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Post by jamshundred on Sept 3, 2014 4:48:26 GMT
Donlin,
Thought you might be interested in this. It also dovetails with my early comments on scientists developing tests and recording patents on them. I notice Dr. Beever is the researcher here in the US ( chondro and PHA).
It took more than TWENTY years for the PHA that was imported to Canada via the Woodmagic herd in 1978 to become so widespread that research began and nearly 30 years before there was a patent and a test.
THE CLOCK IS TICKING. . . . . . . TICK. . . TOCK. . . . TICK. . . TOCK. We have a bull whose semen was imported in 1994. Only Twenty years ago. This bull has FOUR outcrossings in his 10 line pedigree where one parent is UNKNOWN. Just known to be a beef breed ! ! Is there a single soul or scientist that can say there are no genetic recessives for new defects lurking in this pedigree?
The below was reported out of Australia. . . but I don't think it is anything necessarily new. Maybe the quest for patent is the newness? I saw reports in the US of this affliction in Holsteins in 1993. It is in humans too.
Judy
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Post by wvdexters on Sept 3, 2014 14:24:39 GMT
Very interesting. This reminds me of a case I saw last year on the tv show Dr. Pol. The vets were called out to a dairy farm in Mich. Holstein calf was extremely bloated and in pain. After examining Dr. Pol diagnosed that the intestines were not connected properly to the rectum and that the calf was unable to pass any wastes. He was eating fine in the beginning but basically just "filled up".
When they did a post-mortem you could plainly see the "end" of the intestine and how it had developed with no connection to the rectum. The calf had no chance of survival. I remember him saying that this was something they were seeing more of but I don't think he knew the cause.
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Post by cascade on Sept 28, 2014 8:04:07 GMT
Lethal Genetic flaws like PHA and Chondro and others are very easy to find in short order. Simply breeding a bull back on his own daughters or other forms of close line-breeding will quickly uncover genetic flaws when dead calves start showing up. PHA was "discovered" (malformed calves were encountered) long ago, but because folks were used to seeing and living with dead malformed calves from Chondro, when they had dead malformed calves from PHA, they just swept them under the rug instead of investigating. It can take years of DNA study to locate the actual lethal genes on the chromosomes, but the dead calves show up very quickly. I'll guarantee that the bull "imported in 1994" does NOT carry any lethal genetic flaws because that bull has been used heavily in line-breeding (on both sides of many, many pedigrees), with no observed problems.
It's important to understand that genetic defects don't just come from imports, instead, they come from MUTATIONS (copy errors in genes). Every animal, imported or not, can be the source of problem mutations. Before bulls are offered for wide-spread AI use, they should first be bred back on 20 or more of their own daughters and the pregnancies and calves should be carefully tracked and observed. Until a potential AI sire undergoes this daughter testing, they should be listed as "Experimental, Risky, Untested Sires" and NOT advertised for widespread usage.
It's ironic that many folks shun inbreeding, but inbreeding does NOT cause genetic problems. Inbreeding just helps uncover existing hidden genetic problems.
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Post by lonecowhand on Sept 29, 2014 20:06:17 GMT
Cascade, Apparently you like that Phrase "Lethal Genetic Flaws" when referring to the chondro condition. I'm sure you know these words are both erroneous and inflammatory, so I assume you are doing it on purpose to elicit a response.
I'm also sure you have read the other folks posts defending the condition, so you know this is personal.
The condition you are referring to is the reason that there are Dexters at all , if it weren't for the dwarf gene , you would not have any short pleasant animals from which to breed. You would have started and finished with Kerries, which are well proportioned animals but not Dexters.
You could drop the vitriol, and enjoy the pleasant commeraderie of others like yourself that do enjoy the breed, and the sharing of experience and information.
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Post by jamshundred on Sept 29, 2014 20:45:14 GMT
Kirk
I have never in all my Dexter years heard so many cases of dead and pulled calves as I have this year and all but one were reported by breeders owning polled. Something IS amiss!
