The truck that I was issued was not equipped with the supplies needed to draw blood. At the time I had 12 traps set on two different ranches with the furthest one an hour and an half drive. There was not enough time to draw blood from the pigs. By taking the tongue there is more tissue that can be used to test DNA if it does not work the first time. There is another student that is using the tongues of Pronghorns to test their DNA also. Its just a cheaper, faster,andeasier way to test when more than say hundred animals are to be tested. The student working on the Pig DNA has over 1500 samples from all over south Texas. I hope this answers your question huntnma. And the ranch that I took the big pig from wanted the pigs removed permently.