My friend has a Double Stuff cow. This cow was tested free of Pha and positive for Th. She is therefore a Th carrier cow. She was mated to Hannibal, and produced a heifer. He just got the tests back on the Hannibal heifer, and she is negative Th and positive Pha. I am assuming that Hannibal has been tested free of both. If he is double clean, how is this possible? Does this mean that the test done on the Double Stuff cow were incorrect? I have always assumed that clean mated to clean could only resullt in a clean calf. Any thoughts out there?