Judy
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Post by cascade on Sept 30, 2014 0:08:45 GMT
Cascade, Apparently you like that Phrase "Lethal Genetic Flaws" when referring to the chondro condition. I'm sure you know these words are both erroneous and inflammatory, so I assume you are doing it on purpose to elicit a response. I'm also sure you have read the other folks posts defending the condition, so you know this is personal. The condition you are referring to is the reason that there are Dexters at all , if it weren't for the dwarf gene , you would not have any short pleasant animals from which to breed. You would have started and finished with Kerries, which are well proportioned animals but not Dexters. You could drop the vitriol, and enjoy the pleasant commeraderie of others like yourself that do enjoy the breed, and the sharing of experience and information. "Genetic Defect" and "Lethal Gene" are the scientific description of defective genes that cause Chondro and PHA. NOT ERRONEOUS at all. Just honest science. calfology.com/library/wiki/dwarfism-condrodysplasiaThe founders of the Dexter breed took shortcuts to get "instant" small cattle, but that shortcut often proved ineffective 50% of the time, and/or fatal 25% of the time. But their flawed attempts helped get us started with the idea establishing a small breed of cattle using Kerry cattle as a source and I'm thankful for that, just like I'm thankful for all the flawed attempts that computer designers made to help us arrive at the great computers we have today. Beryl Rutherford of the Woodmagic herd showed that through pat hard work and good honest selection, you can breed 100% friendly small cattle without the lethal gene. I enjoy sharing that good news. I enjoy genetics and like to discuss it honestly and scientifically. |
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Post by cascade on Sept 30, 2014 3:28:10 GMT
Kirk I have never in all my Dexter years heard so many cases of dead and pulled calves as I have this year and all but one were reported by breeders owning polled. Something IS amiss! Judy While PHA and Chondro are lethal genes and have a direct genetic linkage to dead calves, there is NO direct genetic linkage of horned status to problem calves. We've bred about 120 polled calves (by simply putting a single bull in with our entire herd of cows) and only had to help with two of the calves over the past decade (one was breech). All the rest were born outside on pasture in all sorts of terrible weather (including pounding freezing rain) with no assistance. We just go out and see the moms with new calves and put a tag in their ear. Most all of our calves hit the ground running. We like to select for reasonable birth weights, not too small (because they're too weak) and not too large (because of possible birthing problems)... Low birth weights (in humans and cows) can be just as problematic as large birth weights. We used a new first-time bull this past year (Cascade's Goldrush) and he gave us nearly 20 robust calves, outside in much bad weather, with no assistance or shelter at all for any of them. Ongoing selection for BOTH easy birthing AND robust calves is critical. Anyone having excess problems due to too large of calves or too weak of calves or deformed calves needs to make adjustments and better selection choices and consider culling problem animals. |
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Post by lakeportfarms on Sept 30, 2014 10:30:22 GMT
Kirk, your statement about small calves not being robust is simply not true with respect to chondro carriers. Though our average is around 29 lbs., our 23 lb chondro calves that we have had (out of non-carrier cows even) have been at least as if not more robust than the larger calves born on our farm, and we've had quite a few of both carrier and non-carrier. Have you had a large number of chondro carrier calves??? I didn't think so. Chondro carrier calves (and cows and bulls) also tolerate our cold snowy weather better than the non-carriers, though I will say they need their carrier friends to make the paths in the deep snow from time to time.
I know of a herd with 20% of their calves out of a homozygous polled bull that have had to have c-sections in this past calving season, with 65 plus lb. heifers on both occasions. Our only calving problem ever was with a heifer that we purchased bred, who had been with a polled bull. That heifer also attempted (unsuccessfully though we saved the heifer) to deliver a 65 lb. bull calf. That isn't normal.
