You all are aware, no doubt, that a cow has 4 stomachs. I will not bore you with the names, I can't spell them anyway, but did you know the baby calf has an esophagus groove to direct the milk into the proper stomach? The other stomachs do not start functioning until a little later.
Bet you didn't know baby calves are born with pads on their sharp little hooves to protect their mother's birth canal. These pads wear off easily as the little calf struggles to stand up.
The adult cow encircles grass with her tongue and then cuts it off with her bottom teeth, she has no top teeth in front. She then swallows without chewing. Later, at her leisure, she will "burp" up her cud and chew it with teeth set back in her jaw. This cud will then be swallowed passing into another stomach.
This stomach is loaded with tiny "bugs", or micro's, which breakdown and eat the food. There are bugs that eat only corn, bugs that eat only hay etc. When the bugs die off they are actually a source of protein for the cow. So when the farmer feeds the cow, he is actually feeding the bugs in the cow's stomach. It is important that the pH of the stomach is favorable for the bugs.
Cows are fed bypass proteins which the bugs cannot breakdown. These then pass on down the line and are digested later giving the cow a more steady supple of protein which is necessary for todays high milk production.
The tail is the cows mood barometer. Unlike the dog, a "wagging" tail does not make a happy cow. Not being milked in a timely fashion, dinner off schedule, calves bellowing, and flies are the major causes of crabby cows. Crabby cows generate crabby farmers.