Abstract
Washed suspensions of rumen microorganisms were used in a series of studies to determine the effects of adding various levels of phosphorus in different chemical forms upon cellulose digestion. Monosodium orthophosphate, vitreous sodium metaphosphate, acid sodium pyrophosphate, and calcium phytate were the sources of phosphorus used. Marked increases (P<.05) in cellulose digestion occurred when levels of 20 to 100 mcg. of phosphorus per ml. of medium from each source were added. Phosphorus in all of the chemical forms studied appeared to be utilized by rumen bacteria. Results of experiments in which all of the chemical forms of phosphorus were assayed simultaneously showed that slight but significant differences in cellulose digestion occurred when all sources were added at levels to supply 20 and 40 mcg. of phosphorus per ml. of basal medium. However, all sources of phosphorus produced about the same microbial cellulolytic response when 60 mcg. of phosphorus per ml. of medium from each source were added. The relationship of the in vitro results to results of availability studies of these same phosphorus sources with sheep was discussed. Copyright © . .