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Post by cascade on Sept 30, 2014 17:23:44 GMT
Kirk, your statement about small calves not being robust is simply not true with respect to chondro carriers. Though our average is around 29 lbs., our 23 lb chondro calves that we have had (out of non-carrier cows even) have been at least as if not more robust than the larger calves born on our farm, and we've had quite a few of both carrier and non-carrier. Have you had a large number of chondro carrier calves??? I didn't think so. Chondro carrier calves (and cows and bulls) also tolerate our cold snowy weather better than the non-carriers, though I will say they need their carrier friends to make the paths in the deep snow from time to time. I know of a herd with 20% of their calves out of a homozygous polled bull that have had to have c-sections in this past calving season, with 65 plus lb. heifers on both occasions. Our only calving problem ever was with a heifer that we purchased bred, who had been with a polled bull. That heifer also attempted (unsuccessfully though we saved the heifer) to deliver a 65 lb. bull calf. That isn't normal. I didn't say all small calves are not robust.... I said TOO SMALL of calves might not be robust enough to be born outside in terrible weather, with no shelter and no assistance. I think we both agree that both TOO small is a problem, and TOO large is a problem, and that's the case in all animals including humans. Continued selection for too small or too large, can lead to problems. One thing to keep in mind with too large of calves, is that the bull is only half of the equation. A 65+ pound problem calf likely got some of its size from the mom's side, not just the bull's side. Another thing to keep in mind, is that if you over-select for small calves, you may also be unintentionally selecting for moms who can't handle normal sized calves. A cow that has a hard time passing a 50 pound calf can be problematic. AGAIN, There is ZERO genetic connection between large calves and horn status. Horned breeders can over-select for giant animals and giant calves just as easily as a polled breeder can. Polled breeders can select for tiny animals and tiny calves just as easily as horned breeders can. The giant calves in your examples have NOTHING to do horn status. I'd cull both the mom and the unborn calf before I'd do a c-section (and I'd likely cull the bull too if he was throwing 65+ pound calves). If ANY dexter bull (horned or polled or black or red) is regularly throwing 65+ pound calves, he should be immediately culled along with any bulls carrying lethal genes (in my humble opinion). |
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Post by lakeportfarms on Sept 30, 2014 18:28:20 GMT
In the case of one of the heifers, her sire was sired by Hedgehog III, and she herself was not very large. Now, on her dams side there were polled genetics, so perhaps the large size gene was hidden and lurking in her through her dam's pedigree, waiting for a trigger to come out. And bred to a polled bull may have been the trigger for the gene to spring up and produce such a large calf, fooled into thinking that the heifer was physically larger than she actually was. I suspect you continue to dispute that polled Dexters were from Angus or another polled breed outcross, and that it has always been a fresh mutation.
But you also contradict yourself...you state that frequent line breeding (which is heavily present in most polled lines, and out of ONE bull, Saltaire Platinum) will uncover hidden traits, and then you refuse to accept that high calving weight in calves may be one of those hidden traits! Isn't it also possible that since polled Dexters were in such high demand for a while, that some unscrupulous breeders could have used other breeds mixed in with their Dexters to increase the odds of having polled "Dexters" to sell? I could get a grade something...Angus, whatever, polled, as long as it was black, and if I used Saltaire Platinum semen on her... VIOLA!... I have a polled "Dexter" that could be registered. All I have to do is take a registered Dexter and say she was the dam, even one that is on my dinner plate right now, but not reported as deceased. Which would also lead to higher calving weights. Angus have no problem with 65 lb calves, in fact they are known as an easy calving breed with 65 lb calves. That isn't the case for the Dexter, except in the very largest examples of Dexter, which, from my observation, are most frequently found in the polled varieties.
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Post by lonecowhand on Sept 30, 2014 18:35:10 GMT
Cascade, We all enjoy genetics and like to discuss it honestly, but there is a difference between honesty and deliberate provocation.
Your denial of the polled/big calf connection reminds me of Big Tobaccos' denial of a connection between smoking and cancer.
You are right that the absence of horns does not cause problem calves, it's the genetic baggage (alleles) that came along in the outcross with a large beast.
If you cross your Great Dane and your Chihuahua, you may get some small Danes, but sooner or later you will get some Great Wah-wahs!
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Post by Donlin Stud on Sept 30, 2014 20:00:41 GMT
Hi Judy
Yes I did read about the Angus issue and some more about it's affliction in other breeds too.
Your right, it's not a new issue but is becoming too frequent in the Angus.
My two -bobs worth on the above matters - Line / in breeding doesn't cause issues, it brings them to the surface allowing for a cleansing of bloodlines while quickly establishing desired conformation etc.
If we don't want to know what is lurking, then don't look. Keep ones head in the sand instead because that makes perfect sense - not !
The Chondro and PHA gene itself is NOT lethal.
Only when paired will these genes stop or inhibit to an extent, what is deemed normal development
The dexter breed is attractive because of the dwarfs.
