Source
This item can be looted from most level 10-37 boars.
Highest drop rate, pre-Cataclysm, was from level 13 - 15 Mangy Mountain Boars in Loch Modan. However, those boars have been removed from the game, and the Loch Modan Mudbelly Boars do not seem to have the same high drop rate for this item.
Boar Ribs as an ingredient
This item is used to make: