I'm pretty sure that JFK was sired by Power Plant out of a Total Play cow. Similar breeding to many of the popular bulls of that time - Witch Dr. & Foreplay to name a couple. I have never had a problem with TH or PHA in any of these bloodlines, and I have used them heavily with Heat Seeker and Heat Wave over the years. We had a JFK cow for years and never had a problem calf from her. It took me years to figure out her best mating was surprisingly to Who Made Who! I am usually real paranoid about stacking that much Power Plant in a pedigree, but it worked with her! Her dam was a Sim-Ang. My best guess would be that JFK was free, but you can't be sure what may be in a cows background. Our rule is "If in doubt use free bulls, or test the cow, then you won't have any doubt, you'll know for sure". We test all of our possible carrier bloodline heifers before we offer them for sale. If I end up keeping them, I want to know their status, and my customers deserve to know the status before they decide to purchase. The cost and hassle of testing does make me think long and hard about using carrier bulls, but in the steer business you almost have to use some.