Page 1 of 2
Posted: Fri Aug 01, 2008 9:07 am
by Rutherford
Hi, Isabelle if you go to www.dex-info.net/dexter_studs.htm and look up ‘site contents’ you will find a picture and description of a bulldog calf. I hope it is the only one you ever see, I can vouch for the fact that it is calculated to leave you with a very unhappy Dexter mum.
It is mostly aborted at seven months; if it goes to full term it can give birth difficulties. The carrier or ‘short leg’ is a straight cross between a normal animal with the correct genes for the construction of the skeleton and the bulldog calf with very little bone. Although the carrier is described as having shorter legs it is actually the whole skeleton that is reduced. If you mate two carrier animals you have a one in four chance of risking a calf with two dud genes and virtually no skeleton.
Beryl (Woodmagic)
Posted: Tue Aug 05, 2008 4:09 pm
by Louisa Gidney
I've been seaching Google for other bovine pathologies and have come up with examples of bulldog calves in a range of other breeds, including Holstein, Ayrshire, Red Sindhi, Florida Native and Indian Water Buffalo. The hereditary disorders in a lot of other commercial cattle breeds make for very interesting reading. Before we berate ourselves as a breed & start saying commercial breeds won't take us seriously until we exterminate the bulldog, we ought to be more aware of the embedded congenital deformities that are common to all cattle and those that are specific to particular breeds.
I'm actually looking for comparanda to a Complex Vertebral Malformation in one of my homebred reference skeletons. The etiology appears to be distinct from the CVM seen in the Holstein, which is associated, like the buldog, with premature abortion. My boy survived to grow into beef.
Posted: Tue Aug 05, 2008 8:07 pm
by Rutherford
Certainly dwarf syndromes have been common in most breeds. At one time no bull could be exported from Jersey unless it had undergone tests to ensure it wasn’t a carrier. At the beginning of the last century the Hereford and Aberdeen Angus had a horrific time trying to eliminate different types of dwarfism, in their cases the double recessive was born alive. When selling a bull it was common to receive only half the sale price, the balance being paid a year later when he had produced a crop of sound calves.
The difference is that the main breeds have all used intensive methods to eradicate their problems, whereas we continue to ignore it. If an A.I. bull sires a dud calf he is slaughtered, whereas the Dexter Society actually continues to market faulty semen. When exporting semen the owner has to sign to say the animal carries no such defect, yet the occasional Dexter A.I. short leg bull is still finding his way abroad.
There is always the possibility of unwanted fresh mutations occurring, so no breed can say they have no undesirables, it is the lack of reaction on the part of the Dexter Society that sets us apart.
Beryl (Woodmagic)
Posted: Wed Aug 06, 2008 11:51 am
by Louisa Gidney
This is copied verbatim from the Holstein Association USA:
"The gene responsible for CVM has been identified and a DNA test is available. Forms and instructions for accomplishing the test can be requested from the Holstein Association. Hair or semen samples are preferred for this test. The results are available in about three weeks.
CVM is inherited through a single recessive gene. CVM-affected calves can only result when a carrier cow is mated to a carrier bull. When two carrier animals are mated, 75% of the calves will be normal, and 25% will be affected with CVM. Calves that have one defective gene will appear physically normal, and their performance will be unaffected, but they will be CVM carriers.
Many of the bulls that are carriers of CVM will also carry numerous other genes that are desirable for production and type. Absolute avoidance of CV bulls is not necessary but serious thought should be given when using them. Breeders should avoid mating CV bulls to cows whose sire and/or maternal grandsire are CVM carriers."
So you can see that their problem is parallel to ours, but exacerbated by the global use of individual AI sires. The advice given equates to breeding short to non-short Dexters rather than extermination of the carriers.
