Is the ruminal fluid (digesta) an ideal solution?

I previously discussed the significance of dissolved carbon dioxide (dCO2) and CO2 holdup on ruminant health and function in my original work (Laporte-Uribe, 2016). I used the example of Moate et al., 1997 to illustrate the link between diet composition and ruminal dCO2 concentrations, which can influence the risk of bloat.

In this updated version, I delve into the physicochemical characteristics of rumen fluid, specifically the relationship between dCO2 and ruminal partial pressure of carbon dioxide (pCO2). According to Henry's law, in ideal solutions, the amount of dissolved gas in a liquid is proportional to the partial pressure of that gas above the liquid. However, Moate et al., 1997 revealed a logarithmic relationship between ruminal pCO2 (%) and dCO2 (mM/min), indicating that rumen fluid is not an ideal solution. This implies that conventional methods based on Henry's law may not accurately measure ruminal dCO2 concentrations.

Modern feeding practices can exacerbate these non-ideal conditions, leading to CO2 holdup and elevated dCO2 levels. This, in turn, increases the risk of CO2 poisoning (SARA) and other nutritional disorders. By monitoring CO2 holdup, we can proactively prevent these diseases and optimize ruminant health through precision ruminal fermentation.

The relationship between the ruminal pCO2 (%) and the rate of CO2 ROE (mM/min) an indirect method for dCO2 estimations, the information was extrapolated from Moate et al. (1997), see Laporte-Uribe (2016) for details.