
I used to keep my open feed bags in trash cans as well. I had some extra trash cans so it was a ready solution to keep the rodents out. However, like you mentioned, you have to do a lot of bending over as the feed is removed from the bag to get down to the bottom. Over the years, this has become less tolerable for me.
Also, the trash cans just took up a lot of space in the garage because I had the big round trash cans.
Over a period of time, I have collected a number of free 5-gallon buckets from Harbor Freight. Each bucket holds 25# of feed, or half of a normal feed bag. I stack one bucket on top of the other, so no more bending over to reach the feed. When the top bucket is empty, I move it to the bottom and place the other bucket on top that is full of feed.

 I know it's not a big thing, but it just reduces the effort I need to dish out my daily ration of feed for the chickens. Anything I do to reduce bending, at my age, is a benefit. And, if for some reason I need to move my feed around in the garage, picking up a 5-gallon bucket full of feed only weighs 25#. The 5-gallon buckets are much smaller than the trash cans I used before, so I have more free space in my garage for other projects.
If you need to buy some lids for your buckets, then I have found the best deal for the 
easy off lids at WalMart...
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I use those easy off lids for the buckets that I am currently using for feed access. For longer term storage, I use some of my regular lids, but they are pain in the butt to take off.

 Unfortunately, I have yet to find any source for free lids for the 5-gallon buckets. But I have enough lids in my collection that I get by. Most uses of my 5-gallon buckets don't need a lid. Mainly, I only use the lids on my chicken feed buckets.

 If anyone knows of a place where you can get 5-gallon bucket lids for free, please let me know. Thanks.