I'm sorry, I don't have much details to give, but lets starts from basics i remember:

- It played in Music Television in Finland, late 80's or early 90's, @ Saturday or Sunday morning (either 05.00 or 06.00am), i remember it cause my parents weren't that happy when i woke up that early to watch some cartoons.

Can't say much details from show, pretty much all i remember, is that main character was big red bull (or bison), who was either sheriff or cowboy, and landscape was something like Texas or Grand Canyon. I just have image in my head that big red bull standing and patrolling landscape, with his revolvers ready

Thanks already :)

"The Wild West C.O.W.-Boys of Moo Mesa", perhaps? It was first aired in 1992 on ABC, and it may have been replayed in Finland on MTV.

Plot summary from Wikipedia:
"Like many cartoons during its time, C.O.W.-Boys dealt with a mutation of some kind; in this case, an irradiated meteor struck the late 1800s Western plains creating a miles high mesa shrouded in clouds. Everything trapped on top of the mesa was "cow-metized" by the light from the "cow-met" and "evolved" into a "bovipomorphic" state. Inspired by old tales of the Wild West, this new bovine community developed to the point where they emulated that era's way of life, including the requisite ruffians and corrupt sheriffs. However, their knowledge of Wild West living was limited, and as such, many things about their culture had to be improvised to 'fill in the blanks'. The concepts of steampunk and Weird West were utilized throughout its run.
The series focuses on trying to keep justice in the frontier territory. The lawbreakers were too much for the corrupt regulators of Cowtown - Mayor Bulloney and Sheriff Terrorbull - to handle by themselves. Helping them out, whether they wanted it or not, were a group of peacekeepers known as C.O.W. Boys, short for "Code of the West." Led by bull Marshal Moo Montana, the C.O.W. Boys also included the Dakota Dude and the Cowlorado Kid. The muscle-bound Marshal and his deputies had their hands full with various ruffians and outlaw gangs that plagued the otherwise peaceful town."

http://www.retrojunk.com/details_tvshows/222-wild-west-cow-boys-of-moo-mesa/
http://www.retrojunk.com/tv/videos/222-wild-west-cow-boys-of-moo-mesa/989/#intro

Yeah, I think that's what I was looking, thnx m8 :)