With this mod, you can only melee attack livestock (AnimalEntities that have the tag #knifestock:livestock) while holding knives (items tagged with #knifestock:knives).
By default, the items tagged are anything tagged with #c:knives, and minecraft:debug_stick, which makes it impossible to hit livestock with this mod alone. In other words, this mod is for modpack use only.
Ranged weapons work as normal.
I made this because BetterCombat makes selecting livestock to slaughter more tedious because of the large area-of-effect of weapons.