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Post by cascade on Sept 30, 2014 21:41:19 GMT
In the case of one of the heifers, her sire was sired by Hedgehog III, and she herself was not very large. Now, on her dams side there were polled genetics, so perhaps the large size gene was hidden and lurking in her through her dam's pedigree, waiting for a trigger to come out. And bred to a polled bull may have been the trigger for the gene to spring up and produce such a large calf, fooled into thinking that the heifer was physically larger than she actually was. I suspect you continue to dispute that polled Dexters were from Angus or another polled breed outcross, and that it has always been a fresh mutation. But you also contradict yourself...you state that frequent line breeding (which is heavily present in most polled lines, and out of ONE bull, Saltaire Platinum) will uncover hidden traits, and then you refuse to accept that high calving weight in calves may be one of those hidden traits! Isn't it also possible that since polled Dexters were in such high demand for a while, that some unscrupulous breeders could have used other breeds mixed in with their Dexters to increase the odds of having polled "Dexters" to sell? I could get a grade something...Angus, whatever, polled, as long as it was black, and if I used Saltaire Platinum semen on her... VIOLA!... I have a polled "Dexter" that could be registered. All I have to do is take a registered Dexter and say she was the dam, even one that is on my dinner plate right now, but not reported as deceased. Which would also lead to higher calving weights. Angus have no problem with 65 lb calves, in fact they are known as an easy calving breed with 65 lb calves. That isn't the case for the Dexter, except in the very largest examples of Dexter, which, from my observation, are most frequently found in the polled varieties. 1. There is no such thing as a "large calf gene" that can get passed down many generations. Instead, larger calves is a highly polygenetic trait. A large calf is the result of the combination of many, many different genes (and some environmental factors too). The only way that polygentic traits get reliably passed down for many generations is by constant selection for those same traits. If some lines have larger calves, it's because breeders have selected for that trait (intentionally or unintentionally) 2. EVERY Dexter including the most "traditional" of dexters has scores of non-dexters in their distant backgrounds. Today's pedigrees and registries do their best to keep external animals out, but ongoing selection for the key dexter traits of small frames, dual purpose, easily-managed friendly cows and bulls, is what keeps dexters as dexters. 3. Many polled breeders tend to select animals for solid frames and excellent cattle conformation (as opposed to "little pet-cow" conformation). It's possible that they've accidentally selected for larger calves, but those larger calves would have NOTHING to do with the polled gene. There is ZERO connection between the polled gene and calf size. 4. Any polled dexter breeders that wish to breed for smaller frames and smaller calves, can easily do so. |
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Post by cascade on Sept 30, 2014 22:15:46 GMT
The Chondro and PHA gene itself is NOT lethal. Only when paired will these genes stop or inhibit to an extent, what is deemed normal development The term "Lethal Gene" or "Lethal Allele" is a well known genetic term. Chondro and PHA are both lethal genes by definition. " Alleles that cause an organism to die only when present in homozygous condition are called lethal alleles. The gene involved is considered an essential gene.
When Mendel's Laws were rediscovered, geneticists believed that mutations would only alter the appearance of a living organism. However, it was discovered that a mutant allele could cause death. When an essential gene is mutated, it can result in a lethal phenotype. If the mutation is caused by a dominant lethal allele, the heterozygote for the allele will show the lethal phenotype, the homozygote dominant is impossible. If the mutation is caused by a recessive lethal allele, the homozygote for the allele will have the lethal phenotype." en.wikipedia.org/wiki/Lethal_alleleIn the case of PHA, one single gene does NOT inhibit normal development because it is fully recessive. In the case of Chondro, one single gene DOES inhibit normal development (and causes dwarfism) because it is NOT fully recessive. |
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Post by lonecowhand on Sept 30, 2014 22:23:51 GMT
Wait ,
So, No. 1) you don't agree that a bull can have an effect on small calf size, or you do agree, but they can't have an effect on large calf size?
I don't agree with No.2,"scores of non-Dexters",unless you mean Kerries, from whom the dexters were selected.
No. 3) If you mean polled breeders are selecting for Angus, then I agree with that. Are you one of those that believe that the polled gene miraculously appeared?
