The feasibility of using passive injectable transponders in field operations for individual identification of sheep in Italy

This trial evaluates the feasibility of using passive injectable transponders (PITs) in field operations by testing identification procedures on 185 one-year-old Biellese ewes reared under nomadic farming conditions. Commercial PITs of 3.85 ± 0.05 mm × 31.2 mm were used at two application sites, the armpit and the retro-auricular region. The two application sites were compared taking into account the ease of injection, animal reaction, injection duration, inflammatory response, PIT readability at up to 12 months post-injection and PIT recovery at the slaughterhouse. The injection site influenced the reaction of the animal and the ease and duration of the injection, but it did not affect the palpation and the reading findings during the rearing period. The injection site also influenced the PIT retrieval at the slaughterhouse depending on the operator who recovered the PIT. The readability values observed at the end of the observation period for both injection sites (83% in the retro-auricular region and 79% in the armpit region) were too low to be suitable for long-term animal identification. In addition, the failed retrieval of PITs at slaughter, determined the destruction of 40 (22%) carcases to avoid any risks in the food chain. These findings suggest that the limited use of PITs is indicated when other methods of electronic identification cannot be employed, while a wider application of the device tested in the present study is not recommended in farming practices.