A few of you asked for more info on what the heck this thing was. They are used to keep track of which numbers the announcers have called for penning. Really handy the farther you are in the order of go.
Each number will only be used once until all the numbers have been run through. Every time a new team goes in and their number is called you slide the little 'button' over.
Let's say you are on the7th team to go in. You've been paying attention and seeing how the cows react to the teams. You look down at your cattle counter and see that 1, 3, 4, 6, 8, and 0 are all slid over. That means your cattle number will be either 2, 5, 7 or 9. If you've been paying attention really well you may notice something like the cattle that are tagged 5 have been extra feisty and hard to deal with or that the 2s really like to run hard.
Hope that helps y'all some :)