Where does the White come from?

[marion]

Hi Clive, It's the same PHA we were discussing in May, under the General thread 'The high cost of breeding cattle'.
You can read about PHA on the ADCA site. Here is the link:

www.dextercattle.org/genPHA.htm

marion

[liz]

Gene where are you getting your information? You are speaking as an authority on this subject but boy have I ever had different information. PHA mutation in Dexters is not the same at all as the PHA mutation in other breeds, I believe it is actually located at a different chromosome, but perhaps someone with a lot more genetic expertise than you or I, could chime in here. Just a word though, Pulmonary (lung) Hypoplasia (underdevelopment) with Anasarca (filling with fluid) is the condition, not the gene or series of genes that could cause it.

A genetic mutation, once it has occurred in any living organism has a 50% chance of being passed to the offspring every time that it replicates itself, (mates in cows). That is called Mendelian genetics.... although I am aware there could be other considerations in the math, like 'epigenetics'.

Priapus' ancestors, are dead but his sire Trillium Cluny, pure Woodmagic genetics, tested free by semen testing, so any reference to him having possibly inherited the gene could only be through his dam, Wheatear, who also had some Doesmead genetics. As we know, Woodmagic herd has been closed and heavily line bred, Beryl was very concerned about the introgression of other breeds into Dexters, so I find it a bit incredible to believe that a breeder of 50 years who spent her life and herd eradicating Chondrodysplasia, without introgression would look for new bloodlines in any place where it could be a question. Just my opinion of course.

Australia and New Zealand started this investigation a long time before we, in North America got involved. Kudos to all of those who have and are actively involved in the researching of the link in the PHA battle, Judy, Patti, John and Carole to name just a very few.

Finally, again Gene you speak as an authority about the polled mutation coming from an 'intrusion' of Angus yet I think that you are wrong, and really your opinion is not authority on this subject but conjecture. I think that with our recent discovery of the gene causing the PHA mutation in Dexters that it should be an example that other mutations have and will occur.

Liz

[kansasdexters]

Hi Liz,

The PHA mutation in Dexter cattle occurs on Chromosome 6, the same chromosome as the PHA mutation in other breeds (Shorthorn, Maine-Angou, Chianina, etc.).

What makes the Dexter PHA mutation different, is that it is the result of a greater number of base pair deletions within that particular gene located on Chromosome 6. Thus, it affects the same gene on the same chromosome and the end result is the same: an allele that does not function properly. The only difference is in the number of base pair deletions.

Genebo has a very interesting thought concerning the polled mutation. (Please note that the polled mutation occurs on Chromosome 1 in cattle.) Genebo's idea that polledness in different breeds may be the result of a slightly different mutation within the same gene that becomes a "polled" gene is quite thought provoking. Like PHA, it would occur within the same region on the same chromosome -- but it might actually be a unique mutation such as the deletion of more or fewer base pairs, or possibly the transposition of a base pair or series of base pairs. Because it occurs on the same gene and on the same chromosome it has the same net result of no horn growth. But if we could look at the actual base pair sequence in that specific gene, we might see a difference between the specific mutation in the base pair sequence that results in genetic polledness in Angus, compared with the mutation that causes polledness in Dexters.

Great discussion!

Patti

[liz]

Thanks for explaining the difference with Dexter PHA Pattie, Liz

[Clive]

Have read the article thanks Marion. Also found details of it in shorthorns.

Question: How big is this problem, meaning how many cases have there been recently? Even if you don't know a figures is it loads or just a few?

[kansasdexters]

Hi Clive,

If you look at the Search page of the ADCA Online Pedigree, you will find a search criteria for PHA Status (go to http://www.dextercattle.org) . When I checked it this morning, there were 31 Dexters identified as PHA-carriers (heterozygous for PHA) and 358 Dexters identified as PHA non-carriers (homozygous normal). These are the only PHA test results that have been submitted (so far) to the ADCA registry for public access through the Online Pedigree.

The incidence of actual PHA-affected calves (homozygous for PHA) is probably very few relative to the total number of Dexter calves born each year in the United States. That's due in part to the fact that with a (PHA-carrier x PHA-carrier) mating there is only a 1 in 4 chance of even conceiving a PHA-affected calf, then there is always the possibility that the defective fetus gets sloughed early in the pregnancy and the cow comes back into heat and rebreeds and ends up with a normal calf.

It's the number of PHA-carriers (heterozygous for PHA) that we are trying to determine by encouraging breeders to test. Once a breeder knows which animals in their herd are PHA-carriers, then they can effectively manage the situation and completely avoid ever having a PHA-affected calf or calving related problem.


Patti

[Clive]

Crikey, that's 10% of those reported are carrying the gene. It needs controlling. I suppose that even one bull that was used a lot by AI or naturally could start the problem because his offspring might carry it down through the generations and then come back on themselves when they eventually meet their long-distant relatives.

We've had a classic bulldog but never a PHA (yet!).

I also wonder if, like chondro, PHA-carriers (although visually fine) have a downside even though not lethal? Is there any evidence that you know about, such as restricted lungs or whatever. I would be willing to have my bulls tested and any breeding cows (that are not being used just for beef production) which is only a few.

