Abstract: The invention relates to a measuring device for the measurement of at least one physiological parameter of a farm animal's organism, whereby the measuring device is placeable in the gastro-intestinal tract of livestock and comprises the following components arranged in a casing: at least one sensor for the measurement of at least one physiological parameter of a farm animal, at least one transmitter with antenna for the wireless transmission of information, at least one control unit for controlling the measuring device, and at least one power supply device for the measuring device, whereby a hollow protective guard is provided inside the casing which covers at least the power supply unit in order to protect it from mechanical impact.