For Brianp: The rule of thumb is 2-3 percent of their body weight, so a 500 lb calf should be eating between 10 and 15 lbs. Not only feeding the right feed, like a developer, but working them into the feed.
Most show calves have been on creep so they have had some grain, when you first start feeding a new feed you start out slow, 4-5 pounds a feeding with plenty of hay. You monitor their stool, appetite, and watch for bloat, you slowly add feed to each feeding until you work them up to the 3 percent of their body weight. If they start to get to loose, slow down on their eating or you start to notice an abundance of undigested grain in their stool, you back off on the grain for a few days and then continue increasing the feed. It can take up to 2 to 3 weeks to get them where you want them. The same with a calf that has never been on feed, just start with 2 to 3 pounds, you do it slowly, over time, and you monitor them through the process.
If you are switching feed and you have both the old and the new feed, you slowly add a couple of pounds of the new and subtract the same amount of the old until they or fully on the new feed.
Most bagged feeds will give you feeding instructions and most if not all will have you feeding 2-3 percent at full feed.