Evaluation of electronic identification transponders implanted in the rumen of cattle

The performance of electronic identification transponders encased in ceramic capsules inserted into the reticulo-rumen was assessed in 3 groups of cattle: 1059 two-year-old feedlot steers, 11 penned calves and 46 grazing calves. Insertion of capsules presented little difficulty and at slaughter, examination of the reticulorumen showed no visible signs of damage to the reticulo-endothelium due to the capsules. The retention rate of the capsules was 100% in adults when slaughtered 55-107 days after capsules were inserted. All Losses of capsules from calves occurred before calves were 21 weeks of age. Transponders were successfully read both in the live animal and in the body on the slaughter chain. All transponders in the reticulorumen of grazing calves were functioning normally up to 46 weeks after being implanted. At slaughter, capsules were recovered easily with no risk of contaminating meat or by-products. Small steel metallic objects near the capsule appeared not to affect the reading distance of the transponder.