It's our primary way of checking pregnancies. It's less invasive, can be done on our schedule, not the vets, and is cheap. It's great for us as we have cows in several pens, so we can move them around with less stress because we don't have a vet waiting. Plus we can do it ourselves. It's fairly easy to draw blood from the tail (though some cows are easier than others to bleed). we can check pregnancies at 30 days, which is very helpful with recips. BioTracking charges $2.25 per sample and has results back in 3 days. We like it...Nancy
I don't know what lab some folks in our area used, but they got about 10-15% false readings (mainly false positives).
Ultrasounding can be done accurately at 30 days and cost around $3. But of course, that depends on if you live in an area where that is available!
I believe BioTracking has a 98-99% accuracy. If I remember correctly it was a professor or Dr. or something that found the PSPB protein and then made the BioTracking Company. I guess the others are generic spin off's and I'd expect them to have lower accuracy.