Not bull fighting. COW fighting.
You're looking at the "Battle of the Queens", or "Combats de Reines" as they'd say. In the Aosta Valley in Switzerland, this is an annual tradition.
It turns out that every herd of cows has a "queen" cow that the rest of the herd will respect. They don't elect this "queen" -- they just lock horns and fight it out, and top cow gets the rights to the best grazing land. And it turns out that this little battle happens every year when the good grazing land becomes available.
The Swiss cow-herds took this to the next level when they started having arranged battles between the top queens of different herds. The cows took to it naturally because two queen cows, both wanting to lead the whole crew, are naturally oriented to do battle. (We see the same thing in humans.) And now it's a big event every Spring, with judging and categories and refereeing and such. Here's a shot from further out to show the scale of it.