Posted 11/25/2021 07:21 (#9340025 - in reply to #9337113) Subject: RE: Preg checks, and milk tests?
I've been using the milk tests since 2013.
If the test says OPEN, then they are not pregnant. 100% reliable if OPEN is the result. Find a way to get the cow cycling or get rid of her.
If the test says PREG, then 95% of them are pregnant. The other 5% were pregnant but slipped the embryo in the past 3 weeks. You should retest in 30 days to confirm OR watch for heats.
I love my vet. But unfortunately, his preg checks were not much more accurate than the milk test. 5% of his PREG cows came open in 30 days (and sometimes his open cows came back pregnant the next check). When I asked him to buy an ultrasound, he bought one and that did improve his results slightly.
The milk test is so easy and fairly inexpensive (blood test is cheaper, vet is about the same). My milk tester pulls an extra sample on test day and the lab does the rest. I get results in 3 days. No extra labor involved in locking up the cows to pull blood or wait on the vet to show up.
To your question about the ratio result: The higher the number, the better chance of her being pregnant. I think they need to be above .25 to be considered pregnant. Early in the pregnancy, the number is lower. So if you test at 30 days, it may come back at .25 and then test at 60 days it should be higher (usually over 1.0, but not always).
If she loses the calf, then the number goes down until the antigen clears her body (usually 3 weeks). So if you test at 40 days and get a .5 result, then test at 70 days and get a .25 result, she probably lost the calf in that 30 day time frame.
I don't think the high components have any effect on the test.