Animals eat less feed, not more, when protein is limited. So, feeding too much protein or energy with reduced levels of the other results in less growth, the opposite of what is wanted. Some owners feed high levels of protein, and not enough energy, with the mistaken idea that weanlings will grow faster. It's imperative that there is more calcium in the ration than there is phosphorus. More phosphorus than calcium often occurs when weanlings are fed large amounts of grain or concentrates and little hay.
Grains are generally higher in phosphorus while hays are higher in calcium.
Alfalfa hay is a good choice. There is evidence that feeding extra copper and zinc may be beneficial to better-quality bone. Providing supplemental vitamin A to weanlings may be helpful too.