I would look at the stalk bales as mostly bedding, have hay out free choice and greatly reduce the grain.  I have weighed 5 gallon buckets full of my treat grain and they are around  35 lb gross so your 30 lb grain per bucket is very close. That. Would mean your 700 lb calves are getting close to 20 lb/day grain which is a lot. They are ruminants. Cattle eat around 2.5 to 3% of their weight every day and yours are getting that almost completely from grain. Grain should be a much lower percent of their diet.

Jim