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Post by Deleted on Dec 3, 2014 0:44:16 GMT
Are there any types of charts or methods of judging
the potential height or weight of a 1 to 3 year old before
getting to 3 to 5 years and saying oh crap.
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Post by genebo on Dec 3, 2014 2:30:57 GMT
None I know of that work.
That has been a matter of discussion in the past. It's the reason that the age of 3 years was specified as the official measuring age.
Brenn measured 39" at 3 years. When he was collected, at 43 months old, he was recorded at 41.5". He is 10 years old now, and the 41.5" height is accurate.
I have never had an accurate weight for any of my Dexters after they were newborns. Weight tapes and eyeball guesses had to do. The only predictors I had for weight was the parents. Brenn's bull calves were fairly uniform in size and weight. His heifer calves tended to grow to a height slightly less than their own.
The best method I know of for predicting height and weight of the calves is to carefully select the parents.
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Post by Deleted on Dec 3, 2014 2:42:20 GMT
Just realize that they are not done growing. At 1 they still have a long way to go but by 3 they only have some more growing to do.
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Post by genebo on Dec 3, 2014 2:56:33 GMT
One of my first Dexter cows was Beth. She came to me as an 8 year old standing 42" tall. She grew another inch in the next couple of years, then held that height the rest of her life. I'm betting that her 3 year old height was 40", based upon the height of her offspring.
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Post by Deleted on Dec 3, 2014 11:22:32 GMT
Ok so we were at a show 3 years ago and decided against
Dexters because they were all about the size of 3/4 grown
beef cow. We had been looking for a smaller milk/beef cow.
Then we went to a Mini Herford show and they seemed even
larger and decided on a Dexter. We had never seen ether.
When I arrived at the mans barn to see Lucy I fell in
love with them. I saw her dam and sire another cow and
heifer. I was told the hieghts and a estimated weight.
I thought I was informed enough. I do remember the bull
he was 39" and to my eye just great looking. He kept come
to us and I was concerned but in hind sight the was good.
Last year we helped with our O V D A show and I saw a
breeder with a herd and don't believe there was any over
over 36" tall. He told me he loved his short's and they
were cute. Sorry to ramble but am trying to wrap my
brain around this and it is hurting.
We will need to be carful in what we do. I will not be
able to have a large herd our land here is around 8,500
to 19,000 a acre. Two 160 acre farms sold last month one
brought 9,400 the other 18,900.
Is their a old record of the weight and height?
What is considered a minimum weight and height?
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Post by cascade on Dec 3, 2014 16:42:52 GMT
Add 5 to 9 inches to chondro carriers to get their true genetic height. The chondro gene is a genetic disease that interferes with normal cartilage and bone growth and hides the much larger true genetic height of the animal.
Chondro carriers do NOT breed true, so half of their offspring can be MUCH taller than they are.
There is only one way to have an entire herd of truly short cattle and that's the way the Woodmagic herd did it... Get rid of the chondro gene (it just hides the true genetic size of your cattle), and breed out of the truly shortest and best cattle that you can find. Keep the shortest and best for future breeding.
When selecting for naturally smaller animals be careful to NOT accidentally select for weaker or diseased animals or deformed animals.
PS. It's misleading to talk about the heights of animals without disclosing their Chondo status EVERY time.
