Development of a ceramic bolus for the permanent electronic identification of sheep, goat and cattle

Retention rate and digestive and performance effects of ceramic boluses (66 x 20 mm, 65 g) enclosing passive transponders (32.5 x 3.8 mm) were studied in three experiments. Reading distances of transponders inside and outside the boluses (n = 10) did not vary. In the first experiment, a total of 2452 boluses were applied to 74 lambs and 808 ewes, 16 young and 67 adult goats, 1138 calves and 349 cows. Plastic balling guns were used to insert the boluses and their effects were evaluated during 3 years or until slaughter. Time needed for application and recommended live-weights (LW) depended on animal category (sheep, 24 s and > 25 kg; goats, 26 s and > 20 kg; cattle, 19-240 s and > 30 kg). Application in calves was possible during the first week of life. Retention rates were 100, 98.8 and 99.7% in sheep, goats and cattle, respectively. The location of boluses in the reticulum was checked with hand-held readers and verified by X-ray in a sample (n = 4) of each animal category or directly in cannulated cows (n = 3). Transceivers were interfaced with electronic scales for automatic weight recording. Dynamic reading efficiency was 100% in race-ways with a frame antenna (94 x 52 cm). Health and performances were not modified by boluses. An average of 93% of boluses were found in the reticulum at slaughter. Recovery rates and times varied according to animal category (lambs, 100% and 5 s; ewes and goats, 100% and 8 s; fattened calves, 91.3% and 12 s; dairy cows, 72% and 14 s). In the second experiment, two groups of adult ewes (control, n = 5; bolus, n = 5) were housed in individual pens and fed forage ad libitum. Mean forage intake and nutrient digestibility were not varied by the ceramic boluses. In the third experiment 45 fattening male lambs (20 kg LW) and 20 replacement ewe-lambs (30 kg LW) were used. Fattening lambs were divided into two groups and assigned to the treatments (control, n = 25; bolus, n = 20) until slaughter (25 kg LW). In spite of the difficulties observed in the force-feeding of boluses in eight lambs (40%), average daily gain and reticulum-rumen mucosa were not altered. Ewe-lambs were also assigned to the treatments in two groups (control, n = 10; bolus, n = 10) and monitored until first lambing or 1 year old. The weight, body condition score and reproductive performance were not affected by boluses. In conclusion, the use of the ceramic bolus is recommended as a safe and tamper-proof method for electronic identification of ruminants once the animals have reached a weight where successful administration is possible. Moreover, boluses proved to be useful for dynamic reading and automatic weight recording on farm conditions. (C) 1999 Elsevier Science B.V. All rights reserved.