Published online by Cambridge University Press: 27 March 2009
Few problems have been reported with the use of the isotope dilution technique for measuring volatile fatty acid (VFA) production in the rumen of sheep. However, early studies carried out in this laboratory, using a standard technique (Leng & Leonard, 1965) showed serious limitations associated with losses of activity from the infusates. Subsequent inquiries suggested that other laboratories had experienced similar problems (J. D. Sutton, National Institute for Research in Dairying, Shinfield, and D. E. Beever, Grassland Research Institute, Hurley, personal communication). When solutions of [U-14C]Na acetate, [l·14C]Na propionate and [l·14C]Na butyrate obtained from the Radiochemical Centre, Amersham, were each diluted with deionized water to provide 0·5 μtCi μtmol/ml (hereafter designated 14Ac, 14Pr and 14Bu respectively) and left to stand at room temperature for 6 h, losses of activity of C, 15 and 3% respectively were found.