Using different rumen boluses for the electronic identification and milk recording of dairy sheep

A total of 368 sheep were used to compare three electronic boluses for individual identification and milk recording in a dairy flock of the University of Wisconsin-Madison (USA). Boluses consisted of ISO transponders: B1 (70 g, plastic), B2 (75 g, ceramic), and B3 (16 g, ceramic). Bolus readability was checked during two years by using appropriate handheld transceivers. Administration and reading times averaged 68 and 17 s, respectively. Final readability varied by bolus type (B1, 5.0%; B2, 100%; and, B3, 99.0%). The Bl bolus was insufficiently readable, but the B2 and B3 were very effective in sheep identification and milk recording.