Another thing to take into consideration is how hard she is working and if she has been disturbed or not. A cow/heifer that has been laid back pushing hard and not making progress should send up red flags, especially if she can't stand up and/or is obviously tired. A cow/heifer that has been walking and up and down a lot but hasn't really given any good pushes may just need more positioning time and more time to dilate. And a cow/heifer that started calving and has been disturbed, either by other cows or people may take awhile to get back to business - especially if she is a little wild. BUT if it looks like they are giving up...hard pushes with no progress and then they get up and go start eating, lots of bellering, rolling totally on their side and you either haven't seen feet or feet are there but no nose, and they aren't moving in or out... I'd "dive" in!! We check for progress every 15 minutes unless we think there might be a problem, then we watch constantly. Time can be in a warp when you are watching them calve so make sure to check your watch - 2 minutes can seem like 10.
