I think what your local cattle guy may have been trying to tell you is that the expense of making them fatter may end up costing you profit. Creep feeding is more likely to pay off in years when calf prices are up and feed prices down. Cattle prices are down sharply from the last 2 years, so you are unlikely to recoup your investment In that creep feed. You need to remember that lighter calves bring more dollars per pound than heavier calves.
Here is an example :
Say that you can wean 7 month old 500 pound calves on your grass, but if you creep feed for the last 90 days you can increase weaning weights to 650 pounds. We will assume the 500 pound calves bring $1.50 a pound or $750. The 650 pound calves will not bring the same pound price. Depending on your local market you may even find it more difficult to sell the heavier calves. If you are now selling to a stocker buyer, he may want them lighter because he makes his money on the weight they gain for him before they hit the feedlot. If we assume those 650 pound calves bring $1.30 they would be worth $845. That is $95 more or $.633 per pound for those extra pounds. In this example, unless your costs in feed and labor are less than $95 for those three months of creep, you are losing money by creeping.
If you are selling registered cattle as breeding stock, then fat sells, and creep feeding may pay off. If you can put together a set off uniform calves to fill a pen at a feedlot maybe those extra pounds that you put on with creep could also pay off. If you are direct marketing beef you can get them finished faster with creep and that might increase profits. If you sell your calves at weaning, in most years creeping calves will not be cost effective.