Post-ruminal phytate degradation in sheep

This experiment was conducted to study phytate (inositol hexaphosphate) degradation in the post-ruminal digestive tract of sheep. Three sheep were fed a diet containing 20% rapeseed meal at intervals of 2 h for 5 days and then digesta were collected from the abomasum, small intestine, upper large intestine and lower large intestine. Levels of phytate and its hydrolysis products (i.e. inositol tri-, tetra- and pentaphosphates) were measured in digesta samples. Approximately 35% of dietary phosphorus in the form of inositol phosphates (IPP) reached the abomasum. Passage of IPP did not differ markedly between the abomasum and the small intestine. The flow of IPP into the lower large intestine was less (P<0.05) than that into the small intestine but did not differ between the upper and the lower large intestine. Consequently, 12% of dietary IPP was recovered from the lower large intestine. Results suggest that phytate is partly degraded in the large intestine of sheep but the major site of phytate degradation is the forestomach.