This sound effect can be found on Series 1000 Sound Effects Library, which was made by Sound Ideas. It's a shorter, and higher-quality version of ANIMAL, DONKEY - BRAYING, SNORTING. It's also a high pitched version of Donkey Brays MediumT PE024701. It was originally a Valentino sound effect called Donkey Brays & Snorts which can be found on Major Records - Sound Effects Volume 13. It's also the exact same track as Animals - Donkey braying 01 from Network Sound Effects Library.