Comparative Availability of Phytin and Inorganic Phosphorus to Rumen Microorganisms, in vitro.

Summary Results of cellulose digestibility in a series of studies utilizing calcium and phosphorus depleted suspensions of rumen microorganisms confirm the calcium requirements of rumen microorganisms, and indicate phytin phosphorus utilization to be significantly more sensitive than inorganic phosphorus to calcium levels and ratios. Data suggest decreased phytin phosphorus utilization at the wider Ca/P ratios to be more directly related to a chemical effect than to enzyme inhibition, and provide basic evidence of the critical need for careful consideration of levels as well as ratios in the adjustment of calcium to phosphorus ratios for ruminant animals on high phytin rations.