The paper presents design of in-vivo ruminal pH probes and compares them with current state-of-the-art alternatives. The main advantage of the proposed solution is a novel, patented approach for transmitting measured data from bovine rumen to a server or cloud via a re-transmitter placed in a collar device at the animal’s neck. Additionally, in comparison to the commonly measured values such as ruminal temperature and pH, the proposed solution enhances the data set with oxido-reduction potential (ORP) values measured by the ruminal probe and activity data acquired by a MEMS accelerometer located in the collar device.