Keep him going with the same ration you are giving today but with a liquid fat top dressing. There is a zillion different ones out there and they are all about the same, we have have a fairly local one by us that we like a lot. Then when he hits that magic 1300 lbs mark (probably in about a month or so), or whatever weight he is finished at, put him on a 4-5 lbs. beet pulp, 1-2 lbs. wheat bran, 1-2 lbs. of oat grotes, and the most important 2 scoops (there is a scoop that comes in our bags I can check the exact measurement if needed. About a cup and a half i would guess) of non-medicated milk replacer along with 3 lbs. of his normal grain. This ration will put the brakes right on one and will not sacrifice the finish by making them stale or by making them starve. The variance in the beet pulp, wheat bran, and oat grotes are depending on how much you have to play with weight-wise and if you need to take any weight off or not. If you have any questions, pm me, and i can be of help or detail. Feeding cattle is definitely a science and every calf gains and converts feed differently but this is a mix we found to work really well for us through the years to help hold one.