Bull with translocation gene, semen testing questions

[djinwa]

Was looking at semen from a bull. Breeder had stopped selling it because they said it was tested for export, and found to have a translocation gene.

If I understand correctly from my reading, all the genes are normal, but just paired up slightly wrong in the chromosome, so 10 to 20% of embryos are aborted right away and the cow can be bred the next cyle or two. If that embryo is okay, they have a normal calf. So if have a bull running with herd, might not notice an extra breeding here or there, but if doing AI, would notice more.

The breeder says they haven't seen any decreased fertility in the bull's female offspring.

Looking for some perspective on this.
Has anyone dealt with this problem or is familiar with it? Just wondering how common it is, and if people worry about it. Also wondering which semen gets tested for it. Breeder said it is rarely tested for, so makes me wonder about other semen I have.

Here are a few links I came up with:

http://homepage.usask.ca/~schmutz/chromosome.html

http://www.sciencedirect.com/science/ar ... 1X91904116

http://pubs.aic.ca/doi/pdf/10.4141/cjas89-102

 

[Lucky_P]

Vague memories of a 14/20 translocation in Simmental cattle, back in the early 80s, traced back to one particular sire, whose name I no longer recall.
Don't think I ever used him, but seems like there were some issues with below average fertility in the offspring - not a high percentage, but enough failures that folks got to looking for a cause.

 

[Kathie in Thorp]

Is this something that would normally be tested for in conjunction w/ a BSE exam or otherwise?

 

[inyati13]

djinwa, the mechanisms which can alter the status quo and cause genetic outcomes that no one expects. Everyone hears about "mutations" but they don't often hear about Translocations, crossing over, inversions, duplications, buckling, etc. All which cause unpredictable genptypes and phenotypes just when you think you have everything nailed down. Sometimes parts of a chromosome become detached and reunited with non-homologous chromosomes. That is bad news for that zygote as it is to use the term "screwed up". Being screwed up, nature finds a way to abort it. If it does not abort and goes term.
A translocation gene is bad news as you just cannot have confidence that the geneotype is going to be as expected. If this bull was in your pasture, even when he gets a cow pregnant, she may later a abort.

 

[Kathie in Thorp]

I think that's what Dale said, inyati13. BUT, is it commonly tested for?

 

[inyati13]

I think that's what Dale said, inyati13. BUT, is it commonly tested for?

I would think so if you were going to market a bull to sell his semen. But I am only guessing. But here is what I wonder if people fully appreciate if they are not genetics buffs. These genetic maladies can happen and you really have no clues that things are fouled up so how would you know to test for them? I do not work around this but I would think they screen for the most commonly occurring maladies and only learn later if things are not going well. Kind of like Fire Sweep told me. They were having poor success with AI and later found out the thawing cup had a short but they lost a whole breeding season until theu founf it.

Such is life.

 

[Kathie in Thorp]

I think that's what Dale said, inyati13. BUT, is it commonly tested for?

I would think so if you were going to market a bull to sell his semen. But I am only guessing. But here is what I wonder if people fully appreciate if they are not genetics buffs. These genetic maladies can happen and you really have no clues that things are fouled up so how would you know to test for them? I do not work around this but I would think they screen for the most commonly occurring maladies and only learn later if things are not going well. Kind of like Fire Sweep told me. They were having poor success with AI and later found out the thawing cup had a short but they lost a whole breeding season until theu founf it.

Such is life.

Does anyone KNOW -- is this a test usually run on bulls whose semen is sold? Not asking for speculation; asking for experience.

 

[djinwa]

Is this something that would normally be tested for in conjunction w/ a BSE exam or otherwise?

Never part of a BSE that I was involved with.

But you would think if you are scattering genetics around with semen collection and AI, it would be worth testing for. Apparently for export, countries require testing.

Just wondering if it is not considered a serious enough problem to warrant testing, or if it is just too rare.

I might contact a semen company and see what they have to say.

DJ in Washington

 

[Willow Springs]

It isn't a test that is normally done unless the Breed Association in the importing country requires it. Some of the French breed Associations in Canada require any imported animals, semen or embryos to be tested or the donors tested and carriers are kept out of the herdbook. The French herdbooks have similar rules in terms of AI bulls even for domestic sales as do many Canadian Associations for French breeds. Outside of Canada/France there is no testing that I know of and very little knowledge of the issue.

In terms of fertility issues; we had a sire that turned out to be a carrier that really sired poor fertility in his daughters. At the time we didn't know anyhting about tranlocation, just thought his daughters didn't have great fertility. I am sure it was a combination of the translocation and other fertility factors. We also had a female that produced every year on a decent calving interval until she was 17. Didn't find out she was a carrier until she was tested prior to embryo production. The reading i have done only indicates a 5% death loss of embryos, so hardly something to get over excited about. Wouldn't want a herdsire passing it to all his daughetrs though.

 

[djinwa]

Thank you, Willow, that's what I was looking for.

So as I kick this around in my head, it would be hard to use a bull that you know would pass the problem to his daughters (and sons).

On the other hand, you only know he has it because he was tested because he was good enough to be exported.

