The dog will never starve to death, so you don't have to worry too much about miscalculating. I think 1-2 cuts per dog per day to keep them fed.
There used to be a bug that the dog wouldn't eat unless you were there to watch them eat, and I'm not sure if it's been fixed. You should try leaving them with a pile of meat and seeing how much they eat and whether they're hungry when you get back.