I was prepared to give
Mountain Of The Cannibal God the benefit of the doubt during the snake/monkey scene until the DVD revealed that the monkey was forced in front of it.
Mondo Cane is definitely one of the milder ones.
Africa Addio is absolutely vile and totally unwatchable at times. The gorgeous music makes the footage seem even worse. Incidentally Riz Ortolani composed the scores for both and would later score
Cannibal Holocaust (and the equally animal-and-Candice Bergen-unfriendly
The Hunting Party).
Haven't seen
Brutes & Savages but
Savage Man, Savage Beast is similarly revolting in parts (though the goat sucking the hippy girl's breasts is just bizarre). I've got
Goodbye Uncle Tom but haven't got round to warching it yet. Not an animal snuff movie but not exactly a glowing light on Political Correctness either.