Posted: Wed Aug 06, 2008 12:48 pm
by Rutherford
Reminds me of a visit I made to an Ayshire herd years ago that was affected by their dwarf syndrome. The owner explained to me that it wasn’t a problem since you merely needed to make sure that one of the parents didn’t carry it. Oblivious to the fact that he was ensuring spreading it throughout his herd. You may find it comforting that another Society is also issuing such dubious advice, I doubt whether it would be considered acceptable this side of the pond. Remember they also encourage various miniature breeds. The Victorians were always attracted to anything odd and bizarre, but on the whole today’s farming fraternity look beyond such incomprehensible fashions. They need their stock to make a living and aren’t so short sighted.
Certainly Aberdeen Angus and Hereford breeders learnt their lesson, I guess the USA Holstein will retract when they find they are being swamped, today I suspect there will be comparatively few. They are at any rate advising care and forethought, whereas we actually fairly recently were insisting that only carrier bulls should be used, and still tend to put the carrier first in the show ring, hardly on a par.
Beryl (Woodmagic)
Posted: Wed Aug 06, 2008 10:32 pm
by Duncan MacIntyre
Posted: Wed Aug 06, 2008 10:42 pm
by Broomcroft
A picture is worth a thousand words, and this case about ten thousand. The one we had on our farm was the same but slightly earlier in it's development and had bare pink skin.
Edited By Broomcroft on 1218080518
Posted: Thu Aug 07, 2008 8:46 am
by Peter thornton
"still tend to put the carrier first in the show ring"
Beryl has gone to the heart of the problem. Carriers are more likely to win shows, therefore fetch good prices therefore we encourage their breeding. We are showing our wares and relying on a deformity to produce the perfect animal.
We should be moving towards a situation where only non carriers are allowed to become show champions. This would begin to solve the problem.
Posted: Thu Aug 07, 2008 12:02 pm
by Sylvia
This has been raised before, several times, and until it is sorted there will be no solution to this problem.
The carrier is the shape which most non-owners recognise as a Dexter and therefore if they ever come to buy Dexters that is what they will expect to get. (at this point they may ask about bulldog calves and will be told they can be avoided - and discover for the first time there are non-short Dexters too) However the strong product image will steer them towards carriers. Due to the fact that these are their first cows they will become favourites.
Later on, with more knowledge and people suggesting that the carrier should be phased out they are faced with a dilema. Their favourites are the very animals which need to be got rid of. The hard headed owner will change over without a backward look, but how many of those people bought Dexters in the first place ? Very few I suspect.
It is DCS which should take this situation by the horns and provide a lead, but they are in the mire at present due to other matters. Until they get their act together there will be no progress. And when they do come to look at the situation they are going to have some difficulty in getting rid of carriers when they have been rewarding them for years in the showring.
This is a monumental mess. And I am very glad that my Dexter breeding days are over, because I can see no way that this mess will be cleared up without anger and heartbreak which will make the goings-on of the past year or so pale into insignificance.
I wish you luck, boy are you going to need it. 
Posted: Thu Aug 07, 2008 12:23 pm
by bjreroberts
I don't know anything about showing and how the animals are judged, but why not award extra points for none carriers and increase the weighting given to this over a period of time.
That way the problem can be erradicated over time without peanalising people overnight?
Posted: Thu Aug 07, 2008 2:02 pm
by Inger
Well short non-carriers are winning in our Dexter Show rings. There is one judge who actively prefers non-carriers as a healthier way to go for Dexters. Less foot problems. Better feet mean a longer life. Especially on the hills we have in NZ. Carriers just can't hack the pace I'm afraid. I'm having to cull them at 5 or 6 years of age. Whereas I've had 13 year old non-carriers whose feet just keep on going.
Our cattle have to be outside all year round, so that's a lot of walking. Bulls especially, have to have good feet. Dexters are supposed to be hardy cattle, aren't they?
If we can get waist high non-carrier Dexters, why would we need to bother with carrier animals? The higher rate of calving problems with carrier cows have sold me on the concept of weeding them out of the herd. I have one carrier bull and once he's been replaced, I'm determined not to get another. No matter how beefy he looks. I'll be keeping his non-carrier daughters in our breeding programe though. He's got great genetics apart from the BD1. Although height isn't one of them. His daughters are mostly taller than average.
