Submitted to: Agri Practice
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/1997
Publication Date: N/A
Interpretive Summary: Diagnosis of acidosis in feedlot cattle that die is difficult, leading to the assertion by some consultants that acidosis is the most misdiagnosed disease of feedlot cattle. Previous studies have indicated that ruminal pH and lactic acid concentrations, variables often used to diagnosis acidosis, are poor indicators of the disorder in ruminants that have been dead for several hours. This further complicates the diagnosis of fatal acidosis in feedlot cattle and sheep. The use of the feed additive monensin has been shown to reduce the incidence of acidosis in feedlot cattle. Supplementation with monensin seems to increase ruminal pH and decrease ruminal lactic acid production. However, it is not known what effect monensin has on postmortem ruminal changes. This manuscript summarizes an experiment conducted to evaluate the effects of dietary monensin concentration on postmortem changes which occur in the rumen of sheep that die of acidosis. This study indicated that the feeding of monensin attenuated the postmortem decline in ruminal pH apparently by its effects on postmortem accumulation of lactate and volatile fatty acids in the rumen. These results confirm earlier studies which indicate that ruminal pH and lactic acid concentrations, common variables used to diagnose acidosis, are poor indicators of fatal acidosis in animals that have been dead for several hours. These results can be used by veterinarians to get a better diagnosis of the cause of death in feedlot cattle.
Technical Abstract: This study was conducted to determine the effects of dietary monensin on post-mortem ruminal changes in sheep. Monensin feeding did not significantly affect ruminal pH values or concentrations of total volatile fatty acids and lactate during the first 6 to 8 hours post-mortem. However, at 18 to 24 hours post-mortem, animals fed monensin had higher ruminal pH values and lower ruminal lactate concentrations than controls. The feeding of monensin did attenuate the post-mortem decline in ruminal pH, apparently via its effects on post-mortem ruminal accumulation of lactate and VFA. These factors should be considered during field and laboratory necropsies of cattle and sheep.