PPS. Using the term "shorts" instead of "chondro carriers" is VERY confusing because the true shorts are short but without chondrodysplasia
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Post by Donlin Stud on Dec 4, 2014 19:28:57 GMT
Hi This has, and is still an issue we are trying to work through while having the breed standard in one hand and eyes running over our mixed herd of shorties and longies. For now we are tending towards the breed standard height to be that of the longies so have taken 20% off to give us a guide for our shorties, especially since the Aussie Dexters are the result of a grade up program and many breeders find height is a major issue that is/needs addressing. We are working on the assumption that we can be too tall but not too short should we 'get it wrong' in our assessment of what the heights in the standard are meant to truly represent. We are recording weights as they walk through the crush but we don't believe we can start to consider weights at this time while trying to get back to the 'traditional' looking Dexter. We have noticed our calf weights at one week of age are 'dropping' with this years calves all being around the 14 kilos for both the shorties and longies instead of the stated 17 kilo minimum expected weight. Looking across the paddock just now, our longies appear to have a height to body ratio of 50% while the shorties are about 60-40. One heifer calf from last year appeared to be heading to the 'too-tall' as she was about the 40 to 60 ratio at 6 mths. But she appears to have been one that went to her height very early as she is now one of our smaller longies who is also very well balanced in her ratio at 14 mths of age. Only time will tell if she ends up 'outside' our determined height choice  |
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Post by cascade on Dec 4, 2014 19:46:51 GMT
Hi This has, and is still an issue we are trying to work through while having the breed standard in one hand and eyes running over our mixed herd of shorties and longies. For now we are tending towards the breed standard height to be that of the longies so have taken 20% off to give us a guide for our shorties, especially since the Aussie Dexters are the result of a grade up program and many breeders find height is a major issue that is/needs addressing. We are working on the assumption that we can be too tall but not too short should we 'get it wrong' in our assessment of what the heights in the standard are meant to truly represent. We are recording weights as they walk through the crush but we don't believe we can start to consider weights at this time while trying to get back to the 'traditional' looking Dexter. We have noticed our calf weights at one week of age are 'dropping' with this years calves all being around the 14 kilos for both the shorties and longies instead of the stated 17 kilo minimum expected weight. Looking across the paddock just now, our longies appear to have a height to body ratio of 50% while the shorties are about 60-40. Only time will tell if she ends up 'outside' our determined height choice One heifer calf from last year appeared to be heading to the 'too-tall' as she was about the 40 to 60 ratio at 6 mths. But she appears to have been one that went to her height very early as she is now one of our smaller longies who is also very well balanced in her ratio at 14 mths of age. Interesting information (and probably good information) but highly CONFUSING information. The use of "Shorties" vs. "Longies" is confusing and misleading. Are you talking about the Chondrodysplasia Lethal Gene ? and Chondro-dwarfs? There are LOTS of "shorties" that don't have the lethal dwarfing defect gene. Perhaps you can clarify your post by changing your wording to use "Chondro-Dwarfs" vs. "Non-Chondro" |
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Post by Donlin Stud on Dec 4, 2014 20:57:08 GMT
No Cascade I, we won't use the term Chondrodysplasia Lethal gene since half our herd are alive and very healthy.
We have longies, those who have a developed canon bone same as the majority of bovine breeds, and then we have those whose canon bone has not developed the same as the majority of bovine breeds.
Body type is the same ( well it should be) when you place a piece of paper hiding the legs of photographed Dexters.
For us, this is how we are going about cementing type in our herd.
And yes we do have a WM Hedgehog III grandson who is very much WM - looks like he is a shortie (60 to 40% height to body ratio) but he is not - tested a longie and while he is a contributing factor in controlling height in our calves, the jury is still out whether we 'encourage' that ratio in our stud's longies conformation.
At this point in time -the answer is no with us rehoming a couple of his offspring who have tended towards the same. This wasn't the only determining factor In rehoming them but one of a few
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Post by cascade on Dec 5, 2014 2:22:00 GMT
Very confusing
So the secret code works like this?....
There are "longies" that have very short legs (like many Woodmagic animals do)
And there are "shorties" that have rather long legs (that's why DNA testing is needed)
So it seems that:
"Shorties" = nothing to do with the actual length of legs, it's just a white-washed secret code word for Chondro-Carrier.
"Longies" = nothing to do with the actual length of legs, it's just a secret code word for the NON-Chondros
Since "longy" and "shorty" have nothing to do with the actual length of legs, then maybe it has to do with length of life of the animal?
"Longy" = NON Chondro Carrier = Live a LONG life
"Shorty" = Chondro Dwarf = Live a SHORT life (Early Arthritis takes out most of them halfway through their life)
Is "Super-Shorty" the code word for the dead deformed bulldog looking calves? They have super-short lives.
Sorry for being so logical...
