Abstract
Two orchardgrass hays (early cut (EOG) and late cut (LOG)) and alfalfa hay (ALF) were fed to three rumen cannulated sheep once a day to investigate the changes in fiber content of particulate matter as size reduced in the rumen. Rumen digesta samples were collected at various time after feeding, and were fractionated by particle size (LP:>5600, MP: 5600-1180, SP: 1180-300, FP: 300-47μm) using wet sieving technique. The fiber components (NDF, ADF and ADL) contents were measured for each particulate fraction. Cellulose content of LP and MP for EOG and ALF decreased with time after feeding. The ADL content of all fractions for ALF and of both LP and MP for EOG increased with time after feeding; but the other fractions had no change over time. For all hays, cellulose content tended to decrease as particle size decreased, whereas, ADL content was on the reverse trend. Their extent of change, however, differed among three hays, of which ALF was the greatest and LOG lower than EOG.
