The kanji and the word are the same. This word is a bit broader than cow though, and can also be used to be bull and ox.
Since this word is made up of a single kanji, it uses the kun'yomi reading. Here's a mnemonic to help you to remember it:
You're leading the cows around the field. To get them to move, you yell out "USH, USH, USH!" (うし) because you have a speech impediment and want to say "MUSH MUSH MUSH." Go ahead and say this out loud, yelling it if you can.
There are many cows.
Which would you like, a beef steak or a chicken steak?
My pet is a cow.