Anger is used as a protective mechanism to cover up fear, hurt or sadness. Anger becomes the predominant feeling behaviorally, cognitively, and physiologically when a person makes the conscious choice to take action to immediately stop the threatening behavior of another outside force.
Donkeys are grazing animals, just like horses. In the wild, they mainly graze on grass. However, they also eat straw, tree leaves, bark, some flowers and brambles. Donkeys that are are raised by humans are fed hay (dried grass) when the grass is not growing. Donkeys love eating bread, peppermints and ginger biscuits, but these rot their teeth! Facts About Donkeys.
Thanks for the answer request. I'm not a vet so i don't really know. My guess is that what you're smelling are sulphurous compounds associated with garlic and onions. Perhaps review what your donkey is eating. Some vegetables such as cabbage and other Brassicas can cause gas and sulphurous smells in humans, perhaps donkeys too.