I've started mixing the pellets, rolled grain (barley at the moment), BOSS & calf manna. The additives used to be given on top of their pellets but then they would dig for the special bits and waste a lot of feed. Now it's all mixed together which is easier to feed and for some reason they don't dig in it when it's all mixed together.
As for percentages it's not exact, but around here there's two (or two and a half) scoops of pellets to one of rolled grain. Then about a half scoop of BOSS to two of those and a half scoop of calf manna to two of those. Two scoops pellets, one of grain, two scoops pellets, one of grain, half scoop of BOSS, repeat the above then add the half scoop of calf manna and mix all together. The resulting feed is primarily the green of pellets, with a lot of grain mixed in with occasional seeds and calf manna. Nursing does get more of the BOSS and calf manna added to their rations. About every third or fourth day it's primarily fresh forage, which cuts down on feed costs as well as gives them more fiber.