Studies on the degradation of inositol phosphates in the rumen of cattle

In plant seeds phosphorus (P) is predominantly stored as inositol phosphate, also called phytate. Ruminal microorganisms are able to degrade inositol phosphates and thus enable the ruminant to utilize the released P. High feed intake and subsequent high passage rate in dairy cows presumably reduce degradation and lead to an increased phytate flow in the duodenum. The objective of this project is to determine dynamics and extent of ruminal phytate degradation at different levels of phytate intake in dairy cows. Based on the results of a digestibility trial in dairy cows with different P sources, phytate-P degradation of different feeds is detected by batch culture and in situ-incubations.  Donor animals are fed with rations differing in levels and sources of P. In order to quantify ruminal degradation it is necessary to obtain postruminal digesta samples. Another objective of this project therefore is to establish gentle omasal sampling technique via the rumen cannula.