TH question

I have just started keeping back some heifers out of some of these show lines and I would like to know more about how TH is passed on.  I am pretty sure that my commercial mainexangus cows are THF, but don't know that for a fact.  If I used some THC bulls and kept the calves as replacements, what are the chances that they are THC?  Is it terrible to keep THC females as replacements?  Any opinions, experiences or thoughts would be appreciated.

If you breed a THF cow to a THC bull the chances are 50/50 that they will have TH, in theroy half the calves would be free and half would be carriers. The only problems you will have is when you breed two carriers together, then you have a 100 percent chance of having a TH calf.

SHAGGY said:

The only problems you will have is when you breed two carriers together, then you have a 100 percent chance of having a TH calf.

Click to expand...

While I don't think it is a good idea to breed to carriers together, this isn't true.  If you do breed two THC together you have 25% chance clean, 50% carrier, and 25% TH calf. 

And to think the "experts" think this is "old news and shouldn't be discussed anymore..." 

If I were you shufly, I would test your entire herd. That way you would know for sure, and then breed accordingly. Yes, it may cost a bit (depending on how many cows you have), but it will save you money down the road.
I would not keep THC as replacements, but it is your herd, do as you see fit and what allows you to sleep at night. As long as you test all possible carrier genetics and sell them accordingly and honestly, I have no problem with it.
It is those that sell known carrier genetics without testing or full disclosure that is a problem in my opinion.


Shaggy - Actually depending on symantics (which has been an issue on this board)  "having TH" can mean two things, 1. Be dead due to CC, or 2. Be a carrier but alive. Crazy words anyway.

It does not matter if you breed carrier to carrier OR carrier to free - you have a 50% chance (risk) that the offspring will be a carrier

The risk is the same for every mating - like tossing a coin - you can't say I had a carrier now the next one will be free - doesn't work that way

The difference in risk is when you breed a carrier to a free you have a 50% chance (risk) of having a free calf, but when you breed a carrier to a carrier you have a 25% risk of having a free calf and a 25% chance of having a dead or affected calf

Those risks are the same for all of the lethal and nonlethal recessive defects - TH, PHA, AM, NH, OS, MA, IE and FCS

   

As long as you test all possible carrier genetics and sell them accordingly and honestly, I have no problem with it.



[/quote]

someone is signing a slighty different tune, Do Da Do Da

How do you sign a song? Sign language?

aj said:

How do you sign a song? Sign language?

Click to expand...

Maybe she's signing to a hypocrate!!!  ;D

I have never changed my tune. Still will not breed to a carrier that I will have born in my herd. Will not have a carrier in my herd.  Will not buy anything that is not either tested or guaranteed free. If shufly wants to have carriers, or has them in the herd already, and chooses to use them, then I highly recommend that they are honest about it and test all possible carriers and sell/market honestly.  Never have I waivered from that stance.

Shufly, I have re-read your question, and just want to clarify that TH, as well as many other lethal defects, are passed through DNA (Genetics). 

Thanks to everyone for you imput.  If I sell any females  I would definitely have them tested and be honest on their TH status.  I haven't sold any females to this point, just steers.  I personally think that even if they are carriers that their are plenty of good THF bulls to breed them to.  I would love to hear more about the Pfizer hair test for TH and PHA that was mentioned in another thread if anyone has done this rather than the blood test?