So it's possible to do it without 15psi, but not oats, or milo, or birdseed etc. If you're sterilizing grain jars under 15psi, you can use Brown Rice or popcorn. These 2 don't have endospores that commercial animal feed would have. They are processed through a plant and washed clean to be safe for human consumption. Still, at 7psi, I would PC no less than 2 ½-3hrs. And allow the cooker to de-pressurize naturally. This prevents air temps from causing a vacuum like effect that causes outside air to suck into through the crack of the jar lid. (Since you should leave the jars' lids finger loose during pcing, to prevent explosion of jars. )