So you could go with a bull of lesser quality, who might also have it, but he was just not good enough to be tested.

Or should you figure it is so rare, that the untested bulls very likely don't have it? Doesn't seem fair to the ones that did get tested.

I'm just a small timer so this is new to me - maybe there are a lot of things we just don't want to know about.

 

[Willow Springs]

If you use the carrier bull you will have approximately 50% carriers in his offspring. If you cull for fertility issues on the daughters you will weed out most of the ones with the translocation over a period of time. Depends how much you think these females are worth to you, but in a commercial herd the cows that calve in the first cycle for ten years are the most profitable. Culling young cows is not. If you are buying from breeders with sound culling practices in regards to fertility most of the carriers within a population should be long gone, so you should be safe buying form these types of breeders. However as I said we did see varying results in terms of how much individuals were affected.

 

[Red Bull Breeder]

Semen collected for export get a lot more testing than semen collected for use in the US. If are exporting semen to different countries each country may have different things to be tested for.

 

[inyati13]

Semen collected for export get a lot more testing than semen collected for use in the US. If are exporting semen to different countries each country may have different things to be tested for.

Red Bull Breeder, how much testing is required if someone wants to import semen from say France which seems to be very strict on imports?

 

[djinwa]

If you use the carrier bull you will have approximately 50% carriers in his offspring. If you cull for fertility issues on the daughters you will weed out most of the ones with the translocation over a period of time. Depends how much you think these females are worth to you, but in a commercial herd the cows that calve in the first cycle for ten years are the most profitable. Culling young cows is not. If you are buying from breeders with sound culling practices in regards to fertility most of the carriers within a population should be long gone, so you should be safe buying form these types of breeders. However as I said we did see varying results in terms of how much individuals were affected.

Sure seems like it would be cheaper to test more bulls in the first place instead of culling later - especially the high use, AI bulls.

Again, I suppose if this is a very rare thing, might not be worth testing, but if rarely test, maybe its more common than we think.

As far as culling, the one article mentions with certain management practices, the lower fertility might not be noticed. And the breeder said they've seen no decreased fertility, so haven't culled anything. We know there has to be delayed calving occasionally, but whether it is significant enough to be noticed is the problem. If a cow is a cycle or two later than would be otherwise, breeder might either not notice, or attribute it to other factors like hot weather or something.

I don't plan to use the bull, but now I'm wondering since few bulls are tested, what are the odds of the untested ones having the problem. I might call some genetics guys and see what the latest is.

The article from 1989 said this about the incidence:

"The translocation has primarily been found
in the European continental breeds of beef
cattle and rarely in the British breeds. The
incidence of the translocation is not well
documented in Canada but McWhir et al.
(1987) found 2.5% of the beef cattle they
studied in Alberta to carry the 1;29 translocation
and Bongso and Basrur (1916) reported
it in Guernsey cattle in Ontario. We have
found several beef bulls with the translocation
in Saskatchewan as well (unpub. data)."

DJ in WAshington

 

[djinwa]

Let me beat this to death.

Was just re-reading the 1989 paper I linked above. I see now what Willow was saying that with proper culling you can decrease the incidence, though never get rid of it, unless you test. And it is more obvious which to cull if you keep exposure time to bull short, or use AI.

Also interesting that it says several AI centers are doing or considering routine testing (karyotyping) of all semen donors. Slow progress there 24 years later.

The impact of modern practices of relatively
short bull exposure and/or the use of
artificial insemination may have resulted in
much more obvious evidence of reduced
fertility. Such practices would result in several
nonpregnant cows in the fall which would
presumably be culled. This in turn may have
lowered, although not eliminated, the translocation,
as appears to be the case in Clay
Center (Maurer and Vogt 1988), but produced
many fewer calves/exposed cow. Gustavsson
(191 l) reported that significantly more
daughters of translocation carrying dairy bulls
than of normal bulls were culled, presumably
due to lower fertility.

One management strategy which could be
recommended to producers wishing to eliminate
this l;29 translocation from a herd,
several generations after its introduction, is
to breed each translocation cow until a
replacement heifer with a normal karyotype
is produced. However, the data collected from
this herd corroborate the theoretical prediction
of a 25% chance of obtaining a heifer
with a normal karyotype from a translocation
carrier cow. Therefore. economics could not
generally warrant such a replacement strategy
unless the cow was very exceptional.

At the present time, there is little if any
legislation in North America regarding this
translocation. Several artificial insemination
centers have instituted, or are considering,
routine karyotyping of all semen donors.

Although overall incidence of such translocations
may be low in most beef breeds,
frequent use of particular affected bulls could
cause widespread dissemination. If the translocation
is carried by a main herd sire, the
level of this translocation can quickly reach
the expected proportion of 50% of the herd
and remain there causing low but insidious
levels of reproductive loss. Levels of loss are
clearly, as in many conditions, also affected
by management practices and therefore vary
among individual herds.

