th and pha

[vet tech]

I have heard some people talking about the advantages of th and pha bulls. They say stuff  like "looks like she needs to be bred to a th bull" Do they have any physical advantages ???
thanks

 

[showsteerdlux]

Th calves typically have more hair. However when carriers are bred to carriers there is a 25% chance of the calf being born dead and a very hard birth for the mother.
PHA has been related to growth but again carriers bred to carriers = a big wreck.
IMVHO Th is the lesser of 2 evils when managed correctly.

 

[BIGTEX]

TH and PHA are like using steroids in baseball. Use 'em or get beat by people who are.  I think T stands for THICK and H stands for HAIR.

 

[Turkey Creek Ranch]

I did a report on this stuff, and it is very interesting, but, IMHO, it isnt worth the risk. I can see maybe breeding an Angus cow (no TH/PHA in genetics) to a Clubby bull for steers, but i wouldnt breed any other breeds to the clubby bulls that might be carrying the defects. That's why we just stay with our good ole Angus.  <cowboy>

 

[knabe]

what would be great is if you could get sexed semen that was sorted for TH so you would almost always know you would get a carrier and wouldn't have to fool with female carriers.  there probably is not a benefit of having female TH carriers unless you wanted to mate to clean bulls and get a carrier calf, but then the odds would only be 25%.  i still think the price of clones will come down far enough that if top dollar calves are "worth" 30,000, a clone is relatively cheap, especially if the yield on the number of clones gets to be a lot higher.  still, in the long run, there will be a new freak, and hopefully it won't be associated with a defect.

with in the field testing available, it may be someday be relatively cheap to say just test the champ and reserve for the defect and sort them for a TH+ class, then have a grand champ class.  that way you could have a grand champ "free" class and push a little harder to generate animals without defects.

 

[Dusty]

  there probably is not a benefit of having female TH carriers unless you wanted to mate to clean bulls and get a carrier calf, but then the odds would only be 25%. 

I've got to call you on that one, the odds would be:

50%-carrier
505-Clean

Cow=Tt-carrier
Bull=TT-clean

                                T        T
                   
                      T      TT        TT

                      t      tT        tT


         

 

[knabe]

goes to show the square is the best method when you are thinking about two ratio's at once.

 

[DLD]

vet tech, here's how I understand the relationship of TH and PHA to phenotype;

The TH defect is expressed as a deletion in the gene sequence that forms the hind legs and appears to be associated with a straighter hind leg and possibly heavier bone structure. There's alot of talk about it being linked to (more) hair, but that appears to be an indirect relationship, possibly due to the original source of the defect also possessing extra hair, or possibly because the "show steer hind leg" has been selected for along with extra hair.

PHA on the other hand isn't associated with any particular gene sequence, but rather a change in the chemistry of the DNA, so it doesn't appear to have any direct relationship with any phenotypical trait. Obviously, many of the known carriers share "that showring look", but that hasn't been proven to be anything but coincidental.

 

[vet tech]

vet tech, here's how I understand the relationship of TH and PHA to phenotype;

The TH defect is expressed as a deletion in the gene sequence that forms the hind legs and appears to be associated with a straighter hind leg and possibly heavier bone structure. There's alot of talk about it being linked to (more) hair, but that appears to be an indirect relationship, possibly due to the original source of the defect also possessing extra hair, or possibly because the "show steer hind leg" has been selected for along with extra hair.

PHA on the other hand isn't associated with any particular gene sequence, but rather a change in the chemistry of the DNA, so it doesn't appear to have any direct relationship with any phenotypical trait. Obviously, many of the known carriers share "that showring look", but that hasn't been proven to be anything but coincidental.

Ok thanks for all your help everyone

 

[knabe]

PHA on the other hand isn't associated with any particular gene sequence, but rather a change in the chemistry of the DNA, so it doesn't appear to have any direct relationship with any phenotypical trait. Obviously, many of the known carriers share "that showring look", but that hasn't been proven to be anything but coincidental.

a change in DNA sequence will change chemistry if the protein is changed, which is most common at the 3rd position, and therefore since many proteins can have a different base at the third postion without a change in protein.  even changes in the dna without a change in the protein have been known to cause problems, and this is actually a recently discovered phenomenum.  i posted a link on the planet before about this.

look at the RNA chart here.
http://en.wikipedia.org/wiki/Codon


the phenotype most often cited with PHA is upper spring of rib in females.

 

[DLD]

As always Knabe, I'll defer to your genetic knowledge - I knew my explanation was over simplified. But are you saying that there is an actual proven direct relationship between PHA and upper spring of rib in females? And is it believed to always exist, or just sometimes? I believe there are many phenotypical similarities in the known carrier lines (Draft Pick, Stinger and Payback) but I've always understood that they were coincidental due to the fact that these gained their popularity primarily in the showring.

Not arguing your point at all, just trying to understand it better...

 

[knabe]

As always Knabe, I'll defer to your genetic knowledge - I knew my explanation was over simplified. But are you saying that there is an actual proven direct relationship between PHA and upper spring of rib in females? And is it believed to always exist, or just sometimes? I believe there are many phenotypical similarities in the known carrier lines (Draft Pick, Stinger and Payback) but I've always understood that they were coincidental due to the fact that these gained their popularity primarily in the showring.

Not arguing your point at all, just trying to understand it better...

no need to defer, notice my lame mistake above.

you are right that the trait may not be the spring of rib and that it is just chance.  it's just that a lot of people have commented about the spring of rib and carriers since this appears to be a trait in short supply in the maine breed.  what i hope is happening, is that there is another region of interest in the PHA gene other than the defect and that this is linked and that carriers had this change more often than non carriers, so the spring of rib may be linked within the same gene and not due to PHA itself.  i'm also of the belief that PHA in a carrier state, that this is related to birth weight as many carriers had low birth weights, including some direct sons of paramount, some carrier direct sons of draft pick etc.  if the spring of rib is IN the PHA gene and non-carriers have it, and it's not recessive, this would be interesting, as you would need both copies.  if it's dominant, and the female had none, you would have a 50% chance of the offspring having it if the bull was hetero.  this could be a case where "prepotency" would be apparent.  if a bull was homo for a dominant gene, he would appear prepotent, if he was hetero, not so much.  if gene was recessive, you would need both copies and depending upon population of gene in herd, it could appear a bull was prepotent, even though he isn't.  this is why i think line breeding is so important, to figure out these things.  it will probably be a case that a newfound interest in line breeding will commence and we can find these things out.  otherwise, one will have to wait for genetic tests on positive traits, usually additive from companies, as these are easier to market, ie bovigen, vs. recessive genes for positive traits versus defects.