It has been established that in ruminants there is a circulation of water-soluble
phosphorus from the blood, through the saliva into the rumen and back via the
small intestine. A high water-soluble phosphorus concentration of the ruminal
ingesta is thus maintained irrespective of the diet or the phosphorus level of the
blood. There is, therefore, no indication that the supplementation of a phosphorus
deficient diet with water-soluble phosphate will have any effect on ruminal function.