In Tractate Beitza Perek Baiz Mishnah Ches it brings down a Machlokes between the Chachamim & Reb Elazar Ben Azaryah:
"Can you scratch or scrape the body of an animal with a metal comb on Yom Tov?"
Chachamim say "no", while Reb Elazar Ben Azaryah says "yes".
Rashi says in Tractate Shabbos 107 - this is because it will make the animal bleed, which is prohibited under the melacha of slaughtering.
BUT AREN'T YOU ABLE TO SLAUGHTER ON YOM TOV SINCE IT'S FODD PREPARATION?!?!