BioTracking is the company I use and the cow must be atleast 30 days bred before they can test positive for preg.
I just got my results back 2 weeks ago, they only can give you a PREG or OPEN. If you know when they were bred then you should have a good idea anyway of the length, this is a great tool for someone doing AI.
Here is a list of items you will need:
Air-Tite Products Co., Inc. has supplied syringes, hypodermic needles and related supplies to veterinary, human health and industrial professionals since 1926.
PURCHASE: Part Numbers: 1) NBT, 3 to 5 Needle Holder, 2) BD366668, 100, Red topped tubes, 3) NBC 181, 100 Needles, 18 gauge by 1 inch
and the link to their site, the supplies with shipping will run around $40.00 and it is enough for 100 samples if you don't waste any items.
http://www.air-tite.com/
the red top tubes are good for about 2 years, that was what they told me.
I mailed my sample via express mail (2-3 days and the results were back to me the day after they received the samples. I got a fax and email results and they called me a few days later and asked what I thought about their service.
so far so good