Funny, but good reply. Answer is "no". We have numerous movies that don't have horses and/or rodeo in them.
If you are seeking a movie with boys, cows, and cowboys, I might recommend Open Range. Neither Brando nor Nickleson are in it, but Costner and Duvall did well at holding my interest. Missouri Breaks with Brando and Nickleson was a good show, but The Shining was Nickleson's best after One flew over The Cocoos's Nest. I am looking for About Schmidt with Nickleson and Kathy Bates. Kathy Bates first got my attention in Misery.
I find it interesting that some of these folks have their career paths carved for them early on. If you watch his real early stuff (The Raven in 1963) he is about the most wooden actor you've seen. I watch that movie and wonder how he ever got cast in anything else...and that was his 7th flick. Brando was OK in Apocalypse Now, but of course, Sheen had the larger role. He played in more than one western...funny, you don't think of him as being the cowboy type.
Do not like Brando movies at all. He's just too contrived to be believable. Nicholson is a classic Jerseyan. We're all nuts. He turns it into an art form.