An animal health monitoring system, comprising: a ruminant bolus transponder (103, 201, 401) comprising at least one physiological sensor, a microcontroller with memory, a low frequency radio frequency identification (RFID) transceiver, a low frequency antenna, a high frequency radio frequency transmitter and a high frequency antenna; a high frequency radio frequency transceiver device (104b, 301, 402) comprising a microcontroller, an environmental temperature sensor, and a high frequency radio frequency transceiver; at least one base station (105, 106, 403) comprising a high frequency radio frequency transceiver; at least one low frequency scanner; wherein the high frequency radio frequency transceiver device (104b, 301, 402) is proximally located to the bolus transponder (103, 201, 401); wherein the ruminant bolus is configured to periodically emerge according to a first time interval from a low power dormant state and record data comprising at least one physiological sensor measurement associated with time and date data; wherein the ruminant bolus is configured to store several measured data using the memory of the microcontroller in the ruminant bolus; wherein the ruminant bolus is configured to periodically emerge according to a second time interval from a low power dormant state and transmit the several measured data stored in the memory to the proximally located high frequency radio frequency transceiver device (104b, 301, 402) via high frequency RF transmission via the high frequency antenna; and wherein the ruminant bolus is configured to be activated by the low frequency scanner via the low frequency antenna, wherein the high frequency radio frequency transceiver device is configured to initiate communication with the base station at scheduled intervals and convey the several measured data to the base station, or wherein the base station is configured to broadcast polling requests to said high frequency radio frequency transceiver device. a ruminant bolus transponder (103, 201, 401) comprising at least one physiological sensor, a microcontroller with memory, a low frequency radio frequency identification (RFID) transceiver, a low frequency antenna, a high frequency radio frequency transmitter and a high frequency antenna; a high frequency radio frequency transceiver device (104b, 301, 402) comprising a microcontroller, an environmental temperature sensor, and a high frequency radio frequency transceiver; at least one base station (105, 106, 403) comprising a high frequency radio frequency transceiver; at least one low frequency scanner; wherein the high frequency radio frequency transceiver device (104b, 301, 402) is proximally located to the bolus transponder (103, 201, 401); wherein the ruminant bolus is configured to periodically emerge according to a first time interval from a low power dormant state and record data comprising at least one physiological sensor measurement associated with time and date data; wherein the ruminant bolus is configured to store several measured data using the memory of the microcontroller in the ruminant bolus; wherein the ruminant bolus is configured to periodically emerge according to a second time interval from a low power dormant state and transmit the several measured data stored in the memory to the proximally located high frequency radio frequency transceiver device (104b, 301, 402) via high frequency RF transmission via the high frequency antenna; and wherein the ruminant bolus is configured to be activated by the low frequency scanner via the low frequency antenna, wherein the high frequency radio frequency transceiver device is configured to initiate communication with the base station at scheduled intervals and convey the several measured data to the base station, or wherein the base station is configured to broadcast polling requests to said high frequency radio frequency transceiver device.