Mid 2000s, I played with combining RFID tags w/ cow magnets. (A relative had a cow magnet side hustle and asked for my input.) At the time, one livestoct mgmt

Mid 2000s, I played with combining RFID tags w/ cow magnets. (A relative had a cow magnet side hustle and asked for my input.) At the time, one livestoct mgmt strategy was to add tags to ears. Then add readers to the thresholds cows move thru. Alas, a semi common failure mode is sometimes those ear tags get ripped out. So some cows don't get tracked. Apart from the challenges of using RFID (eg cost, range, interference), any new tag would require support by the livestock mgmt stack. Vendor lock-in and all that. Or create our stack. Which I was not inclined to do.