Retention of different sizes of electronic identification boluses in the forestomachs of sheep1,2

Abstract

Twelve types of electronic identification ruminal boluses of different dimensions were used to obtain a model for predicting their retention in the forestomachs of sheep. Boluses (n = 1,662) were made of ceramic materials, and their dimensions varied in o.d. (9 to 21 mm), length (37 to 68 mm), volume (2.5 to 21.0 mL), and specific gravity (0.85 to 3.91). Each bolus contained a half-duplex, standardized, glass-encapsulated transponder (32 x 3.8 mm). Boluses were administered to sheep (n = 1,497) of different ages by using the appropriate balling guns, and their retention under semiintensive conditions was recorded for at least 2 yr. When a bolus was lost, the sheep was rebolused with a heavier bolus. All sheep wore 2 plastic ear tags: one for the official control of health programs and the other for farm use. To determine the anatomical limit for a bolus passing through the gastrointestinal tract, the size of the reticulo-omasal orifice was measured in 46 adult sheep (male, n = 14; female, n = 32) that died by causes not related to bolus administration during the experiment. No signs of disease or growth alteration were detected in the bolused sheep. Total ear tag losses during the experiment period were 7.5% on average. Bolus retention (5 to 100%) varied according to bolus features and age of the sheep, but it showed a plateau after 18 mo. Inadequately dimensioned boluses were regurgitated or passed through the gastrointestinal tract and were excreted with the feces. The diameter of the reticulo-omasal orifice in adult sheep differed between male and female (23.1 and 21.8 mm, respectively; P < 0.01) and was greater than the o.d. of the retained boluses. Retention rate was predicted from bolus weight and volume by a logistic regression (R2 = 0.997; P < 0.001). When retention data from the literature (59.0 to 100%) were included in the model, the adjustment was slightly lower (R2 = 0.967). As a result, the minimum bolus weight estimated to reach a 99.5% retention rate in sheep varied between 16 and 45 g when volume varied between 3 and 22 mL, for boluses with a specific gravity between 2.0 and 5.2. In conclusion, bolus retention rate in sheep varied dramatically according to their features. For safe and efficient retention of electronic identification boluses in sheep, boluses of small volume and diameter (e.g., < 15 mm) with specific gravity and weight greater than 3.0 and 20 g, respectively, are recommended.

Performance of electronic and visual ear tags in lambs under extensive conditions in Turkey

“…Thomas et al (2006) reported that the overall loss of e-ETs was 9.9 % for sheep in 4.5 months and 19.2 % for lambs in about 3 months, and these lost rates were unacceptably high for official use. Elec- tronic and visual ear tag losses observed in the study were lower than those reported in the literature (Caja et al, 1999;Conill et al, 2002;Rusk, 2002;Ghirardi et al, 2006;Thomas et al, 2006). …”

“…Readability of ear tags (96.8 % for e-ETs and v-ETs, 93.5 % overall) placed on the 1/2 part of the ear did not reach the ICAR value, whereas readability of ear tags placed on the 1/3 part of the ear was 99.0 % for e-ETs and v-ETs, and 98.1 % overall at 1 year after tagging as recommended by ICAR. Ghirardi et al (2006) observed a 3.3 % annual loss in plastic ear tags in sheep. Carne et al (2010) also reported 4.3 % of e-ETs and 3.0 % of v-ET losses at 1 year in dairy goats, which was unsatisfactory for official use according to the ICAR requirements.…”

Electronic and visual identification devices for adult goats reared in semi-intensive system

“…Readings of ruminal bolus were taken immediately before and after administration to identify precocious losses, as recommended by Ghirardi et al (2006). During 1-ruminal bolus; 2 -big ear tag; 3 -small ear tag.…”

“…Electronic ruminal boluses comply with the requirements established by ICAR (2007) and, therefore, are considered safe and effective means of identification of cattle and sheep (Caja et al, 1999;Ghirardi et al, 2006). However, high variability has been observed for retention rate of electronic rumen boluses in goats (Pinna et al, 2006;Carné et al, 2009a;Carné et al, 2009b).…”

Traceability in the meat, poultry and seafood industries

“…Ear tag losses were 7.5%, while bolus retention varied with bolus features and sheep age. Boluses of 16-45 g, with a volume of 3-22 mL, and specific gravity of 2.0-5.2 were estimated to have a 99.5% retention rate, while boluses of less than 15 mm, specific gravity higher than 3 and weight greater than 20 g were recommended for use in sheep (Ghirardi et al ., 2006b). Ceramic mini-boluses with these parameters did not cause feed intake or growth differences and had 100% recovery at slaughter (Ghirardi et al ., 2007).…”