I feed once a day, usually in the late evening, as then they have had a few hours awake and active to clear up any stashes. I do one adult handful of dry mix per 3 rats. Fresh food is a bit harder to quantify, but the food for 3 rats fits into one of those little Gu glass pudding ramekins, heaped (it’s basically five or six fresh ingredients, and one dime-sized piece per rat, although there is quite a lot of day to day variability). Those are my starting points for healthy adults, then I adjust it for each group depending on whether they are leaving food regularly (I aim to have them clear everything within 22 hrs) and whether there are juvenile/ old/ill rats who need dietary adaptations, and by assessing the rats' condition. I want shiny, firmly muscled vital rats – if they look dull, feel skinny, or get flabby prior to late middle age, then something is nutritionally off.