What is most often used to track livestock on large farms and identify each animal Individually?

Radio-Frequency Identification (RFID) is the most prevalent technology for tracking and individually identifying livestock. Small, passive or active RFID tags are attached to animals, typically as ear tags. Each tag stores a unique identification number. When an animal passes near an RFID reader (e.g., at a feeding station, water trough, or gate), the reader wirelessly captures the unique ID. This allows for automated, individual tracking of location, health, feeding patterns, and other critical data, which is essential for managing large herds efficiently.

A. Photodiode sensors are used to detect light intensity and are not suitable for uniquely identifying individual animals.

C. 802.11 wireless radios (Wi-Fi) are too complex, costly, and power-intensive for simple, per-animal identification on a large scale.

D. Thermistor sensors measure temperature and are used for health monitoring (e.g., detecting fever), but they do not provide a unique identity.

1. CWNP, "CWISA-103 Certified Wireless IoT Solutions Administrator Official Study Guide," (2020). Chapter 1, "What is IoT?", discusses various IoT verticals and use cases, including smart agriculture (agritech), where RFID is a foundational technology for asset and livestock tracking.

2. Kamilaris, A., & Prenafeta-Boldú, F. X. (2018). "Deep learning in agriculture: A survey." Computers and Electronics in Agriculture, 147, 70-90. Section 3.1, "Livestock Monitoring," explicitly details the use of RFID tags for the identification and tracking of individual animals to monitor their behavior and health. DOI: https://doi.org/10.1016/j.compag.2018.02.016

3. Tzounis, A., Katsoulas, N., Bartzanas, T., & Kittas, C. (2017). "Internet of Things in agriculture, recent advances and future challenges." Biosystems Engineering, 164, 31-48. The paper reviews IoT technologies in agriculture, identifying RFID in Section 2.2 as a key technology for "animal identification and traceability," which is fundamental to modern livestock management. DOI: https://doi.org/10.1016/j.biosystemseng.2017.09.007