You should target feeding 2.5% to 3% of the steer's body weight. You aren't anywhere near that right now. Although a word of caution- feeding 3% (or feeding a ration that is too heavy on corn) can hinder hair growth.
At 860 pounds...
2%= 17 pounds of grain per day
2.5%=21 1/2#
3%=25 3/4#
Remember that it typically takes about 7 pounds of GRAIN to equal 1 pound of GAIN.
Start increasing his ration by about 1/2 to 1 pound per three days (assuming that he will eat his current ration). You will have to do the math to see how quickly you need to increase it, BUT be careful not to increase it too quickly.
If you are feeding Honor Show Chow Finishing Touch...that is a pretty hot ration, which is what you need at this point. If the steer is not eating well, check to see that the feed is fresh. I used to feed Honor Show Chow and ran into trouble with that. I honestly would not suggest switching feeds at this point, because it will slow down your gain (unless of course you just can't get him to eat what you are currently feeding).
Try soaking some beet pulp shreds in warm water for a bit and then mix it into the feed. I've never had a steer or heifer or cow that did not go nuts over beet pulp!! Also-the extra fiber is good to give bulk and fill to the steer. It should replace the Depth Charge. Sometimes the animal gets too full on the Depth Charge and won't eat the whole ration because it makes his gut swell. Beet pulp does that too, but not to the extent that Depth Charge does.
Watching the steer's manure is a good way to monitor how they are handling the increase in feed intake. If it gets too loose, increase the beet pulp. Be careful about increasing the ration too rapidly if his manure is too loose. I add a tablespoon of baking soda to the ration on occasion if I see really loose manure with bubbles.
Vita Charge paste or gel caps will help, and Sure Champ is great to help keep a calf on feed!
I've fed both the Heavy Weight and ADM Healthy Glo (which is Stabilized Rice Bran). The Healthy Glo is a much better product in my opinion. It is also a good additive for hair. I have to get it at a different supplier than the rest of my feed, but it is worth it! Start with half a pound per day and increase to a pound per day. Warning- this may make the steer's manure loose at first. This is actually a product fed to horses, but plenty of folks feed it to their steers and even their heifers on occasion. It comes in both meal and nugget form. I feed the meal. This also helps the cattle consume their entire ration.
Make sure the steer always has access to clean, fresh water at all times. Feed him free-choice GRASS HAY. Do not feed the good stuff like alfalfa. The free choice hay helps to stimulate the gut and adds fiber. MORE hay=MORE grain intake (although there are those who believe that less hay=more grain intake).
GOOD LUCK!