere carried a similar recessive from another breed, so they now have to test all Dexters with him in their pedigree for both. You don’t need to worry Clive, since it hasn’t been imported into Europe.
Beryl (Woodmagic)

[wagra]

BD2 carriers have Meadowpark Charles in their breeding, an upgraded 4th cross NZ-bred bull, from before the time when dams had to be 4th cross before a son could be registered here.
His breeding is registered as B.Robert/ B.Robert/ BenMacdhui/ BenMacdhui, neither of which bulls is a carrier for either dwarf gene. The base cow was recorded as a red poll/jersey cross.
Bookhams Robert & Shootlands Ben Macdhui were the only way we had of 'going Dexter' back then, in Aust anyway, & I presume NZ. The upgraded 6th & 7th crosses that make up one sixth of our Wagra herd have these two bulls as their Grade 1 & 2 ancestors.
We don't have any Meadowpark Charles in our herd so we have never had to test for that. I haven't ever seen any of his stock, or descendants so far as I know, but I know it sent out shock waves when he sired a bulldog, probably because a lot of us had the original two bulls as the ancestors of our herds, and we were very confused as to how M.Charles could be a carrier.
Margaret.



Edited By wagra on 1217216463

[Saffy]

OK well this is probably another silly question - do you use AI at all?

I don't imagine that you do but it is just a thought as having used it extensively here in the past for up to 125 calving a year I am able to tell you that mistakes are made!!! When the calf is by Belgian Blue or Hereford and you were expecting a pure Freisian/Holsien you tend to notice that a minor mistake may have been made.

Easily done when dealing with lots of small white straws, it only needs someone somewhere in the chain of custody to make a mistake, it doesn't even need to be the person doing the insemination.

Stephanie

[wagra]

Stephanie, is your question addressed to Inger or to me?
We all use AI, or have used it, or have stock from AI bred stock. Thank goodness for DNA & PV.
There were Dexters here a hundred years ago and faded out but this century's Dexters have only been here just over 20 years, most of which have been since the first BSE outbreak, and various subsequent reasons for banning live imports from the UK. A few live Dexters were imported from Canada & USA, but not all that many. Nearly all the cows were heavily flushed and they are the source of the Dexter mitochondrial lines.
Many of the herds here are based on upgraded stock, and it is only a couple of years since the herd book was closed to Grade One registration.
I heard ten or so years ago that a Dexter cow had been AIed with 'Hector'. The mistake was realised in time fortunately, and the cow was aborted, because the Hector that was used wasn't Bogevangen Hector, the Danish Knotting-bred bull, but Hector the Romagnola!!

Margaret.

[wagra]

PS, I would have thought that anyone would check the name on the straw before putting it into the thaw water.

[Saffy]

The question was meant for Inger - yes you would think they would check the name and obviously 999 times out of 1000 or even more that is exactly what they do but absolutely every one of us makes a mistake from time to time - a bit of a shame really. :;):

Stephanie

[Inger]

We have bought straws, but haven't had the chance to use them yet Stephanie.

The beauty of having each bulls DNA profile on file with the Dexter Association, is that if questions are raised as to whether or not a calf was really sired by a particular bull, the calf's DNA can be checked against the possible sires. The calf can then be registered with the correct bull listed as his sire. I've used the service myself, as there have been a couple of occasions when a cow that I had thought was safely pregnant, may have come on heat again. The first time the vet said the gestational age of the foetus didn't match the service dates I had of the selected bull, so I had that cow injected and the second time, the DNA showed that the chosen bull was in fact the sire of the resultant heifer calf. Its reasuring to be able to find these things out for sure. :D



Edited By Inger on 1217420179