Research data suggest that if tricalcium phosphate equals 100% available, monosodium and mono-ammonium phosphorus would have a value to 115 to 125%, dical and monocal phosphorus would be 105 to 110%, bone meal (non-ruminant) at 90%, and rock phosphates lower. Thus, the availability differences are small, and price per unit of phosphorus should be the driving factor.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