But I do like your approach of making a 20% adjustment on size which means that a
41 inch chondro bull likely really has 49" genetics
and a
39 inch chondro bull likly really has 47" genetics
You seem to have the MOST logical approach to it of any of the chondro-breeders I've seen, but I do wish you'd come up with just a little less confusing way to identify the Chondro-carriers vs. the Non Carriers. I won't complain (very much) if you leave out the lethal part. Chondro vs. Non-Chondro seems to be what most people are using and is the most clear and accurate.
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Post by lakeportfarms on Dec 5, 2014 3:16:01 GMT
Keep posting, and keep digging Kirk.
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Post by Donlin Stud on Dec 5, 2014 5:01:16 GMT
Cascade, our height sets are:
Bulls
Non-BD1: 40-44 inches
BD1: 31-35 inches
Cows
Non-BD1: 38-42 inches
BD1: 29-33 inches
Two other Aussie studs have 15 and 17 year old shorties, without arthritis.
We are assessing height to body ratio and at this time would remove any shorties who had 'long legs' when assessing that ratio.
Hence my comment above: jury is still out on the longie bull who has a height to body ratio of what we deem to be that of a shortie.
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Post by cascade on Dec 5, 2014 5:16:18 GMT
Cascade, our height sets are: Bulls Non-BD1: 40-44 inches BD1: 31-35 inches Cows Non-BD1: 38-42 inches BD1: 29-33 inches Two other Aussie studs have 15 and 17 year old shorties, without arthritis. We are assessing height to body ratio and at this time would remove any shorties who had 'long legs' when assessing that ratio. Hence my comment above: jury is still out on the longie bull who has a height to body ratio of what we deem to be that of a shortie. Love your approach! (for newbies reading this, BDI = abbreviation code for one of two Chondrodysplasia Genes in World-Wide Dexters) I assume this is at 3 years of age? So a 39.5 inch or 41.5 inch Chondro bull would be considered VERY large and would compare to a 48" or 49" Non-Chondro |
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Post by wvdexters on Dec 5, 2014 22:37:40 GMT
Hee, Hee, Hee Add 5 to 9 inches now?  ? Is that what it is this week Kirk?? I had no idea. We'll have to remember this bit of information. Oh, if only it were fact. (As it is being represented here. Or should I say misrepresented??) Anyway .... I thought it was 8 in another post you made. And I remember reading 3 or 4 to 7 being the "magic numbers" before this. I gotta say though, it's definitely going up!!!! LOL Anyway I just gotta ask are you making this stuff up as you go along? Or are these numbers you are giving out in a very factual way, coming from that study you all love to reference? You know that small one, done very unscientifically yrs. ago. You know the one that included Dexters and cross breeds. It is so interesting that you (portraying yourself as a man concerned with science and facts) would even consider making such a statement. First off, we breed Dexters here. Not larger crossbreeds. I tell you what. Perhaps a great move would be to get some Dexter x Holstein chondro carriers. Measure and compare them and then you can claim an even larger number. You may even be able to get into the double digits with that one. LOL Anyway, joking aside, because this is a serious matter; Very serious in fact. What you have here is simply a theory. An unproven theory at best. The next step should be to do research, test. You have no carriers/ no personal information or experience to bring to this discussion. Research: You have been informed countless times by many mixed herd breeders (those who both own and breed chondro carriers and chondro non-carriers and actually have first hand knowledge and experience that this theory does not stand up in the field. The numbers you insist on quoting are wrong. They do not hold true. But yet you continue to give out this misinformation repeatedly. WHY? Is it because you believe that the carrier breeders are lying and being less than genuine? Or is it that these numbers just fit into your anti-chondro mission so well, that you can't help yourself but to keep repeating them as fact. Even though you know better?? |
