Jessica, the kids you are referring to that wouldn't eat grain, were dam raised boer kids that were 4 to 5 month olds. They had only been on mom and pasture. They had NO CLUE what grain was, the owner of the goats only fed cow range cubes to the adults and that was a "treat". So, they thought we were trying to poison them with the feed. We tried every feed (including goat, rabbit, chicken, horse, alfalfa pellets, etc.)/grain (corn, oats, etc.)/top dressing (powdered kid replacer which is VERY sweet smelling, calf manna, etc.), acting like a goat eating it, pretending of course, to give them the hint of what it was for (that was a big laugh for my kids, lol), nothing worked, we were told to try restricting hay to see if they would at least try it. After a few days of them not eating... it was apparent that nothing was going to work. They would rather eat the occasional leaf that fell into their pen or shavings off the floor than food. We worked with them for a month and a half and all we saw was lost body condition, heartache, and many $$ down the drain. :/
BUT! you are raising those kids and they see you as the feed source. Whatever you give them tastes good, right?! So, it shouldn't be a problem if you put it out for them early on so they can nibble on it and get a taste for it. The problem that I had, no one that I talked to, breeders of meat or dairy goats, or even the county extension agent (who raises boers herself) had EVER heard of my problem with those goats!