From my point of view it would be buyer beware and although I never buy in, I would now insist on a test if I was.

[cddexter]

Gene, I just have to comment. "The bull which brought polledness to the US Dexter herd has Angus in it's pedigree. There's no surprise where the polledness came from." Not so. PLEASE do better research before you spout off as though an expert. There is reported to be angus back there, but the line descended from that was horned after the first generation, not polled, so it couldn't have come from that source.

You also say, "It's also possible that PHA came to Dexters by an intrusion from the other breeds and mutated slightly once here. This is more likely." However, the s/h, m/a mutation is at the front of the string, and is from three missing base pairs; the Dexter mutation is much further along the string, and is from 84 missing base pairs: no connection at all.

There is the ability to check behind Priapus; it's in abeyance until easier checking has been completed, and that's waiting on hair tests. Since Igenity did have trouble with color testing, there are some who are concerned about their accuracy with pha. I think there is a move afoot to wait for pfizer, where the quality of the results is less in question. Patti posted somewhere she'd cross checked one animal and got the same results and that proof was good enough for her. It's not good enough for others, thus the wait.
regards, c.

[cddexter]

hi gene, I did post earlier, but I guess it got lost somewhere. I always like you when you are in your courteous gent mode. Don't worry about stepping on my toes--didn't happen. My only involvement with Platinum was helping Fred find choices in England, and trying to keep the record straight here when things got too far out of whack. Platinum was accused of having Angus back there, but I'm sure you remember polled is a dominant gene, and since it was bred out after the first generation, he could be all the Angus you want, and he still would not have inherited polled from that source.

I have to disagree about levels of accuracy. I spent time with Julie and have seen the dna strand comparisons, and there's no mistaking a normal gene from a chondro-affected gene. I don't know enough about pha, but having a huge bite of dna missing from the 'sentence' would have to be pretty obvious, I'd think.

Wonder what they'll turn up next? regards, c.

[littlecowfl]

How unusual! I think it would be good to have a limited registry for excess white, meaning, they could be registered but their offspring would not be. That way, we could keep track of how many actually crop up.

I keep thinking about piebald deer because the coloration is similar. Tell me, is she line bred? Just a thought, not a criticism.

Here are piebald deer, for those not familiar:

www.pwrc.usgs.gov/history/whitedr.htm

cjpineridgewhitetails.com/aboutus.aspx

[kansasdexters]

I've been doing some reading today and ran across this little gem on p. 96 from W.R. Thrower's book, "The Dexter Cow and Cattle Keeping on a Small Scale", published in 1954:

"The Dexter Cattle Society was formed in England in 1900, and a herd book started has now entirely superseded that kept by the Royal Dublin Society dating from 1890. Volume I of the Dublin book contains the entry of a white Dexter cow, Lily 2nd (#126) calved 1887, owned by the Earl of Rosse and described as being "white with a very little red", which is interesting, because to-day in western Ireland are many Dexters with a lot of white about them, but probably the result of Shorthorn-Dexter crossing".

W.R. Thrower goes on to say: "The purpose of the herd book is the same as that for any breed, namely, to provide a permanent record of the best animals. The progeny of dams and sires already entered in the herd book will be accepted annually for registration without question. To gain entry without full birth qualification is difficult, and before such entries can be accepted a full investigation is made into the pedigree of the beasts, as far as this is known, and they are carefully examined for conformation and other points by an inspector of the society. If approved for provisional admission to the herd book these animals are listed in the Appendix and by a graduation process through this Appendix of each successive generation of progeny full herd book status is finally attained."

We know that many years later, when Parndon Charley Pudding (the sire of record for Parndon Bullfinch) was bred to Channel Island cows (Guernsey and Jersey cattle may carry or be homozygous for recessive white spotting), some of the resulting progeny had white spots. That was the basis of the claim made by Andrew Sheppy that Parndon Charley Pudding had "introgressed genetics" and could not possibly be a purebred Dexter. The white spotted offspring produced when Parndon Charley Pudding was bred to Channel Island cows was the basis of Mr. Sheppy's "proof" of that claim. The rumor mill took this tidbit and ran with it.

We also know that when Parndon Bullfinch semen was used on Holstein heifers (the Holstein breed is homozygous for white spotting) and one of the cross-bred offspring had white markings, and this information was published by Daisy Moore in the Feb. 1969 ADCA Bulletin: "The first offspring of Bullfinch, the Dexter sire supplying semen for artificial insemination, arrived early this month and are the subject of much interest. Two Holstein heifers were bred to Dexter last April by Mr. Harry Campbell of Sharon Springs. Both heifers conceived with the first service and the resulting calves were a heifer and a bull calf. One of our members, John B. Elkan writes to say -- I have purchased both calves to see what growth and progress they will make. The bull calf weighed about 50 lb at birth, the heifer about 65 lbs. Both calves are black, the heifer having a ring or white around the hoofs. One calf has curly hair, the other straight, both have black tongues. They are smart calves and very healthy so far."

