I've been having a rat problem for a little over a month. I found one in the chick starter feed bag last night crawling out quickly. When I looked inside the feed sack, I saw some rat droppings. I'm going to buy some Behren's galvanized steel trash cans tomorrow.. four trash cans for each of the different food. Do I need to dump my current stock of feed or can I use the rest? It's a lot of money in feed. Also, is a 20 gallon big enough for one bag of chicken feed or do I need to buy the 30 gallon cans?