Lost in translation: from reticulum to rumen pH

By Francesca Harding

Scientific Officer 

A recently published study by one of our research customers explores how reticulum pH values measured using the eCow bolus can be converted into rumen ventral sac pH values. Established SARA thresholds are based on ventral sac pH measurements but the eCow bolus measures the reticulum pH. Therefore, in order to understand the bolus data in terms of SARA thresholds, a translation needs to occur.

SARA thresholds 

  • Below pH 5.8 for more than 5-6 hours per day 
  • Below pH 5.6 for more than 3 hours per day 

Conventional determination of the SARA risk using these thresholds can include rumen  sampling methods, such as rumenocentesis or rumen canula. These methods are static, providing only a single, snapshot measurement. As the SARA thresholds are also based on a change over a period of time and this cannot be quantified using static measures. The reticulo-rumen is a dynamically changing environment and so static measurements are only of limited use.

Figure 1- The structure of the Reticulum and Rumen, the first two chambers in a ruminant stomach. 

This where eCow’s bolus provides the simplest and most effective solution. Our indwelling pH bolus continually monitors the reticulum pH, and is less invasive than conventional static measures. To understand this in the context of SARA thresholds, the bolus data can be translated into rumen values. This was recently examined by a team at the University of Veterinary Medicine in Vienna. 

In this study, using eCow bolues, the reticulum pH was found to be consistently higher than the rumen pH. To translate the reticulum values into rumen values the researchers used linear regression analysis. This is a commonly used type of simple statistical analysis where one or more variable is used to predict another variable. Using this technique, the authors determined that a SARA threshold of a rumen pH of 5.8 is equivalent to a reticulum pH of 6.0. In general, the reticulum pH is approximately 0.2 pH units higher than the rumen pH.

Figure 2- Linear regression analysis comparing the pH measurements from the rumen to the pH measured in the reticulum. 

Figure taken from Neubauer, V. et al., 2017

Another important finding of the study was that indwelling  boluses can detect dynamic changes in the reticulum, which cannot be done with conventional measurement methods. This highlights the benefit of using the eCow bolus during times when the reticulo-rumen pH is particularly prone to fluctuations. These fluctuations in pH can be a problem during times of dietary change and can result in various health problems, including SARA. An indwelling pH bolus is the best way to monitor these changes and can alert the user to problems far before any clinical signs become apparent.

This exciting research highlights the real benefits of using the eCow bolus to diagnose SARA. By understanding that the reticulum pH is 0.2 pH units higher than the rumen pH, data from our boluses can be translated to rumen values. This can then provide a more reliable insight into the SARA risk using the established thresholds.

Find out more information about how our bolus could benefit your farm or request a quote today.

The full study can be read here or accessed via our library

Neubauer, V., Humer, E., Kröger, I., Braid, T., Wagner, M., Zedali, Q. (2018) Differences between pH of indwelling sensors and the pH of fluid and solid phase in the rumen of dairy cows fed varying concentrate levels. Journal of Animal Physiology and Animal Nutrition, 102: 343-349. 

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