Cattle are not really built to handle a lot of dietary fat. Is the creep for an entire pasture or as a diet for growing and marketing show calves? In a creep ration, you should focus on developing the calf in terms of protein, energy, minerals, vitamins etc. Bloom, in my experience, is related to all of that. Fat could serve a part in supplying energy, but high amounts will limit rumen function and I might guess that high fat could delay rumen development if introduced too early. I do not feed a high fat creep or add oil to a growing calf's diet. I am not sure if you are asking about adding fats and oils directly or if you want to use high oil ingredients. I have used high oil corn and extruded beans in limited amounts with lactating cows and in show rations. To answer your question, I would focus on protein without regard to fat. If you need a good creep look up AAOK's creep ration on this board. His WORKS and you can afford to feed it to an entire pasture if you feel the need.