Stories of life on our farm in Northwest Georgia where every day is an adventure in this beautiful spot that God has entrusted to our stewardship.

Tuesday, December 2, 2014

Parentage Verification: Why Is It Important?

Parentage Verification is something that has been my goal to achieve for our entire herd ever since I understood what it meant.  I posted previously about our whole herd now being "Sire and Dam Qualified."  Here I'm all excited, while you may be asking, "So what?  What's the big deal?"

We have two black polled cows, Ebony and Siobhan.  I can easily tell them apart, but the rest of my family can't.  This year we had two calves born on our farm.  Ebony, above, had a black polled heifer we called Tiggy.

Six weeks later Siobhan had a red polled bull calf named Wellie.  My previous post ended with the account of how Wellie was parentage verified at the UCDavis VGL.

"So," you might say, "that seems like a whole lot of trouble and expense just to prove what you already knew--that Wellie is Siobhan's calf by Cash!"  It's true that there's no way I could confuse Tiggy and Wellie, so why did I bother with all the PV stuff?

It all started this past summer when someone made this statement on the Dexter forum I belong to:

"The very term "Sire Qualified" describes a useless status. Comparing the genotypes of an alleged offsprin (sic) with an alleged sire can not show any meaningful level of assurance that the two are related. The only parentage verification worth anything is "Sire and Dam Qualified."  (I will not identify the poster by name because they have since deleted their post and I cannot provide a link to it.)
I was confused, so I called VGL to get an explanation.  The person I talked to was astounded that "Sire Qualified" had been called useless.  However, as she further explained Parentage Verification, I understood that the poster was trying to say this:

"Finally, it is important to remember that while parentage exclusions are 100% accurate parentage qualifications are not. The accuracy of most animal parentage tests is greater than 99% when both parents are included in the analysis and drops to around 95% when only one parent is included in the analysis. However, this accuracy will decrease when the potential parents are part of a large group of closely related animals." 

The very helpful lady at the lab gave me an example using actual genetic markers from a case they were working on.  (She did not tell me the name or even the breed of the animal.)  I can't remember the markers and numbers she used, but here's a simplified version of what she told me using a fictional "Marker A":

If the lab compares the calf's and sire's genotypes:
Calf: Marker A 100/200
Sire: Marker A 100/300
This bull qualifies as this calf's sire.

If the lab compares the calf's and dam's genotypes:
Calf: Marker A 100/200
Dam: Marker A 100/400
This cow qualifies as this calf's dam.

However, if the lab compares all three animals at the same time:
Calf: Marker A 100/200
Sire: Marker A 100/300
Dam: Marker A 100/400
One of the parents does not qualify.

Remember what I wrote in my previous post?
"You'll remember that an individual (in this case, a cow) gets half of its genetic material from each parent, so this animal got the 217 from one parent and the 221 from the other. Hold that thought; it's going to be important."
Well, now it's important.  This calf cannot have gotten the "100" from both parents; the "200" had to come from one of them, but neither of the parents has a 200 on that marker . . .

Somebody's got a problem!

The example above is very simplified, but this scenario has actually happened, even with Dexters.  People have bought cattle . . . and when they tried to PV those animals, they learned that one or even both of the parents on the pedigree did not qualify as the sire and/or dam.  Here is a recent discussion about just such an issue on the Dexter forum.

If you read the entire discussion, you will see that experienced breeders shared some excellent advice:  The only way to be sure that something like that does not happen to you is to buy only "Sire and Dam Qualified" animals for breeding stock.  

We have owned Dexters since December 2009.  Our first calf, Siobhan, was born in 2010, over four years ago.  She was PV'd--because we had her genotyped at TAMU and they did it automatically.  When we bought Ebony, we got her genotyped at VGL so her previous owner could PV her calf because the sire was there.  They had bred Ebony and had her sire's genotype at VGL, so it was easy enough for me to get her PV'd.  I could see that it was the highest "G" level accorded on the pedigree, but I still didn't understand why it was important!

Two things helped me realize how vitally important PV is:
1)  My conversation with the lady at VGL, and
2)  My acquaintance with the serious problems a few fellow breeders were facing as they discovered that their prized Dexters didn't even carry the bloodlines for which they had purchased them.

Accidents happen.  An AI'd cows slips her calf and gets field bred by a different bull . . . A bull jumps into a pasture, breeds a cow, and jumps back out again without anyone knowing . . . A neighbor's bull does the same thing . . . Two cows switch calves with each other . . . A bull calf gets left with the herd too long and breeds an open cow . . . The steer running with the open cows wasn't completely castrated . . .  These are actual scenarios that have happened, and they cause nightmares for the new owners and headaches for the breeders who have to sort out the real parents.

This is why we wanted that highest "Sire and Dam Qualify" designation.  Now that our herd sire and cows are all fully PV'd, one simple test for every calf born on our place will guarantee its lineage.

We believe that Parentage Verification is an indispensable part of good breeding--the crown of all our efforts and the final stamp of certainty for our clients.  If we've gone to the trouble to breed an animal, we ought to guarantee that it's everything we say it is.  With PV, we rest assured that the animals we sell are exactly who we say they are!

Feel free to use the "Contact Susan" form under the ADCA logo on the right of this blog if you have any questions.  If you prefer to talk on the phone, send me your phone number and I'll be glad to call you.  Stay tuned for an upcoming Q&A on Parentage Verification.

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