Hi! The best way to add calories without energy is to add fats. You can add corn oil or soy oil to each feeding. You want to start off slow with the introduction, usually over 3-4 weeks as the body needs to adjust so it can adequately digest the additional fats. You can potentially feed him one cup up to twice daily. Another bonus to fat supplementation is that it has no effect on cecal or colonic pH so there really are not any side effects. If he is picky with the top dressing there are some feeds that are considered “fat supplemented”. These are feeds that are labelled >3.5% fat so look for a feed that has 8-10% crude fat.