Minecraft wiki entry for Donkey, associated text: Donkey's health ranges from 15–30, but tends toward the average 22–23. Displayed hearts are health, divided by two, rounded down. A donkey with an odd number of health points (15, 17, 19, etc.) does not display the last half-heart. If the donkey has lost one fewer health point than the inflicted damage and did not regenerate, it has an odd number of health points, otherwise, it has an even number of health points.