Quantitative Studies on the Dynamics of Carbon Dioxide and Bicarbonate in the Rumen

Abstract

The increase in fermentation rate which accompanies the feeding of more readily digested diets as compared with roughage diets fed to ruminants leads to large increases in gas (CO₂ and CH₄) and acid produced in the rumen. The latter results in a reduction in the buffering ability of rumen contents unless salivary flow or bicarbonate movement into the rumen increases with fermentation rate. Where the acidity of rumen fluid contributes to an increase in CO₂ produced by acidification of salivary HCO₃-. The rate of gas production and degree of accumulation of HCO₃- in the rumen are factors which dictate the severity of the condition of bloat. A study of the dynamics of the bicarbonate buffering system of the rumen with particular reference to the sources and routes of input of C into the HCO₃-, H₂CO₃, CO₂ and CH₄ pools is required to fully understand the bloat syndrome. ... The results of this study have confirmed that the feeding of high concentrate diets results in an increase in the amount of CO₂ produced that has to pass through the gas phase of the rumen, usually via the liquid phase. The feeding of high concentrate diets also results in a reduction in the bicarbonate buffering ability of rumen contents. With manipulation of the diet, it is possible to increase and stabilize the buffering capacity of the rumen.