I have two greyhounds, weighing between 29 kg and32kg, they have Wheatabix with skimmed milk every breakfast (with an egg each beaten into it every second day), plus I feed them two tins of Butchers grain-free each per main meal. But they also have dishes with a dry complete food in dishes available as top-up, should they feel hungry throughout the day. They have never over-eaten, so have remained at a steady weight throughout the 7 years i have owned them.