So it appears that Parndon Bullfinch carried the gene for recessive white spotting and that he potentially got this gene from his sire of record, Parndon Charley Pudding. Since Parndon Bullfinch and Parndon Charley Pudding didn't have white spots (therefore, they weren't homozygous for recessive white spotting), then Parndon Bullfinch and Parndon Charley Pudding were heterozygous for recessive white spotting, so there was a 50% probability of offspring inheriting this gene and a 50% probability of them not inheriting this gene. A carrier of recessive white spotting can be pure black, with no spots, no white markings. This recessive white spotting gene can be carried for generations before it makes itself known in an offspring that inherits the recessive white spotting gene from both sire and dam.

We also know that recorded in the Volume 1 Herd Book of the American Kerry and Dexter Cattle Club, there are several descendents of the foundation stock imported into the United States in the early 1900's that had white spotting. Therefore the recessive white spotting gene existed in the United States from the beginning of when registered Dexter cattle existed in the United States. Since the earliest days, we've had the potential for producing pedigreed Dexters in the United States with white markings and spots.

When we look at herds that have bred descendents of Parndon Bullfinch with traditional American bloodlines, we see the occurance of recessive white spotting. Here is a link that illustrates several good examples of this (scroll down the page to see the photos): www.thomasdexters.com/index.asp?ID=56

Long story short: Recessive white spotting has been with the Dexter breed since the beginning of pedigreed Dexter cattle.


Patti

[cddexter]

thanks, Patti. Been a long time since I read thrower's book; I'd forgotten that bit. Since you are so good at the details, would you care to extrapolate all that into why Gordonstoun Wellington threw calves with forehead stars, and big white patches all over? You'd swear they were were 100% holstein. Is it because he had Parndon back there somewhere? cheeers, c.

[kansasdexters]

Hi C.

Gordonstoun Wellington, Canada Registered [C186], has Malach's Corey O'Callen in his pedigree, once on his sire side, and twice on his dam's side. Malach's Corey O'Callen was a linebred descendent of Parndon Bullfinch (his sire was Parndon Bullfinch and his dam was a daughter of Parndon Bullfinch).

Since Gordonstoun Wellington wasn't spotted, in order for him to produce white spotted offspring, he had to be bred to cows that either carried recessive white spotting (like he did) or to cows that were homozygous for recessive white spotting (white spotted cows). The Canadian Online Pedigree only shows four registered offspring sired by Gordonstoun Wellington:

Blossom Valley Charlene - C344 & ADCA 4807- Cow - she has 2 registered progeny
Earlona Zelda - C313 - Cow - she has 10 registered progeny
Earlona Zorro - C312 - Bull - he has 6 registered progeny
Manitou Joey - C406 - Bull - he has no registered progeny

Were any of those animals white spotted?? I'm rather surprised that there were two registered bulls sired by Gordonstoun Wellington if it was known that he threw white spotted calves. Especially since these two bulls were born during the time that there was so much criticism of "excessive white" appearing in the Dexter breed. Can you give a bit more background on this??

8/12/2012 Update: I received an email from Australia last night that provided the following additional information:

Gordonstoun Wellington has 263 registered offspring in Australia, about 10% of those male. He died only a couple of months ago, aged 24.

He must have been a very special Dexter bull to have been used so extensively in Australia and loved by his owner for so long.

Patti

[laughingllama75]

Ok.....I know NOTHING about excessive white (except for what I just read). I have a few questions for everyone:

can you reg an animal that has white "patches" or areas
WOULD YOU register one, if allowed
would you even admit to having bred one, and if not.......would you beef it or???

I have a steer that has a white "dash" on his forehead and one on his hip. I got him from a breeder that had a nice little herd of dexters. He was sold as unreg for beef. I steered him, and he is darn cute. An obvious "shortie", he sure is beefing out. I like his color, and I frequently think about what I would do if I had one born here.

[kansasdexters]

People can (and do) register purebred Dexter cattle that have white markings. Here are some examples with photos in the ADCA Online Pedigree:

FF Splash of Paint, ADCA No. 020235
www.dextercattle.org/pedigreedb/ponyweb.cgi?horse=020235&HorseName=Splash&Page=1&Sort=0

CJS Socks, ADCA No. 017194
www.dextercattle.org/pedigreedb/ponyweb.cgi?horse=017194&HorseName=Socks&Page=1&Sort=0

SGF STIT Blaze, ADCA No. 020128
www.dextercattle.org/pedigreedb/ponyweb.cgi?horse=020128&HorseName=Blaze&Page=1&Sort=0

Because these animals are homozygous for the recessive white spotting gene, it is expressed. When bred with a Dexter that doesn't carry this gene, the offspring from that mating will carry recessive white spotting, but they won't be white spotted.

Dexter breeders have a similar "broken coat color" issue with brindled Dexters. Those Dexters are red with dark tiger-like stripes -- very unique and beautiful to some, but not fitting the "breed description" which calls for a solid black, red, or dun coat color. If they meet the registration requirements (pedigreed sire and dam, sire's genotype on file), they can also be registered.

Patti