Heat treatment of rapeseed meal increases phytate flow into the duodenum of sheep

The effect of heat treatment on duodenal how of phytate, i.e., inositol hex aphosphate, from rapeseed meal was studied in four sheep fitted with duoden al cannula. The rapeseed meal was fed untreated, heated at 133 degreesC (H1 33) or heated at 143 degreesC (H143) for 3 h. Levels of phytate and its hyd rolysis products, i.e., inositol tri-, tetra- and pentaphosphates were meas ured in duodenal digesta. Phytate was the major form of inositol phosphate (IP) in the duodenal digesta. Heat treatment increased daily flow of inosit ol hexaphosphate, inositol pentaphosphate, and inositol tetraphosphate into the duodenum. Approximately 22, 37 and 55% of dietary phosphorus in the fo rm of IPs was recovered at the duodenum of sheep fed untreated, H133- and H 143-treated rapeseed meals, respectively. Results suggest that heat treatment of rapeseed meal increases flow of phyt ate into the duodenum, decreasing the digestibility of dietary phytate phos phorus for sheep. (C) 2000 Elsevier Science B.V. All rights reserved.