Here at Koberstein Farms, We use RFID Tags in the beef animals to track their movements and to monitor their performance and growth.  We have used several types of programs and different equipment but the one that works the best for us is the Archer Unit and FAST EID Software sold by Fort Supply Technologies, www.fort-supply.com  In the photo below you will see the unit we use along with all the accessories.  The data is saved in an excel format spreadsheet so that the data can then be downloaded to a regular computer or laptop.  We can send this data to any breed association for registering the cattle or to our source and age provider for verification of the animals birthdate.  The folks at Fort Supply have been very helpful with everything and are always on call if you have any questions. The unit is weather proof, water proof, and very durable as I have dropped mine several times and it still works great.