GPS ear tags are becoming more popular on the farm for livestock tracking. You could actually put GPS tags on any asset on the farm to track at all times. This ABC Rural article from Australia focuses on tracking sheep but the tags can be used on all types of livestock. The story mentions that the current tags are too large for the sheep, but I expect them to shrink in the near future.
As I mentioned in a past post, this is about greater farm asset tracking for efficiency and disaster recovery, to know the locations of all assets before and after thunderstorms, snowstorms, and other disasters; natural or man-made. Asset tracking minimizes losses and reduces insurance claims, it also allows record audits for regulating agencies.