Purity

[Rob R]

TBH I don't expect the Americans to be the saviour of the breed that grew up on the rocky, boggy west coast of Ireland. They haven't done that with most other breeds I can think of. Whenever a breed is exported it tends to adapt to the climate and topography of the destination, both through actively breeding selection and a degree of natural selection. I see as much of this variety in the UK breed - I know that not every Dexter over here will survive in my environment simply because not all have been bred in my environment.

However, Kirk is talking about type, and you are talking about pedigree. I don't know what the real situation is over there as I do not know either yourself or Kirk so I am going purely on a critical analysis of what you are saying and how that relates to my own experience. From this I highly doubt that people would actively select for animals that result in dead calves over horns. I can see the advantage of not having horns, but I can't see the advantage of a hornless dead calf. Why?

[Kirk- Cascade Herd US]

Absolutely brilliantly put and easy to understand!

Thank you.

Stephanie

Apart from the bit about dun being a dominant phenotype, that's the opposite.

The TYRP1 gene is indeed dominant. TYRP1 stands for Tyrosinase-Related Protein 1. This gene is a type of protein that works as an enzyme to assist in a function. The key purpose of this enzyme is to help make Eumelanin (black) pigment look and stay black. Without at least one good working TYRP1 gene (to provide this enzyme), then black pigment (Eumelanin) fades to brown (Dun).

Any broken copies of this gene wont provide the necessary enzyme to make black pigment look and stay black. The good working copies of TYRP1 are dominant over any broken copies. Dun comes from having both TYRP1 genes broken, and therefore no ability to produce the TYRP1 enzyme.

This underscores how our two-gene (one gene from each parent) system works. In many cases we only need one good working gene from one parent for key functions, because that one good working gene provides the necessary protein or enzyme. This system provides nature with a safety mechanism in case one parent has a broken gene.

The reason this is relevant to the polled and purity discussion, is that it takes millions of years for these good working genes to evolve to produce a complex protein to make black pigment, or to develop horns.... but a DNA copy-error can break these genes instantly. Dun is simply a broken gene. Polled is simply a broken horn regulator gene.

PS... Ask me sometime, about why Polled (a broken gene) is dominant. There is a very interesting likely reason.

[Rob R]

Absolutely brilliantly put and easy to understand!

Thank you.

Stephanie

Apart from the bit about dun being a dominant phenotype, that's the opposite.

The TYRP1 gene is indeed dominant. TYRP1 stands for Tyrosinase-Related Protein 1. This gene is a type of protein that works as an enzyme to assist in a function. The key purpose of this enzyme is to help make Eumelanin (black) pigment look and stay black. Without at least one good working TYRP1 gene (to provide this enzyme), then black pigment (Eumelanin) fades to brown (Dun).

Any broken copies of this gene wont provide the necessary enzyme to make black pigment look and stay black. The good working copies of TYRP1 are dominant over any broken copies. Dun comes from having both TYRP1 genes broken, and therefore no ability to produce the TYRP1 enzyme.

This underscores how our two-gene (one gene from each parent) system works. In many cases we only need one good working gene from one parent for key functions, because that one good working gene provides the necessary protein or enzyme. This system provides nature with a safety mechanism in case one parent has a broken gene.

The reason this is relevant to the polled and purity discussion, is that it takes millions of years for these good working genes to evolve to produce a complex protein to make black pigment, or to develop horns.... but a DNA copy-error can break these genes instantly. Dun is simply a broken gene. Polled is simply a broken horn regulator gene.

PS... Ask me sometime, about why Polled (a broken gene) is dominant. There is a very interesting likely reason.

Ah, yes, sorry, I misread your original reference to the working gene.

[Kirk- Cascade Herd US]

TBH I don't expect the Americans to be the saviour of the breed that grew up on the rocky, boggy west coast of Ireland. They haven't done that with most other breeds I can think of. Whenever a breed is exported it tends to adapt to the climate and topography of the destination, both through actively breeding selection and a degree of natural selection. I see as much of this variety in the UK breed - I know that not every Dexter over here will survive in my environment simply because not all have been bred in my environment.

However, Kirk is talking about type, and you are talking about pedigree. I don't know what the real situation is over there as I do not know either yourself or Kirk so I am going purely on a critical analysis of what you are saying and how that relates to my own experience. From this I highly doubt that people would actively select for animals that result in dead calves over horns. I can see the advantage of not having horns, but I can't see the advantage of a hornless dead calf. Why?

I Highly agree that most true breeds evolve to fit a climate and environment. We selected Irish Dexters (instead of a breed from Spain or India), because our farm in the Northwest coastal area of the US, is very similar to Ireland in temperature and rainfall. Our winters are soggy and cold and our herd has no shelter except some trees, and they thrive.

The interesting thing in America, is that the irrational pedigree purists, don't even have pure pedigrees. They have bigger holes in their pedigrees than the polled breeders do, but the pedigree purists sweep their pedigree holes under a rug.

In the days of facebook and other social media, new Dexter owners report every burp and blink from their animals. Since Saltaire Platinum is somewhere on 90% of all Dexter pedigrees in America, the irrational folks blame him for nearly EVERYTHING negative, even though Saltaire Platinum often only represents 1% - 6% of most of today's pedigrees and the other 93% to 99% of the pedigree are other Dexters, mostly American Traditional Dexters. That's called famous bull syndrome, where folks scan a pedigree for a known name, and attribute too much to that famous bull.

Between my polled "Cascade" Herd in Oregon and the "Legend" polled herd in Texas, we have calved over 300 polled dexters (mostly red) and we can count the total number of problems encountered on one hand. I've bred about 150 polled calves and only had to help one (a breach born to a first time mom many years ago). My herd in Oregon dropped 25 healthy polled calves this last year in terrible weather and no shelter with no help... same thing for the past many years.

One interesting note is that some traditional herds in America have unfortunately tuned their females to only handle 20-30 pound tiny calves... when these breeders put a more robust bull on their weak females, they can have calving problems. They should blame the weak female, but instead, they blame the bull that is tuned to throw robust 45-55 pound calves.

That said, there is NO link between the polled gene and calf size. One could easily create a line of polled dexters that throw 30 pound calves, but the danger in doing that, is that you might accidentally be selecting females that have trouble birthing 50 pound calves.

[Rob R]

The US is certainly home to a variety of climates, and in that I'd expect it to be home to a variety of types of animals. You can select for ease of calving, and you can select for polledness, but I've never heard of anyone linking the two traits in the way Judy has. I shall await her explanation on that one though.

[PorcPrunus NL]

If American Dexters are losing the characteristics of the breed description, ACDA should help people to select better. DCS-judges are very knowledgeable and most of them would be delighted to help.
Try to breed foreward, not miscall Dexters for what went wrong in the past.