Tats & Tails, Part 1: Collecting a DNA Hair Sample

August 7th, 2011 by Kim

Washing tails in a bucket of soapy water.

This spring’s Dexter calves are growing beautifully & it’s now time to take care of some registration details.  We had to get the heifers’ ears tattooed for ID as required by the ADCA, and also pull tail hair to send in for some DNA testing.  Yesterday was the big day for the girls, so they were haltered & brought into the barn stall.  We started with the DNA samples, since after tattooing everybody is an inky mess.  If you’ve never done any DNA testing & aren’t sure what’s involved, read on.  It’s not complicated, and can give you some important information about your cows.

A clear water rinse for Ebby’s tail.

What & Why We’re Testing

Trixie is a red heifer out of a red sire & a black dam.  To register a calf as red, either both parents must be red or at least one must be tested & proven to not carry dun.  Since neither of those is the case, Trixie must be tested to prove she is red.  I’m also testing her for dun, to see if she also inherited Ladybell’s dun gene or not.  I’m color testing Ebony as well…just because I like to know what color genes we’ve got to work with.  She is black, and I know she’ll have a red gene from Rousseau, so it’s just a question of whether it’s an E+ or e, and whether or not she got Kiera’s dun gene.  This way I’ll know what possible color calves I’ll be able to get out of these girls when they grow up.

I dry Ebby’s tail under inspection from Marker.

We’re also doing parentage genotyping on both heifers even though this is not yet required for cows.  (The ADCA only requires that all bulls be genotyped at this point.)  It’s coming in the not too distant future, however.  Parentage verification is already a requirement for registration in a lot of breeds of cattle & horses.   This is the ONLY way that you can prove that a calf is indeed purebred, and the only way to make sure our Registry is accurate.  It’s a necessary step in the best interest of the breed.  A step I’ve decided to take awhile on my own initiative.

Our audience for the proceedings: Isaac, Marker & Friday Guy.

The other important thing to test for is the lethal mutations.  Our whole herd at this point is tested, and all are non-carriers of chondrodysplasia and PHA.  I don’t have to test my calves anymore, because they are obligate non-carriers.  All I have to do is mark ‘non-carrier’ on the registration form & make a note that they’re ‘obligate’.  That simple…no worries.  Ladybell is my exception here.  She is not descended from the bull that PHA originated with and therefore can’t be a carrier, so there’s no real reason to test her….especially since she’d rather not be fooled with.  I am testing Trixie, however, just so she’s a proven non-carrier & all of her future calves can be obligate.

I get ready to pull some hair from Trixie’s tail by wrapping it once around my finger.

Getting a Sample

All these DNA tests can be done with a sample of tail hair, which is not hard to obtain…if your animals are used to you handling them.  You’ll want to confine the cow somehow…in a stall, stanchion, chute, etc.  My cows I did in the parlor, giving them feed in the milking stanchion to keep them occupied.  The bulls I did tied in the stall with a feed bucket.  The heifers we just took into the stall, haltered & held on to them.  A little moving around doesn’t matter, and pulling the hair doesn’t really bother them that much anyway.

A quick tug and the hair is mine! Ebby barely noticed.

First, you need to wash that tail switch in hot, soapy water so the hair is not contaminated with anybody else’s DNA (think saliva or shed hair).  I’ve found the easiest way to do this is with a small bucket held behind them, in which I can swish & scrub the tail.  Then dump the (very dirty!) water, rinse the bucket & refill with clear water to swish the soap out of the tail.  Once clean, wash your hands well, dry the switch with a clean towel, and you’re ready to pull hair.

I line up the root ends of each twist of Trixie’s hair on the paper towel Hannah holds for me.

Have a clean, dry paper towel handy…it’s easiest if you have someone else there who can hold it for you, so your sample doesn’t fall on the ground.  Start by getting a small strand of long hair, only about 10-15 hairs.  If you pull too many at once, it DOES hurt!  Give them a single twist around your forefinger about 1″ from the roots, then give a quick tug straight out from the tail.  Place the hairs carefully, root ends together, on your paper towel.  You’ll need to do this about 3-4 times to get the required 30-50 hairs needed for a test, a couple extra pulls if you’re doing multiple tests, like we are.  Then, with roots lined up as evenly as possible, wrap a piece of scotch tape around the bundle of hair a few inches from the root ends and trim off excess hair.  Your sample is ready to put in an envelope with the animal’s information on it, and send to the lab along with the appropriate forms.

(NOTE:  These photos, courtesy of son Joel, are of both heifers mixed together to show the process.  Each heifer was done individually, to avoid cross-contamination by the other’s hair.  If you’re getting samples from more than one cow, you have to go through the whole process one animal at a time and wash your hands & equipment between animals.)

Now that wasn’t so bad, was it?!  Coming next week…the tattoo part!

One Response to “Tats & Tails, Part 1: Collecting a DNA Hair Sample”

  1. Susan Lea Says:

    Thanks for the helpful, informative post. We need to do that!