Pregnancy Checking of Cows
There are a few ways that preg-checking can be done.
1. Sight: After the cow has been bred, you will start to see her sides grow as she gets further into pregnancy. By her third trimester she will look like a barrel with a head and four legs. After she has concieved she will not come back into heat for a while (cows' estrous cycle is 21 days long, so she will go into heat every 21 days). The best way to tell is to wait for 45 days after she has conceived and during that time, see if she has gone into heat a couple times. If not, then she's pregnant.
2. Bumping. This is done when she's 4 to 5 months into her pregnancy, and if she is tame enough you can go up to her and scratch her back. If not, don't bother with this method. On her right side (not her left, as this is where the rumen is) on the belly closest to her back leg (but not too close, still along the belly), thump her belly and keep your hand there to feel for any movement. Chances are you will feel movement, and will know if she's pregnant or not if you have also been paying attention to her like I mentioned in #1.
3. Rectal exam: This is THE BEST way to determine pregnancy, and it is not only used on cows but also horses. It should mostly be done by someone with a lot of experience preg-checking animals, but it can be done by you if you know what you are doing and what you are looking for. The cow has to be restrained in a headgate and chute before you do this. You need to "glove up" with a shoulder-length glove first, then pour some lubricant on your hand. Form your hand like a puppet with its mouth closed (all 4 fingers at a 90 degree angle from the knuckle joint with the thumb held straight out under the fingers, touching the first and middle fingers), and push into the anus; be sure to go in with your fingers pointing downwards at a slight angle to penetrate the anus. Then you will slowly have to push yourself in up to your shoulder. Now once you are in you are feeling the uterine horn through the rectal wall. You will have to be strong for this, and may have to withdraw your arm to take out some feces that have accumulated in there. Now point your hand down and feel for a head, nose, hooves, or anything that resembles a fetal calf. If you feel something, a movement against your hand or anything like that, then the cow is definitely pregnant. Most cows are preg-checked when they are 3 to 5 months along, some even 45 days into gestation. It is good to preg-check as early as possible so you can cull out the ones not bred (or are open) before the rest of the herd calves out.