I heard this story through oral tradition (an artist friend and Jodorowsky expert related the tale to me.) Essentially, the story goes, no one wanted to slaughter all of the lambs necessary for the procession scene in The Holy Mountain and so Jodorowsky took it upon himself in service of his vision (aka "getting the shot") breaking the necks of the multitude of lambs required.
Has anyone else heard this story? There is a discussion of the scene here and this is a New York Times response to the film from 1974, but I can't find anything on Snopes debunking the claim.