[Naturella]

The largest I have seen is Victor, in 30 lbs for grain free, and 40-50lbs for grain inclusive. Sometimes they do a double special, i.e. you get 2 30-lb bags (for a total of 60 lbs) for a reduced price. I think the website is http://www.sportdogfood.com

Also, Dr. Tim’s – grain free comes in 30lbs, and grain-inclusive in 35lbs.

But yeah, haven’t really seen a 50-60lb bags of food…