A wireless network for measuring rumen pH in dairy cows

The objective was to develop a continuous pH monitoring system for dairy cows based on wireless sensor technology. The requirement to pass body tissue with low energy resulted in the use of the 124 kHz frequency for the measuring bolus and a two radio repeater that used 2.4 GHz for further communication to a gateway. Messages from two of the three investigated boluses were missing for periods of four to ten minutes while two is intended. This can be overcome by proper tuning of radio power. The boluses proved to stay well in the reticulum part of the rumen of three cows during a one week experiment. The combined temperature and pH sensor, based on ISFET technology, showed clearly fluctuations in temperature due to drinking of the cows. Dynamics of pH are also visible. Further research will be required to determine how pH measurements by a bolus are to be compared to other methods used so far in research. The used pH sensors showed considerable drift and elimination of this problem has priority for further research and development.