Well, you need to tell us some more, Steephills. Are they nursing their moms, or are you bottle feeding? Beef-type steers, or dairy-type, or X-breds, or ?? And where are you -- cold weather country, or warm weather country. You 'gotta give us a little more information, please.
When I was training oxen/working steers I kept the grain portion of their ration at around 1% of their weight. Kept them growing well and didn;t get them so high that they were hard to train. That was with free choice quality grass hay or pasture.
Rural Heritage is a good source for information http://www.ruralheritage.com/front_porch/index.htm http://www.ruralheritage.com/ox_paddock/index.htm