I think AAOK is probably correct on this. If you have a spring born calf that you just brought home, he should be weighing somewhere between 500-600 lbs (on average) and its pretty easy to get a healthy happy little dude to eat 20 or more lbs of feed a day. Additionally, what helps is that calves are more inclined to eat when the weather is cool and if you are light next summer and the heat hits, its hard to put it on them.