IMO there's to many variables to keep to a regular feeding system (cold weather, a hard race previous week, how much energy they expend exercising, training). By far the easiest way to make sure they're getting what they require is to add a % of barley in their feed, if they eat all plus the barley they're telling you their appetite hasn't been satisfied. I feed them in pots in their boxes but have a try on the loft floor which I hand feed on if they require more. They'll tell you a lot by watching them exercise, if after 15-20 mins they land and remain motionless, preening themselves or drop down onto the ground picking around they've not been fed enough. Carbs heat the body.