If your steers  weigh 800-1100 lb (avg 950 lb) right now and you want to ship a group in late August (4 months or 120 days from now), you should be able to put at least 2.3-2.5 lb per day on them on pasture with no implants.

So that would give you a likely live weight at the end of August of 950 lb + 120 days x 2.4 lb/day on grass = 1238 lb for the first group on pasture only.  If you supplement with corn/barley/pea you should be able to hit close to 3 lb/day which would give you a late August weight of 950 + 120 x 3 = 1310 lb.

I guess I don't see anything wrong with those numbers without implants. And your October group especially, if kept on the same pasture and/or feed, should have no problem finishing without implants.

I guess it depends on your cattle and what sort of "finished" weights you are aiming for or are possible with them.

jmho.

Jim at Dawn