Individual identification of pigs during rearing and at slaughter using microchips

Improved retention rate with small compared to large microchips.Improved retention rate with late than early injection of microchips.Ear tags caused more tissue damage in the pig ear than injected microchips.Unacceptably high proportions of lost microchips and ear tags.

Identification of individual pigs is essential for management, traceability, breeding, trading and disease control in commercial pig production. Conventional identification methods used for pigs, such as ear tags and tattoos, are not sufficiently reliable due to losses and code erasing. This study investigated the retention rate, functionality and tissue damage of microchips compared with conventional electronic ear tags and assessed the effects of chip size and pig age at microchip injection. A larger proportion of small (95.2%) than large (82.5%) microchips were readable throughout the rearing period (p<0.031). It was better to inject microchips when the piglets were 9–10 weeks old compared with 1–2 weeks (p=0.058). Ear tags caused significantly more tissue damage than microchips (p=0.001). However, although microchips met the requirements of an identification system for pigs that is unique, easy to read, does not produce apparent disturbance to the animals and causes minimal pathological changes, the proportion of lost microchips was unacceptably high. Further research on chip type, pig age at marking and marking site is needed to find suitable methods for identification of individual pigs.