Old MacDonald Duck (1941)
Donald owns a farm; he sings Old MacDonald while feeding the animals. He goes to milk Clementine the cow, but she's not in the barn: she's up a tree, nibbling on leaves. She floats down, and the milking goes well. Her tail stops swinging; Donald leans over to check and it swats him in the face. The milking is again interrupted by some flies buzzing around; Donald pulls his hat over his head and the fly gets inside, in the confusion, Donald gets his hat and pail confused. Donald starts firing milk at the fly in retaliation, but the fly manages to get the cow to send Donald flying.