Your emergency preps should include hay for your horses, enough for a month. Keep it dry and away from sunlight.
Natural events, such as earthquakes, wildfires and hurricanes may force businesses to close for weeks. Transportation may be interrupted. Power and fuel may be in short supply.
Your back may go out, where you can’t even scoop poop, let alone stack hay. (You do stack your own hay, right?)
The quality of the hay may deteriorate over time, so after a period of six to twelve months, rotate it out with fresh bales. But always keep a one-month supply on hand and don’t touch it unless there’s an emergency.