 

[inyati13]

djinwa, what stikes me is that the information you provided and the discussion in this thread are related to a specifically identified translocation (1;29 Robersonian translocation). To expand the scope of the discussion, all bulls have the potential to carry known and unknown translocations. Which means to you, that there is not zero risk even if you select a different bull. Take it one further step, if it is a new translocation (and the potential for new translocations are infinite as they are defined by where on the chromosome the break occurs) then no one would even have a test for it unless they had a comprehensive genetic map of the bull/genetic fingerprint. I looked at the chapter in my genetics book,"Principles of Genetics" by Eldon J. Gardner, 1968. Outdated, but the principles of translocation seem to be the same. But in the decision you are making, you could also factor in that all semen has the potential, albeit small especially if the bull has a track record and it has not showed up, to exist. Translocations according to my understanding from glancing through my text, can even occur during the process of spermatogenesis. Thus, a bull that is clean today could be collected tomorrow and send out semen that harbors the genetic defect. I just add this disclaimer, I only briefly reviewed the chapter. You are correct to consult one of the semen companies. If you do, please come back to this thread and provide your findings. I would like to know about the incidence of bad semen in an otherwise non-defective bull. Thank you. I have appreciation for a topic like this.

 

[Kathie in Thorp]

I'll make this question short -- Do the major semen suppliers in the USA require a check for the translocation gene -- for any translocation gene affecting fertility, no matter what prefix is attached to the name of it?

 

[inyati13]

I'll make this question short -- Do the major semen suppliers in the USA require a check for the translocation gene -- for any translocation gene affecting fertility, no matter what prefix is attached to the name of it?

Kathie: THIS IS NOT AN ANSWER TO YOUR QUESTION. But either you or I do not understand the tranlocation process or maybe both of us don't. Your question seems to imply a misunderstanding. Maybe I am out of line pointing that out. Your question implies that there is a translocator gene that causes translocation. I have researched using google and I cannot find a single reference that implies a so called "translocator gene". I consulted my genetics text. I see those words in the title but I cannot find them any where else. NOT even in the references provided by djinwa. However, I could not open the third reference down. The term translocated genes is a different meaning. Yes the genes are "translocated". Translocations occur in the process where egg and sperm are produced, (Robertsonian type translocation). During cell division process (meiosis) that produces in this case sperm, the chromosome pairs line up and separate. When they separate, the limbs of the chromosomes can become broken and get mixed with other chromosomes (translocated). What happens is parts of a chromosome become detached and reunited with non-homologous chromosomes. The resulting zygote that is created by that defective chromosome either goes to term, is born and then becomes a carrier of that defect (translocated series of genes) or it dies and no one ever knows about it occurence. There is no reference to a "translocation gene" that turns this process on and off as one would see in other genetic anomolies. If you look at the first article djinwa put up, it is about as good as I found.

As a result, what they are testing is for a set of chromosomes the gene sequence would not be "normal" because it has been translocated. The abnormality djinwa is referring to is a known tranlocation (1;29) which means pieces have been exchanged between the Number 1 and number 29 chromosome (Robertsonian Translocation).

BTW, all translocations are almost sure (I say almost to allow for an exception) to affect fertility because a translocation is not normal and has a statictical probability based on that translocation of being abort. There are literial an exponential number of translocations. The semen can be tested for the known translocations but each translocation would require its own test.

I know I am a smart azz and that is OK with me but in this case I am sincerely trying although I may be doing a very poor job of pointing out what looks like a misunderstanding in your question. Anyone who can get on here and explain if what I say is correct would absolutely delight me as I also would like to know.

Is your question, "do semen companies check a bull to determine if he carries a translocation? All translocations will affect fertility to some determined percentage. That I can answer. Please don't get upset. I took a little of your time and it is none of my business but my intentions although maybe misplaced are good. Thanks.

 

[pdfangus]

inyati13.....

I thought you did a good job in trying to answer the question....

let me try to oversimplify....a translocation is not a genetic malfunction as much as it is a physical malfunction of genetic material...

if genes were an automobile
tires are part of the dna
a translocation is like a tire falling off and going thru the window and landing in the back seat....
hard to predict but it still caused a wreck....hopefully no fatalities....

 

[inyati13]

inyati13.....

I thought you did a good job in trying to answer the question....

let me try to oversimplify....a translocation is not a genetic malfunction as much as it is a physical malfunction of genetic material...

if genes were an automobile
tires are part of the dna
a translocation is like a tire falling off and going thru the window and landing in the back seat....
hard to predict but it still caused a wreck....hopefully no fatalities....

Thank you. I just got back from the YMCA and I was on the machine thinking I did not do a good job. I just start typing sometimes and I may hurt peoples feelings. It is not my intent as much as it is my brain running as it does.

I like the way you said that. The point is that it is not like there is ONE TRANSLOCATION out there and semen companies can do that one test and they are done. MY GUESS IS THAT THEY HAVE A LIST OF THE COMMONLY OCCURRING TRANSLOCATIONS IN THE BREED THEY ARE RUNNING SEMEN FOR AND THEY RUN THOSE TESTS. THAT WOULD BE FOR EXPORT FOR SURE. ON SEMEN USED IN THE US AND CANADA I WOULD HOPE THEY HAVE A SHORT LIST FOR THOSE. BUT I DID NOT WANT TO PROVIDE A GUESS IN RESPONSE TO KATHIE'S QUESTION.