Posted: Thu Aug 07, 2008 4:24 pm
by Sylvia
If there were significant numbers of short non-carriers in the UK there would not be such a problem, Inger, but it seems to me (and I stand ready to be corrected) that they are rare and more or less limited to one breeder. Concentrating all future breeding to those animals would be so limiting I can see Dexters back in the rare breeds section before too long.
As for foot and calving problems - if it were generally the case that these are worse in carriers it would provide a sound basis for change. But it was not my experience that either occured in my (once) large herd any more frequently in carriers. The few calving problems we had were fairly evenly distributed between carriers and non-carriers and foot/leg problems did not occur in either type despite our hilly farm, which I accept may be a lot less challenging than yours.
Posted: Thu Aug 07, 2008 6:47 pm
by Broomcroft
I have just come back from the Burwarton Show and only what looked like very short Dexters were on display. We ourselves were as usual showing two breeds of sheep, 12 in total, and 2 horses. And as usual we wouldn't dream of even considering showing a Dexter because we don't do shorts and the few we have are not good ones in any case as it happens.
At the end, the judge made a little speech over the loudspeaker system praising the Dexters and telling the audience how it's beef was becoming more renowned amongst top chefs for it's exquisite flavour, and how it was nearly always grass-fed and natural, and she metioned dual purpose and milk etc. She really did an excellent job for the breed but I do feel that people will have heard what was said, then looked in the ring and wondered whether what they were seeing and what they were hearing were really related!
Anyhow, I went up to the judge afterwards and complimented her on her excellent speech. I also told her that we would never consider showing because it was only little ones you ever saw in the ring. She said, absolutely not, she would welcome any animal that was within the breed standard and judge them solely on the basis of the quality of the animal.
So, we're probably going to show our beef Dexters next year, hopefully not as well as 2 sheep breeds and 2 horses! And if we come last, no probs, we're used to it 
. We actually did very well all round today.
Edited By Broomcroft on 1218131539
Posted: Thu Aug 07, 2008 8:02 pm
by Saffy
Something that has been on my mind for a while and I was reminded of by the mention in the above posts that non carriers are often healthier to a greater age and Clive mentioned his horses at the show.
Horse Shows, even tiny local ones usually cater for the older horse by offering a Veteran Class. I notice that there has been quite a bit of talk on the site about the older cow.
Would it be an idea to encourage those who have cows that preserve well into old age by offering either a Class for the older Dexter animal at a show or a "Special" rosette to be presented to the best animal on the day over a certain age, say 12 years?
Something on these lines hopefully coupled in time with the idea suggested by Beryl a while back of having at least half our judges from non short herds, should make a great difference to improving the lot on the show field of the non short animal.
Stephanie
Posted: Mon Aug 11, 2008 1:52 pm
by Louisa Gidney
Returning to Saffy's original question of how long it would take to breed out the BDC, I thought this might be of interest, especially point 5 below.
National Association of Animal Breeders
Columbia, Missouri
Commonly Asked Questions Regarding CVM
Complex vertebral malformation (CVM) is a recessively inherited genetic defect that was discovered last year by Danish scientists. CVM is suspected to cause embryonic deaths, abortions, and stillborn calves, some with visible deformities. It is important to recognize that CVM is not new. It’s been present in the Holstein breed for many generations, and only the DNA test is new.
How do I know if I have CVM in my herd?
CVM-affected calves will be aborted or born dead. Abortions due to CVM may happen at any time during gestation. Stillborn calves will typically be born 1-2 weeks premature, and the most noticeable defects are the malformed legs with rigid pasterns. A shortened neck may also be visible. But a pathological examination will usually be necessary to detect abnormal curvature of the spine, fused vertebrae, and fused or missing ribs. Producers are encouraged to report suspected calves to Holstein Association or AI representatives. Keep in mind, however, that many CVM calves or fetuses will be lost (much) earlier in the gestation period, and such occurrences will rarely be detected. Further, remember that abortion and stillbirths can occur for reasons other than CVM.
