Thanks for letting me know.

If the same space aliens that designed my surplus barrels designed yours, try this to open them. The small openings are threaded. You can probably buy a specially-designed storage drum opening tool on-line, but pliers work great, too. Take a pair of pliers, close them, stick them nose-down into the center of the small, 3-inch lids, then open them until the jaws hit the outside of the lid, and turn counter-clockwise. The jaws of the open pliers will catch on the tabs in the lid and unscrew it. With the pliers almost fully opened up, you get lots of torque on the handles. You probably won’t understand what I’m talking about until you try it, but it works.

The three-inch opening probably isn’t sufficient for inserting and extracting chicken feed, so cutting the top off was a good idea. I hope hinge idea works. If not, you might try screwing blocks of 2×4 to the bottom of the lid you cut off. Place them so the blocks touch the insides of the barrel when the lid is on. With luck, friction will keep the lid in place.