I think it's a brand thing. The chicken feed I get comes in a paper bag. The neighbor gets a different brand and it comes in the plastic burlap bag. Cat food and dog food are starting to come in the plastic burlap bags too.
I make mine with the bag going around the bottom and sewing the sides on. I have had them loaded down with heavy jars full and not had any problems.
I have posted the directions, step by step with pics on both BYCows and BYChickens. If you need them.
My DH says when his father made donuts he would watch the weather first. He claimed there was a certain type of weather to make donuts in. Is this true? I know in candy making you need to watch the humidity but, had never heard of watching the weather for donuts.