Thanks for the responses.
I used to free-feed, but, haven't done that for a very long time (over a year). I set their food bowls down and when they were enjoying their food, they ate it quickly and I picked up the bowls. Now...I have been leaving the bowls out longer and longer, as they aren't eating the food like they had been. Probably a mistake. I'll try setting them a limit (like the 20 mins. suggested). Just wanted to state that I don't free feed! Cindy W.