If you agree it's possible to accidentally breed for larger calves, then I'm asserting that's what came along with the polled trait.(by accident)
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Post by lakeportfarms on Oct 1, 2014 0:20:29 GMT
3. Many polled breeders tend to select animals for solid frames and excellent cattle conformation (as opposed to "little pet-cow" conformation). It's possible that they've accidentally selected for larger calves, but those larger calves would have NOTHING to do with the polled gene. There is ZERO connection between the polled gene and calf size. Hahahaha....Obviously I've hit a nerve....They didn't select for polled status at all??? Why is it that so many polled breeders sell off their horned offspring then to unsuspecting buyers, who sadly end up with a horned bull or cow out of polled genetics? You mean that none of these horned bulls or cows had any worthwhile attributes that compelled those polled breeders to keep them? Polled breeders are probably the best and yet at the same time the the worst example of single trait selection. And I would say the the larger calves came from the repeated selection for single trait selection of polled bulls and cows, and not by accident. And if anybody has been advocating for little "pet cows", it is those that continue to push the Dexter as a "miniature" breed, and ignore the ability of a chondro cow to outproduce herself many times during her productive years with steers that wean at nearly the same or even taller height as their dam, and between 80-100% of the dam's weight depending on when he is weaned (and we wean at 10-11 months). |
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Post by cascade on Oct 1, 2014 6:24:27 GMT
Wait , So, No. 1) you don't agree that a bull can have an effect on small calf size, or you do agree, but they can't have an effect on large calf size? I don't agree with No.2,"scores of non-Dexters",unless you mean Kerries, from whom the dexters were selected. No. 3) If you mean polled breeders are selecting for Angus, then I agree with that. Are you one of those that believe that the polled gene miraculously appeared? If you agree it's possible to accidentally breed for larger calves, then I'm asserting that's what came along with the polled trait.(by accident) 1. Of course bulls (and cows too) have an effect on calf size (large or small) but it's not via a single "Size Gene" that can come down through the generations. Instead, calf size (especially in non-chondros) is due to a combination of many genes in certain combinations. Those combinations can't be easily passed from a distant ancestor the way a single gene (like color or polledness) can be passed from a distant ancestor. 2. Kerries too, had scores of Non-Kerries in their backgrounds. Traveling bulls were a regularity with few fences to stop them. 3. In the early going, Polled breeders tended to be professional cattle people who selected the very best and most robust and highly conforming dexters (instead of backyard pet-quality dexters). The unintended consequence of this, could be larger robust calves... That's not necessarily a bad thing as long as the mothers are robust cows. But when these excellent polled bulls are used on smaller girls in other herds, it could be a problem. But this is easily corrected by polled breeders who focus on bringing down calf size and select for polled bulls that throw smaller calves. I'm certainly working on this in our herd. 4. Polledness is not a miracle, it's DNA science. Polledness is due to mutations that regularly occur in all breeds of cattle. Mutations are simply copying errors in the DNA replication process. Polled cattle mutations have been PROVEN to occur. 5. I'm saying that larger calf size is INDEPENDENT of horn status and polledness, and smart polled breeders can reduce calf size (and adult cattle size too) via ongoing selection and culling. |
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Post by Deleted on Oct 1, 2014 10:58:52 GMT
Now I am new to Dexters but not new to purbreed animals. A polled animal is a
mutation and while still considered a purbreed would be a disculified (novelty)
animals in most species just like a white Dexter (see the other board). My opinion is
that most species that condone this as registered purbreed animals sooner or latter
have so many varieties of the animal that it is almost detrimental to them. As always
with us humans it will usually follow the money too.
My understanding of A D C A handbook
1. Bulls 3 yr. and OVER should not exceed 1000 lbs.
2. 44"max. and 38" min. at three years. This one seems very open to abuse. How is
it controlled?
3. Cows three years and Over 750 lbs
4. MATURE cows 42" max 36" min.
AND now my bomb shell
5. HORNS These shall be moderately thick springing well from head, with an
inward and slightly upward curve. Removal of horns is allowed without penalization.
I understand removal to mean to physically alter not a mutation.
6. No where in the hand book guidelines does it discourage condo or pha they both seem
to be addressed as issues whit the breed and it gives breeding practices for this.
I have come to understand that the Dexter and Kerrie breeds were one at one time and
there is not one thing to be done about that. But both were what I call survival cattle
for both there survival and human survival. People actually had these cattle in there
homes or a stall attached to there home. So I would believe even a 750 lbs. cow could be
a issue.
(
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Post by lakeportfarms on Oct 1, 2014 11:15:31 GMT
Kirk,
Oh geez... I guess I'm going to have to start referring to Saltaire Platinum as the "Magic Bull", who somehow managed to put together superior confirmation, temperament, (who just happened to be polled), and he provided so much improvement that he attracted "superior cattle breeders" to a rather limited, endangered, and relatively obscure breed (which against all odds happened to develop a polled mutation with so few numbers) to suddenly start to think that rather than a "toy hobby breed" they could compete with the other "real cattle" out there and be taken seriously for a change. Give me a break.
More likely it was the thought that they could take advantage of the "toy hobby breed" reputation of the Dexter, and make it even better so the toy hobby breeders didn't have to mess with horns. The toy hobby breeders would beat a path to their door, and they could make boatloads of money just like the early adopters in the Alpaca, (insert name of latest livestock fad) etc...did. I've seen Alpacas free to a good home lately on Craigslist. Not that cattle will reach that point ever, even the most linebred polled Dexter has beef value, but have you looked on the ADCA site lately at all the polled Dexters for sale, especially the bulls? I'd dare say there haven't been many culled polled Dexters out there, and homozygous polled bulls are almost always assured of not being steered. If I were a Dexter bull today, I'd want to be born homozygous polled, that's for sure!
