I have gotten even less positive about relying on the vet's "preg check".... bought an 8 month bred and she calved the next day.
But our own vet has been off quite a bit lately with shorter bred cows.... calling several open (that were 2-3 months); we put them back with a bull because several were young cows with big strapping calves.... and have had to pull the bigger calves off because 2 have just dropped a new calf.... Got another one this evening that dropped a brand new one so her older calf has to come off... it is not a real big calf so I don't know if she is not milking the way that she should.... but I am hoping that the new calves get along since I was not expecting new ones. We were getting ready to bring them all into the barn and preg checked and the calves sold.... so the 2 have had the older calves pulled and sold... now got to do this other one. I think there are 3 more so, the cows will get brought to the barn and checked now, the calves will get pulled to sell.
We try to have a more defined calving season, but with my son breaking his hip nov 2019 and my ankle replacement in feb 2020.... bulls did not get pulled and not all the cows did as good through the winter feeding so some just did not cycle.... friends helped out alot but some things just slid by.... it could be worse.
Hope to have a better defined calving this fall and get back on track. But the good thing is we did not sell some of the younger "open cows" and even though they are a little out of synch from their original calving group, they are calving now with the spring calving bunch.
A vet that used to do alot of the dairies told me once that when you get over 5-6 months, the calf is so far down over the pelvic floor, and the calf grows at different stages in different cows, that it is very hard to tell when they are over 5+ months.
I can tell if they are bred after 5 months so on the ones that are supposed to be further along, I will check. I am trying to get son to let me get the one vet I like to come and do the ultra sound.... more reliable AND easier on the cow than just palpating.... won't disrupt a short pregnancy as much either....