Every day at the farm is different and this week specifically was one in which a couple of the cows were getting checked for pregnancy. The vet that works with us here at Witter farm came in and made a diagnosis about 2 things; whether the cow is pregnant or not, and if they are not, then he will determine if it is worth inseminating soon or not. This process is done by a rectal palpation where alone it can be identified as early as six weeks after conception or insemination. On the farm, we are responsible for keeping track of if a cow is in heat. This is a term used to show a cow is in estrus.
A couple things we look for to know a cow is in heat is restlessness, calling/being vocal or mounting/allowing other cows to mount. It is important to note whether the cow underneath is just standing there or not because she is most likely in heat and soon to be inseminated or bred if she is not resisting. We normally do heat checks about twice a day for 20 minutes, once in the morning and another in the afternoon.
After a cow has been artificially inseminated then the vet is able to look on an ultrasound machine as early as 19 days into ovulation and determine if she may be pregnant or not at all. This is because a cow is on a 21 day estrous cycle, which is similar to a woman’s menstrual cycle. After ovulation occurs, a follicle gives rise to a corpus luteum which is fully functional by about day 15 in the cycle. This structure is the reason for a possible pregnancy because there is a specific signal that prevents it from regressing and dying. That means if by the end of the cycle the corpus luteum is still there then this signal was activated and it is still going to thrive.
Once the cow has been detected for a possible pregnancy it does not become for sure until a couple more vet checks, usually 2 weeks apart on the farm. The length of pregnancy of a cow is also similar to that of people. It is about 9 months or 279 days. After calving the baby is with the mother for only a limited time before we have to place them elsewhere for their safety of not getting stepped on. She is then milked for her colostrum and that is given to the calf.