The Truth: Every Living Thing Is A Genetic Defect Carrier

Doc said:

This is kinda what knabe has been saying all along. I thought this was a pretty good article.




The Truth: Every Living Thing Is A Genetic Defect Carrier
Aug. 22, 2013By Jared E. Decker, University of Missouri assistant professor and beef genetics specialist
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A new perspective about genetic defects is needed, because all animals are carriers of something.
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Here's the bitter pill. Every living thing – including you – carries a large number of broken genes. In humans, on average, we carry one broken, lethal copy and one normal copy of about 20 genes. In other words, if we had inherited two copies of the broken gene, we wouldn't have survived past birth.

We have about another 80 genes for which one copy is broken, but it’s not lethal. These 80 cause some sort of abnormality or defect if we were to inherit two copies, but do not result in death. The same situation is true for our cattle.

Dorian Garrick, Lush Chair of Animal Breeding & Genetics at Iowa State University, gave a great presentation on this topic at the Beef Improvement Federation meeting in June. Find a summary, proceeding paper, slides, and audio here. Garrick argued that knowing our animal is a carrier is a good thing, because now we are dealing with a known rather than an unknown. He said a new perspective about genetic defects was needed.

Garrick also pointed out that all animals are carriers of something. For example, I recently saw cattle advertised as "100% genetic defect free." The breeder did not realize this, but this statement is patently untrue, and is actually false advertising. The breeder could have stated that the animals are 100% free of known genetic defects, but all animals carry genetic defects.

These scientific facts force us to change the way we view and approach genetic abnormalities and defects. Cattle producers and breed associations cannot rapidly eliminate genetic defects. If they do so, valuable animals with superior genetic merit for production traits will be discarded. Actually, if they eliminated all carriers, there would be no cattle left of the breed!

Rather, genetic defects need to be managed and gradually selected out of the population. By knowing the carrier status of at-risk animals, we can make certain that we never mate two carriers. By doing so, we will increase pregnancy rates and ensure animal welfare.

Certain breed associations allow their membership to manage genetic defects. These associations allow producers to register, sell, and transfer carrier animals and their progeny. Other breed associations will need to permanently alter their policies to deal with our increased awareness of genetic defects. However, we need to discard the stigma attached to the words “genetic” and “defect.” Hopefully these more favorable policies toward defects will increase the rates of reporting abnormal calves.



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Do not dismay, there is a silver lining to all of this. Due to improvements in DNA genotyping and drastic reductions in the cost of DNA sequencing, researchers can now rapidly identify the DNA variant responsible for a genetic abnormality.

In fact, Dave Patterson and Jerry Taylor at the University of Missouri are leading an effort to sequence approximately 150 popular sires from nine beef breeds. This research will identify numerous broken genes. This research will allow us to select against genetic abnormalities long before we observe affected calves.

Knowing that all animals carry genetic abnormalities, there is no reason to throw the baby out with the bath water. We need to accept the fact that all cattle carry genetic abnormalities and adjust our breeding practices. We’ll now have the tools to manage genetic defects while continuing to use animals of superior genetic merit.

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commercialfarmer said:

To have a perfect animal, you should be able to breed brothers to sisters and sons to mothers and fathers to daughters repeatedly with no anomalies in phenotype or function for generation after generation, and to out-crosses. 

Why wait for a test?  Get ahead of the game.  Be a pioneer.  A reproductive pioneer guru.  Though you may not have any breeding stock, I'm sure that many will applaud your efforts.

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Medium Rare said:

commercialfarmer said:

To have a perfect animal, you should be able to breed brothers to sisters and sons to mothers and fathers to daughters repeatedly with no anomalies in phenotype or function for generation after generation, and to out-crosses. 

Why wait for a test?  Get ahead of the game.  Be a pioneer.  A reproductive pioneer guru.  Though you may not have any breeding stock, I'm sure that many will applaud your efforts.

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It wouldn't be pioneering anything as it has been done in multiples species and numerous breeds for decades, if not centuries.

Multiple closed herd farms raise their own bulls and heifers and turn them back into the groups they came from with no consideration of how many half sisters are in the group or if the bull is their father or uncle.  If anything, it's probably becoming slightly more popular than it was a few short years ago.

Some of the greatest bird dog lines in the world are so tight it would scare a lot of people.  Many of the old fox hound lines across the pond were very tight as well.  Unfortunately some of these lines die with their breeders as today's society is not as accepting to "man's best friend" being managed in such a way.

Several commercial sow lines pushed their litter numbers and loin eye size up using multiple generations of tight breeding across large numbers of animals.  Culling in the farrowing house and prior to 7 days of age due to phenotype is not unusual.  Good cheap pork that tastes exactly the same as the last one you bought has come at a cost, most people just don't know, or care, what the cost was.  The commercial poultry industry's methods for producing cheap high quality consistent protein has taken genetic selection and progression to a level the beef industry could never attain.

The beef industry is in direct competition for the same space on the plate as the pork and poultry industry while dealing with obstacles the other industries can work around much faster.  There is no reason to place another "fear of the carrier" hurdle on the track to slow the industry down even more.  Finding it, managing it, and progressing on should be the goal.  Getting scared and slitting the throat of otherwise perfectly good genetics is counter productive to keeping beef on the plate of people who have cheaper options.

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BTDT said:

Commercialfarmer - Actually, I am doing that, especially in my sheep herd. I haven't bought a ram in 15 years, and breed fathers to daughter, mothers to sons, brothers to sisters, etc. Haven't had a wreck yet, and in fact, have improved my REA by 100%, fertility the same, wean an average of 1.8, and DOF at 130 days.

I have found a line of cattle that I really l like, so am slowly doing that. Have a brother/sister offspring that is really special. Next year am expecting a mother, son mating that should be pretty darn good.

I think breeding defective cattle does no one any good. I also realize too many people have too much money involved to just expect them to kill every defect carrier. Again, it all goes back to honesty, and there are just too many unethical, un-honest people in the cattle industry to RELY on honesty. So then you have to rely on research, barn talk, and personal intuition.

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