Loss of forestomach motility in sheep experiencing ruminal lactic acidosis is not dependent on duodenal acidification by lactic acid.

Reticuloruminal motility, duodenal myoelectrical activity, and the pH and lactic acid concentrations of ruminal and duodenal contents were monitored in rumen fistulated sheep that were intraruminally loaded with finely ground wheat (50 g/kg). Following ruminal loading, reticuloruminal motility was enhanced. However, within 6 hours of loading, forestomach motility was impaired and within 9 hours ruminal stasis occurred. During loss of forestomach motility, lactic acid concentrations in ruminal contents increased and may, in part, have contributed to the decrease in pH of ruminal fluids. The levels of lactic acid within duodenal contents also rose, however, the pH of duodenal contents remained unchanged. During the loss of reticuloruminal motility, premature regular spiking activity (RSA) and/or abnormal patterns of migrating myoelectric complexes (MMC) were not observed on the duodenum. These findings indicate that loss of forestomach motility in ruminal lactic acidosis may not be a consequence of acidification of the proximal duodenum by lactic acid produced in the forestomach.