Saw a version of this at a craft fair. I don't have any animals, so I've been asking people who do to save the feed bags for me. Feed doesn't come in burlap bags anymore. Now they are made of the weaved plastic like the reusable shopping bags. Sturdy stuff!
Martha was the first to get a bag to me. She doesn't even have chickens....yet... but she emptied her feed into a bin just to get the bag to me. I hadn't even told her what I was going to do with the bag. She was delighted when I returned the bag to her in its new shape!
This is about the size of a large grocery bag, with extra long handles.