I never said there was a single gene responsible for high calving weights. And since breeders who select for polled tend to try to keep a polled herd, it's a lot harder to break out and eliminate the combination of genes that produce such large calves. Read what I wrote again, it was a HOMOZYGOUS polled bull bred to a small horned Dexter who also had polled genetics combined with small Hedgehog genetics. Basically 3/4 of the pedigree is polled with the resulting calf only alive through extraordinary measures, as is the dam, who would have died calving. Of course your herd wouldn't have so many problems, because you cull so many problem Dexters right?
As others have said, we've been through this before...Lonecowhand is exactly right. This isn't informative, it is designed to be provocative and agenda driven.
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Post by cascade on Oct 1, 2014 17:30:52 GMT
5. HORNS These shall be moderately thick springing well from head, with an inward and slightly upward curve. Removal of horns is allowed without penalization. I understand removal to mean to physically alter not a mutation. It says "Removal of horns is allowed" and makes no mention of the method. I understand horn removal to mean via the most humane way possible, or not done at all. The polled gene is the most humane way to do it. Physical dehorning can be terribly painful to animals and result in infection. Some places are considering making physical dehorning illegal. We did physical dehorning once 10 years ago with a vet and I'll never do it again, it was awful. Our sweet dexters are very happy that we use the gene to dehorn them, instead of acid or extreme heat or sharp metal gouging. Six years ago, in order to bring down the size of our non-chondro herd, we selected a shorter son out of our non-chondro homozyous polled A2/A2 bull, and he happened to be heterozygous polled, so we got a few horned calves for a couple of years. We kept the horns on. I wouldn't want an entire herd of horns, but I don't mind one or two. I'm glad some people like horns, I like to see pictures of horned dexters, especially the bulls. In our herd, we're back to a homozygous polled A2/A2 bull now and we continue to work on bringing size down with great success. PS. Remember, I'm on your side.. Dexters need to be maintained as a small, friendly, trouble-free, safe, and easy-to-manage breed. The polled gene sure makes dehorning a non-issue and makes our cattle safer. |
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Post by jamshundred on Oct 1, 2014 19:39:16 GMT
ANOTHER! ! dead calf reported on a FB group. Something is wrong! ! I've been breeding Dexters for over 20 years and at one time had more than a few dozen Dexters in the herd. I've never had a non-bulldog calf born dead or die after birth. I've only had one Dexter calf that had to be pulled, it was a 19 year old cow and I think the vet caused that problem. I've lost a few healthy calves over the years to freakish accidents but not to birthing issues. I am perplexed. There have been constant reports this year of calves being pulled and dead calves. THIS IS NOT DEXTER-ish! The owner has not the time to have the calf checked for cause of death although it seems likely an extended labor could have been responsible.
If P&G had a REAL purpose it would be to contact owners who report these incidences and offer advice on having a necropsy and even have a slush fund to help subsidize them. It is NOT normal for Dexters to have the calving issues that are being reported and the leadership of the breed should ask for owners to report dystocia births and encourage necropsy when death is involved and follow-up with owners.
Judy
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Post by lonecowhand on Oct 1, 2014 20:26:29 GMT
P&G?
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Post by cascade on Oct 1, 2014 20:45:31 GMT
since breeders who select for polled tend to try to keep a polled herd, it's a lot harder to break out and eliminate the combination of genes that produce such large calves. Read what I wrote again, it was a HOMOZYGOUS polled bull bred to a small horned Dexter who also had polled genetics combined with small Hedgehog genetics. Basically 3/4 of the pedigree is polled with the resulting calf only alive through extraordinary measures, as is the dam, who would have died calving. Of course your herd wouldn't have so many problems, because you cull so many problem Dexters right? The problem you encountered had nothing to do with the polled gene. You had a small dam (with both small genes AND larger genes in her background), and you bred her on a bull with larger genes. The bull's larger genes, happened to match up with some of the dam's hidden larger genes and produced an exceptionally larger calf, too large for the small mom to handle. I'm not encountering this problem in our herd because we're moving slowly and we're not using larger bulls on smaller females, but doing it the other way around. If you want to breed for smaller polled (or horned) animals, then you need to use smaller bulls on larger dams, not smaller dams on larger bulls. PS. I don't think we're disagreeing all that much because we both have the same goals of small, friendly, easy, productive Dexters. |
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