Having long stem forage is very important for a horse as it aides in the digestion process. If a person is feeding 15 lbs of long stem forage and wants to also feed some forage pellets, then simply replace what is taken away pound per pound. If you feed 15 lbs of long stem forage, take away 5 lbs of long stem forage and replace with 5 lbs of forage pellets. You would still be feeding 15 lbs of forage total.