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Post by cascade on Dec 5, 2014 23:31:56 GMT
Hee, Hee, Hee Add 5 to 9 inches now? ? Is that what it is this week Kirk?? I had no idea. We'll have to remember this bit of information. Oh, if only it were fact. (As it is being represented here. Or should I say misrepresented??) Anyway .... I thought it was 8 in another post you made. And I remember reading 3 or 4 to 7 being the "magic numbers" before this. I gotta say though, it's definitely going up!!!! LOL Anyway I just gotta ask are you making this stuff up as you go along? Or are these numbers you are giving out in a very factual way, coming from that study you all love to reference? You know that small one, done very unscientifically yrs. ago. You know the one that included Dexters and cross breeds. It is so interesting that you (portraying yourself as a man concerned with science and facts) would even consider making such a statement. First off, we breed Dexters here. Not larger crossbreeds. I tell you what. Perhaps a great move would be to get some Dexter x Holstein chondro carriers. Measure and compare them and then you can claim an even larger number. You may even be able to get into the double digits with that one. LOL Anyway, joking aside, because this is a serious matter; Very serious in fact. What you have here is simply a theory. An unproven theory at best. The next step should be to do research, test. You have no carriers/ no personal information or experience to bring to this discussion. Research: You have been informed countless times by many mixed herd breeders (those who both own and breed chondro carriers and chondro non-carriers and actually have first hand knowledge and experience that this theory does not stand up in the field. The numbers you insist on quoting are wrong. They do not hold true. But yet you continue to give out this misinformation repeatedly. WHY? Is it because you believe that the carrier breeders are lying and being less than genuine? Or is it that these numbers just fit into your anti-chondro mission so well, that you can't help yourself but to keep repeating them as fact. Even though you know better?? Actually, if you look carefully above, you'll see that it's the poster "DonlinDexters" who is a chondro-breeder, who has developed this comparison Bulls Non-BD1: 40-44 inches BD1: 31-35 inches Cows Non-BD1: 38-42 inches BD1: 29-33 inches note: (BD1 = Chondro) DonlinDexters, as a chondro-breeder, has done some good research and measuring and analysis and uses a 20% rule (it's not perfect but it's one of the best I've seen)... The rule says that the chondro gene interferes with normal growth and essentially dwarfs the animal by 20% as compared to its true genetic potential. So Donlin considers a 44 inch non-chondro bull to be equivalent to a 35 inch chondro bull. Using Donlin's method, any non-chondro bull over 44 inches at 3 years, is too tall, and any chondro-bull over 35 inches at 3 years is EQUALLY too tall. By taking this approach, DonlinDexters can work on True-Short Dexters AND Extra Short Chondro-Dwarf dexters at the same time... and can do it HONESTLY by telling any buyers that a 40" chondro bull is actually very large (5 inches OVER her limit). One of my problems with the Chondro gene, is that is masks the true height genetics of animals and messes up the ability to breed for truly shorter dexters. DonlinDexters' brilliant plan mostly solves that problem. If I've misspoke, I'll let DonlinDexters correct me.... I'm slowly becoming a fan of DonlinDexters. . |
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Post by wvdexters on Dec 6, 2014 1:18:57 GMT
NO, no, no. You're not walking out of this one. This is what you do, and have been doing it for yrs.
