Electronic identification with injectable transponders in pig production: results of a field trail on commercial farms and slaughterhouses concerning injectability and retrievability.

A nationwide electronic system for the identification of all pigs is a means to achieve a tighter control of livestock and meat in the Netherlands. In order to examine the use of electronic identification transponders, two field trails were performed. Transponders supplied by three separate companies were tested on pigs on commercial farms. In phase 1, each device was examined on separate farms and in phase 2, the three devices were tested on each farm. A total of 3,436 and 5,947 transponders from the different suppliers were injected in the base of the ear at weaning in phase 1 and 2 on seven and five farms, respectively. The following aspects were examined: technical labour for injection and reading, readability of the transponders, impact on tissues at the injection site, and retrieval of the transponder after slaughter. After instruction the farmer was well able to inject a transponder in a restrained piglet. The results show that in phases 1 and 2 1.6% to 7.3% of the transponders were unreadable at retrieval in the slaughter line, which is significantly (p < 0.05) higher than the required maximum loss of 1%. The 1.6% failure rate in phase 1 involved transponders from a single supplier. Loss of identification was associated with rejection after injection, expulsion during inflammation and technical failure. Three weeks after injection on average 0.6% of the piglets had an observable inflammation and at the time of retrieval pus was found around, on average, 1.2% of the transponders. An average of between 37% and 88% of the transponders were retrieved in the slaughter line from the base of the ear in phases 1 and 2. The other transponders were retrieved medial or caudal to this position. This positional variation meant that it was not consistently possible to remove the transponder from the carcass within the required 4 second time period. It was concluded that the systems should be improved before recommending their introduction on a large scale, because the variation in readability and location is too high.

Effects of injecting electronic transponders into the auricle of pigs.

Electronic transponders (3 x 18 mm) were injected into the base of the auricle of 69 10-day-old pigs, 111 four-week-old pigs and 24 six-month-old pigs, to examine the procedure of injection in the auricle, the tissue reaction and the ease of removal from the carcase. The injection was difficult in the 10-day-old pigs, but was easier at four weeks. One of the 204 transponders were lost and five of them appeared to be broken. Only one gilt showed some exudate around the transponder. The transponders could easily be removed when the pigs were slaughtered by cutting off the ear. The position of the transponder was significantly (P < 0.05) more ventral in the animals injected at 10 days old than in those injected at four weeks. The mean thickness of the connective tissue capsule around the transponders increased at first (P < 0.1) and then decreased when they were injected into 10-day-old pigs but decreased (P < 0.1) from shortly after injection in the pigs injected at four weeks old. After five months, the capsule in the animals injected at 10 days old was on average significantly (P < 0.01) thinner than in those injected at four weeks.