Ninety-eight steers were implanted subcutaneously in the anal region with identification transponders to determine the feasibility of recovering the transponders at slaughter. Groups of 20, 19, 19, 20 and 20 steers were slaughtered 1, 35, 71, 105 and 175 days after implanting. At the first slaughter, 7 transponders were lost when the anal sphincter was removed during hide removal. At subsequent slaughterings, leaving the anal sphincter intact and removing it with a 150 mm section of rectum at the viscera table resulted in the recovery of at least 17 transponders in each group. Those not found in the rectal section were recovered from the carcass. No migration of transponders from the implant site was observed. Histological examination of tissues surrounding the transponders indicated that encapsulation had begun by 35 days after implant.