Please go back and re-read the posts again. Donlin had not even posted when you gave us your new and updated 5 to 9 "information". So let's just stay on topic and leave her out of this. It is YOUR posts we are discussing
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Post by cascade on Dec 6, 2014 2:45:08 GMT
NO, no, no. You're not walking out of this one. This is what you do, and have been doing it for yrs. Please go back and re-read the posts again. Donlin had not even posted when you gave us your new and updated 5 to 9 "information". So let's just stay on topic and leave her out of this. It is YOUR posts we are discussing "What I do" is try to discuss things honestly and scientifically The two Chondrodsyplasia genes found in World-Wide Dexters, are sometimes labeled as BD1 and BD2 (stands for Bulldog1, Bulldog2). They are broken, mutated, Aggrecan (ACAN) genes. The good version of the ACAN gene instructs the chondrocytes to build normal cartilege. Chondrocytes are the cells that lay down the cartilage in a matrix. Osteocytes (bone building cells) act on the cartilage matrix to form bone. If the chondrocytes are disrupted with a defective ACAN Gene (BD1, BD2), then the cartilage and bones (especially the longer bones) can't grow normally and the animals' height is shortened. The Chondrodysplasia genes are NOT recessive. They are co-dominant with the normal gene. That means they can't hide. One bad gene = dwarf cow, two bad genes (and no good gene) = major birth defect and death. Looking online at various sites and studies, I'm finding the shortening effect of the chondro gene reported variously at 5"-8", 6"-9", 7" - 12" (on larger breeds)... The reports show that the larger the animal, the greater the number of pure inches of reduction. Use the chonro gene on a big line of Holsteins and you might dwarf a bull by 12" But I have been won over by Donlin's excellent logic. That's what smart people do... they listen to logic and update their information when appropriate. A 20% reduction (or thereabouts) would account for the fact that the gene tends to dwarf larger animals more in pure inches and dwarf smaller animals less in pure inches, but roughly the same percentage on average. If you have reason to doubt Donlin's 20% figure, you should tell us why... and let her respond. She's pretty smart. |
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Post by lakeportfarms on Dec 6, 2014 12:42:13 GMT
Again you're cherry picking numbers to suit your narrative. We all appreciate what Donlin is doing, and her enthusiasm for the shorties, but these are her goals. They are relatively new to the breeding of chondro Dexters, and Australia is a very different situation than the United States. She has a much more difficult task ahead of her to bring her sizes to something comparable to what we have here, because of the limited genetics available to them, and to be honest, a lot of upgraded Dexters in Australia to start out with. In fact she refers to her height measurement for the shorties as a "GUIDE". Get it Kirk? There is a difference between "guide" and your actual results following years of breeding.
I do expect she'll easily attain her goal of MUCH smaller Dexters than what you can find there in Australia. Have you seen some of the polled so called "Dexters" they're breeding there? It puts some Angus to shame! Since if I post some photos I'm going to get hammered by the lurkers here that are fans of them, message me and I'll point you to some websites where you can see some examples of these enormous Australian "Dexters".
I have no doubt Donlin has initially selected for the smallest Dexters that she can find there. Of course you've jumped on her 20% number because you think you can take it as fact and repeat it over and over again thinking others will do the same. That is not being honest or scientific, it is pure and simple your agenda that you are stating here, you fool nobody who's been around a while.
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Post by Publius on Dec 6, 2014 14:42:21 GMT
Awesome. I get it now Guide as in GUIDELINES for the hip height.
That makes sense to me now.
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Post by cascade on Dec 6, 2014 16:45:42 GMT
Science tells us the Chondro-Defect gene interrupts normal bone growth Science tells us it typically shortens larger cattle the most and smaller cattle less. Science tells us that the AVERAGE dexter bull is shortened by 8 inches, some 9 inches (or more) From the ADCA Website, Cavanagh Study: "The result is most visible in long bone growth because there are growth plates at both ends of those bones, which doubles the effect. Dr. Julie Cavanagh, University of Sydney (AU), discovered the genetic location of the mutated gene and presented her findings at the 2002 International Dexter Congress, and a test followed soon after. Dr. Cavanagh found that when she averaged the heights of the cows and bulls with and without chondrodysplasia that formed her database, there was an overall average difference between carriers and non-carriers of five and one-half inches in cows and eight inches in bulls." www.dextercattle.org/adca/adca_article_chondrodysplasia.htmlDonlinDexters is using a 20% reduction. On a 40 inch non-chondro bull, a 20% reduction would be 8 inches, just as Dr. Cavanaugh's study states. So DonlinDexters took the Dexter standards of maximum 44" bulls and applied a 20% reduction and she came up with this: Bulls Non-BD1: 40-44 inches BD1 (chondro): 31-35 inches Cows Non-BD1: 38-42 inches BD1 (chondro): 29-33 inches I think DonlinDexters did a pretty good job of evaluating the SCIENCE and developing a good scientific approach. Perhaps it's not perfect, but I haven't seen anyone here offer any suggestions for improvements based on SCIENCE. |
