CASE STUDY: Retention and readability of radio frequency identification transponders in beef cows over a 5-year period 1

The objective of this study was to evaluate failure (loss or inability to read) of radio frequency identification (RFID) ear tags in beef cows over a 2- to 5-yr period under ranch conditions. One of 5 types of RFID tags (Allflex HDX, Allflex FDX, Y-Tex FDX, Z-Tag FDX, and Destron FDX) was applied in the ear of a total of 4,316 cows on 4 separate locations (ranches). Tags were evaluated at approximately yearly intervals for either 2 (ranch 1), 3 (ranch 2 and 3), or 5 yr. Percentages of tags that were lost or that failed to read were 1.4, 1.6, 3.7, 5.1, and 5.0 for the 5 consecutive annual evaluations, respectively, when averaged across ranches and RFID tag type. Cumulative losses of 3.0, 6.0, and 19.8% were observed when averaged over all tag types after 2 (all 4 ranches), 3 (3 ranches), and 5 yr (1 ranch). A ranch by tag type interaction was evident for failure of the 2 types of tags evaluated on all 4 ranches; a greater proportion of Allflex HDX tags were lost than Allflex FDX tags at ranch 4 (36 vs. 4%) but not at other ranches (4.7 vs. 5.1% cumulative loss-fail rate for HDX and FDX). This interaction may be due to differences in tag placement. Tags were placed in the top of the ear at ranch 4 but were attached between the second and third ribs of the ear at ranch 1, 2, and 3. Results indicate that loss of RFID tags increases with time after application and may exceed 5% after 3 yr.