How much could CVM impact my herd?
Although the percentage of cows that are CVM carriers has not yet been well documented, it is likely that most herds will have a few carriers. Several popular sire families have transmitted this defect during the past two or three decades, and the number of carriers in a given herd will depend on past usage levels of these bulls. However, there are effective strategies for limiting the impact of CVM, as discussed below.
Is CVM specific to the Holstein breed, or do all breeds have some carriers?
At this time, CVM has been identified only in the Holstein breed.
Will CVM be a permanent problem for the Holstein breed?
No, its impact will decrease dramatically within the next five years. Modern genetic tools allow us to accurately identify sires and cows that carry CVM through DNA testing, and AI studs will avoid buying young bulls that carry the CVM gene. Therefore, very few CVM carrier bulls will be available 4 – 6 years from now. We’ve already seen a similar pattern for the BLAD gene; nearly 150 US Holstein bulls carried BLAD ten years ago, and very few carrier bulls are available today.
What can I do to control CVM and other undesirable genetic recessives in my herd?
The first step in controlling genetic defects like CVM is to establish pedigree records for the animals in your herd. Once you’ve done this, it’s relatively easy to avoid mating known carrier bulls to cows whose sire or maternal grandsire is also a carrier, because virtually all AI sires will be tested. You can do this by visually inspecting pedigrees, by developing a simple spreadsheet program, or by using a computerized mating program (as discussed below).
Would the use of a formal mating program help control CVM in my herd?
Yes, it certainly would. Existing mating programs do a great job of controlling inbreeding, and inbred animals are much more likely to inherit the CVM gene from both sides of the pedigree. In addition, most AI studs will modify their mating programs to check the CVM status of a cow’s sire, maternal grandsire, and proposed mate(s). But remember, if you don’t have accurate sire and maternal grandsire ID for the cows in your herd, mating programs will be relatively useless.
How do I know which AI sires are carriers of CVM?
Many AI sires have already been tested, and the remainder will soon be tested as well. The Holstein Association labels CVM carriers with a “CV” recessive code, while bulls that have tested negative for CVM are labeled as “TV”. Most publications, such as AI sire catalogs or the Sire Summaries (Red) book will show these codes.
Should I avoid using any known CVM carriers in my herd?
It’s probably unwise to “panic” and exclude all CVM carrier bulls from your breeding program. Many bulls that carry the undesirable CVM gene will also carry numerous other genes with positive effects on milk production, component percentages, udders, feet and legs, somatic cell count, and other key traits. If you discard all of these bulls, you may end up using a somewhat mediocre group of bulls instead, just to avoid CVM. As long as you avoid CVM carriers on cows whose sire and/or maternal grandsire carry CVM, you should be fine. Don’t worry about creating too many new carrier females in your herd, because in a few years most of the available AI sires will be free of CVM anyway.
What if I don’t use AI?
The discovery of CVM is yet another reason to avoid non-AI “jumper” bulls. Virtually all AI sires will be tested for CVM, just as they’ve been screened for BLAD and other genetic defects. But very few, if any, natural service bulls will be tested. It’s likely that one or more of your herd sires in the past was a CVM carrier, and heavy use of a (unknown) carrier bull in your herd could result in many abortions, embryonic deaths, and stillbirths.
Can you provide a “checklist” for managing CVM in my herd?
1) Set up a system for accurate recording of sire and maternal grandsire ID for all cows in your herd, if you haven’t done so already.
2) Make a list or spreadsheet file that shows the CVM status of the sire and maternal grandsire of each cow in your herd.
3) Use a selection index, such as Lifetime Net Merit or TPI, to identify the group of AI sires you’d like to use in your herd during the next 3 months.
4) Check to see which of these bulls are CVM carriers, and avoid using these bulls on any cows whose sire or maternal grandsire is a carrier (you might want to use a mating program for this).
5) Relax, and be glad that modern genetic tools allow us to identify undesirable genes like CVM and eliminate them from our breed in a rapid and efficient manner.