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Post by lakeportfarms on Dec 6, 2014 18:24:20 GMT
Science tells us the Chondro-Defect gene interrupts normal bone growth Science tells us it typically shortens larger cattle the most and smaller cattle less. Science tells us that the AVERAGE dexter bull is shortened by 8 inches, some 9 inches (or more) From the ADCA Website, Cavanagh Study: "The result is most visible in long bone growth because there are growth plates at both ends of those bones, which doubles the effect. Dr. Julie Cavanagh, University of Sydney (AU), discovered the genetic location of the mutated gene and presented her findings at the 2002 International Dexter Congress, and a test followed soon after. Dr. Cavanagh found that when she averaged the heights of the cows and bulls with and without chondrodysplasia that formed her database, there was an overall average difference between carriers and non-carriers of five and one-half inches in cows and eight inches in bulls." www.dextercattle.org/adca/adca_article_chondrodysplasia.htmlDonlinDexters is using a 20% reduction. On a 40 inch non-chondro bull, a 20% reduction would be 8 inches, just as Dr. Cavanaugh's study states. So DonlinDexters took the Dexter standards of maximum 44" bulls and applied a 20% reduction and she came up with this: Bulls Non-BD1: 40-44 inches BD1 (chondro): 31-35 inches Cows Non-BD1: 38-42 inches BD1 (chondro): 29-33 inches I think DonlinDexters did a pretty good job of evaluating the SCIENCE and developing a good scientific approach. Perhaps it's not perfect, but I haven't seen anyone here offer any suggestions for improvements based on SCIENCE. You need to have a more critical eye. What was the sample size? What ages were the Dexters evaluated? How many carriers vs. non-carriers? Also look closely..."Dr. Julie Cavanagh, University of Sydney (AU), discovered the genetic location of the mutated gene and presented her findings at the 2002 International Dexter Congress, and a test followed soon after. Dr. Cavanagh found that when she averaged the heights of the cows and bulls with and without chondrodysplasia that formed her database," What this says is that the survey and numbers were compiled PRIOR to the test being developed. What does this mean? It means that since there was no reliable means of determining which were carriers and which were non carriers, only the most apparent Dexters both in both long legged and short legged by appearance were chosen for the study. This will naturally account for a larger difference than you otherwise may see Further, were full brothers both carrier and non, compared? How about herds or specific pedigrees, which may account for larger differences. I can't imagine the sample size being large enough to draw any kind of reliable statistics and certainly not with the limited genetic diversity that existed in Australia. Upgrading with other breeds has been allowed in the Australian Dexters for some time...were these upgraded non-carrier Dexters included in the study? The presentation of chondro, and for that matter non-chondro, can have considerable variations. You said yourself that the chondro gene would be expressed with larger animals did you not? These upgraded Dexters in Australia certainly carried larger genetics. I could easily select a number of Dexters for a study and come up with similar findings, or I could easily select a number of Dexters and come up with very different findings. The studies must be able to be reproduced reliably, and I doubt a study with a larger sample size, using the chondro test to select a random number of each types, out of a wide variety of pedigrees, would produce the same result. Right now Kirk, you only can look at articles, photographs, and selectively listen to those with whom you agree. Your animals all have very similar pedigrees. You've already proven here and elsewhere you don't have the capacity to consider opposing viewpoints after all. Those of us with daily experience with chondro carriers, horned and polled, non-carriers, and a wide variety of pedigrees have a much better perspective and can speak from real experience. There is nowhere near that difference between our carriers and non-carriers in our herd, many with similar or identical pedigrees,full brothers or sisters both carrier and non carrier. We have DOZENS of each. You are a one trick pony by comparison. |
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Post by cascade on Dec 6, 2014 20:27:20 GMT
1. Finding the chondro gene, meant that the genetics researcher had the ability to test for the gene, but a standardized test wasn't yet available to the public. First, she went to farms with a good range of tall and short cattle. She collected dna samples and recorded the height of each animal and put them in a database (WITHOUT knowing whether they were chondro or non-chondro - that's important in science)... Then, she conducted the DNA tests on each dna sample and loaded the results in the database. Analysis of the data showed that bulls that tested positive for chondro were dwarfed by 8 inches on average. She reported the results and later, the DNA test was made AVAILABLE TO THE PUBLIC.
