Have you been excercising the steer, if not I would try lots of excercise to stimulate an apeptite, this worked well for me with my steers in high school and helped develop muscle tone on my steers too, I would also try molassass and cooked corn, mixed in ration, with some soaked beat pulp.
We always found that some competition helped. We never fed out a single animal. If it's possible for your situation and you have somewhere to go with the extra calf, I would suggest that you feed 2 or more animals at the same time. We also had better luck hand feeding several times a day as opposed to keeping feed in front of them all the time. Mike