The effect of drying temperature on in vitro dry-matter digestibility and water-soluble carbohydrate content of perennial ryegrass varieties

In official forage grass variety trials in the UK, herbage samples are drie d at 100 degrees C or more to facilitate quick drying of the large numbers of samples that are currently needed. When assessing herbage quality, howev er, 80 degrees C has been recommended as the highest temperature that can b e used during drying without serious deterioration. Herbage from six perenn ial ryegrass varieties, which were known to show a range of variation in in vitro concentration of digestible dry matter (DMD) and water-soluble carbo hydrate concentration (WSC) during the vegetative phase of growth, was drie d in an oven with forced ventilation at 100 degrees C and at 80 degrees C b efore analysis. Mean DMD over all varieties was slightly lower [6 g kg(-1) dry matter (DM)] and mean WSC over all varieties was considerably lower (24 g kg(-1) DM) at 100 degrees C. Varieties differed in mean DMD over both dr ying temperatures by 37 g kg(-1) DM and in mean WSC by 63 g kg(-1) DM. Ther e was, however, no significant interaction between variety and drying tempe rature for either DMD or WSC. Although drying at the higher temperature und erestimated both DMD and WSC, it did not significantly alter the ranking of varieties or the range among them.