2. If you read the report, you'll see where it says that there are some individuals and lines that are dwarfed MORE than the 8" average for bulls and some that are dwarfed less than the 8" average.
3. Not just anyone can do a published peer-reviewed DNA research paper. The genetics expert who did this study had her methods and results reviewed by many other highly regarded genetics experts. It's a rather famous paper because the dexter bulldog deformity was used in genetics discussions by genetics experts for a long time before the test was developed.
4. I do listen to others. DonlinDexters (a chondro breeder on this board) has won me over with her scientific approach to managing the heights of chondro's and non-chondro's at the same time. Her 20% conversion is brilliant and is consistent with the genetics science. Nobody on this board has proposed a better scientific approach than DonlinDexters.
anyone have a better SCIENTIFIC approach than DonlinDexters? Anyone?
Here's her brilliant 20% approach again.
Bulls
Non-BD1: 40-44 inches (at 3 years)
BD1 (chondro): 31-35 inches
Cows
Non-BD1: 38-42 inches
BD1 (chondro): 29-33 inches
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Post by genebo on Dec 7, 2014 20:59:58 GMT
What a shame! Using the search feature of the ADCA website returns no hits on any of the pertinent phrases or title "Cavanaugh Study" you posted yesterday on this thread. That indicates that it doesn't exist on the ADCA site.
I suspect that you are actually quoting an article that someone else (Carol Davidson?) wrote about the Cavanaugh Study. How about giving us a link to the study you are quoting from?
OR, is it more of the same, like "science tells us". Who is this science guy? Does he live in your imagination?
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Post by Donlin Stud on Dec 9, 2014 0:48:28 GMT
Yes, our self-determined set of height guidelines is based on the 'supposed' 20% difference between the longies and shorties BUT it can only ever be a guide for us as it is well documented that the Chondro gene does not affect every Dexter in the same way. So those shorties who display the extreme MAY have a 20% reduction in overall size had the gene not been present but one would think that if a Dexter can only be determined to have the gene through DNA testing because they display very mild characteristics then they couldn't have been affected by the supposed 20% Our self-determined shorty Heights have to be guidelines for this purpose. There were problems with the Cavanaugh study as the test samples were not identified as definitely being Chondro carriers or not. And as for pure Dexters used in the study.......Well since Australia has had a grade up program from the very beginning of the breeds existence/number recovery here, I can't see how. The study's resulting information should only ever be read as a 'nice to know' but I personally would be very reluctant to ever quote any of it's information as exact - it just couldn't be! There was not enough consideration provided or assessment conducted on the variables. Because of the Australian grade-up program we also need to work hard at strengthening those traits which are the Dexter while eliminating the Angus, Jersey and goodness knows what else. If we have Dexters who are taller than what we personally desire but they physically are more representive to the Dexter breed, then they will be in our breeding program. If we have those who are within our personally set height guidelines, but are far removed from what a Dexter should look like, then again, we need to make an assessment when/if including in our breeding program. Currently there are only 3,100 (give or take a few hundred on either side) 'Australian' registered Dexters and a guess is about the same in non-registered 'Australian pure' Dexters. If you look at these numbers in a statistical sense: A medium sized abattoir processes 1500 animals a day - within 4-5 days, the Australian Dexter as a breed could be non-existent. So while I do post here, our stud's circumstances, and immediate choices are very very different from over your way Just thought I would explain |
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Post by lakeportfarms on Dec 9, 2014 2:16:42 GMT
That was exactly what I thought about both the sample makeup and size Donlin, thank you for confirming this! The only thing that I didn't disagree with Kirk on was that you would be using your best efforts to develop a very nice Dexter herd from the available Dexters there, regardless if they were short or long |
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Post by cascade on Dec 9, 2014 5:01:13 GMT
There were problems with the Cavanaugh study as the test samples were not identified as definitely being Chondro carriers or not. And as for pure Dexters used in the study....... The Cavanaugh study was conducted using scientific principles. The animals studied, were first selected and measured and loaded in the database without knowing their chondro status (that's important for studies to NOT know the status ahead of time). Then, the animals were chondro-tested and definitely identified as chondro-carriers or not and the results were loaded into the database. When the animals' heights were averaged by TESTED carrier or not, the chondrodsyplastic dwarf bulls came in 8 inches shorter than normal bulls and the chondrodysplastic dwarf cows came in 5.5 inches shorter than the normal cows. Cavanaugh only studied animals from Dexter breeders that were breeding animals identified as Dexters. If there were animals with impurities, they would have been just as likely to be in both the carrier and non-carrier groups and that would have made little or no impact on the results. |
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Post by jamshundred on Dec 9, 2014 5:16:46 GMT
Kirk,
The modern Australian herd is predominantly a graded-up herd! Do you think the introgressed heights and bone structure of the crossed animals magically disappear?
