To achieve ending 1, you need to have a really high donkey brain level before you enter the farmhouse for the first time. The safest way to do that is to bray a bunch before going in; if you already have a really high level and go to the silo or graze, you'll get pushed over the edge.
Low meaning less; the donkey behaviors boost a number that I generally refer to as donkey brain; when that number reaches certain thresholds, that's what triggers the different texts, behaviors, and endings. To start this specific scene, you want to go to the Edge of the Farm basically right after running from Faye in the farmhouse, then wait in the Crossing the Wheat scene for the event there to start.