Judy
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Post by cascade on Dec 9, 2014 20:18:12 GMT
Kirk, The modern Australian herd is predominantly a graded-up herd! Do you think the introgressed heights and bone structure of the crossed animals magically disappear? Judy 1. Grading-up, starting with a breed that's closely related to dexters, and using a pure Dexter bull over and over and over and over and over, and selecting for traits that are the most "Dexter-like" does indeed create dexters that are just as "pure" as any typical dexter, maybe even MORE pure, in the hands of a skilled breeder. On the other hand, another breeder could start with certain fully "traditional on paper" dexters and come back in 5 generations with some very non-dexter looking and non-dexter behaving animals if that's what they selected for. The ONLY thing that keeps dexters looking and behaving like dexters through the generations is selection for dexter traits of small, friendly, dual purposed, and appropriately colored - generation after generation. 2. Nearly every gene found in other breeds can be found in dexters and nearly every gene in Dexters can be found in other breeds... The only difference is frequency of genes in the herd as a whole. For example, the Dun gene is quite common in Dexters, but you can bet that it's in Angus in very very low frequencies. 3. The Cavanaugh study was looking at the impact of the Chondrodysplasia gene on cattle. The chondro gene has VERY similar effects on ALL breeds of cattle. Cavanaugh limited her study to animals identified as Dexters. The animals in the study that ended up testing positive for chondro were just as likely to have some "impurities" as the ones that tested negative, so the "impurities" wouldn't matter to the study. 4. The study found an 8" average difference between chondro-dwarf and non-dwarf bulls and 5.5" difference between chondro-cows and non-chondro cows. 5. The four largest bulls in the AI catalog are non-chondro traditional horned bulls (with no saltaire platinum). They are 48" +....... It's easy to imagine that if they were bred on chondro cows, you could get some 40" chondro-dwarf sons. Because the gene affects larger animals more than smaller animals, a percentage figure is more realistic... A chondro breeder on this board is using a 20% average reduction figure.... perhaps it should only be 18% or 16%.... On AVERAGE, in your opinion, what percentage reduction can you expect from the chondro-gene? |
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Post by wvdexters on Dec 9, 2014 22:15:13 GMT
1. Grading-up, starting with a breed that's closely related to dexters, and using a pure Dexter bull over and over and over and over and over, and selecting for traits that are the most "Dexter-like" does indeed create dexters that are just as "pure" as any typical dexter, maybe even MORE pure, in the hands of a skilled breeder. Huh?? |
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Post by lakeportfarms on Dec 10, 2014 1:19:05 GMT
That's funny Karrie. I had to do a double take of that myself!
And that folks, sums up the thought process of the breeders who have tailored their herds to polled, red, A2/A2 animals, with homozygous polled being the most important factor now followed closely by A2/A2. They are certainly not being selected for "Dexter like" appearance!
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? Is that what it is this week Kirk?? I had no idea. We'll have to remember this bit of information. Oh, if only it were fact. (As it is being represented here. Or should I say misrepresented??) Anyway .... I thought it was 8 in another post you made. And I remember reading 3 or 4 to 7 being the "magic numbers" before this. I gotta say though, it's definitely going up!!!! LOL
