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ANIMAL PRODUCTION |
University of Sydney, Faculty of Veterinary Science, 425 Werombi Road, Camden, NSW 2570, Australia
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Key Words: ear tag • electronic identification • pig • traceability • weaner
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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). The Primary Industries Ministerial Council has endorsed National Performance Standards that have been supported by the pig industry with the aim of improving traceability systems for pigs after farm-gate. These standards require the location(s) of a suspect pig within the last 30 d and its cohorts be provided to authorities within 24 h of it becoming infected or suspected to be infected with foot-and-mouth disease (Animal Health Australia, 2005).
The Australian pig industry currently uses tattooing to identify pigs for sale or slaughter. A review of pig identification legislation in Australia illustrated an inability to track movements of weaner pigs (<25 kg of BW or 10 wk of age; Schembri et al., 2007). Currently, Victoria is the only state where weaner pigs are required to be identified by an ear tag.
Australian studies have shown that pig production in peri-urban areas (defined as a region within a 100-km radius of a capital city or within a 20-km radius of a rural center with a population of more than 30,000 residents; ABS, 2005) tends to be undertaken within small holdings (Schembri et al., 2006). Pigs in these types of production systems may change ownership several times between birth and slaughter and are bought on the basis of live weight and quality (Schembri et al., 2006). Traceability in these circumstances is challenging, and this type of animal may present an increased risk of health problems to other producers, consumers, and the livestock industry (Madec et al., 2001; Schembri et al., 2006).
The objectives of this study were to assess performance of 4 identification devices currently on the market, assess the ease of application and cost-effectiveness of each device, and determine the incidence of adverse effects from application of these devices.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Animal Housing and Management
This study was undertaken on a multisite commercial pig farm in New South Wales, Australia. Pigs (Large White x Landrace x Duroc x Pietrain) were selected after weaning at 4 wk of age from a 2,300-sow farrow-to-finish farm. To compare the performance of the identification devices under different housing and management conditions, a number of experimental progeny (n = 224) remained on the home farm for the duration of the experiment. These pigs were reared in small groups of 30 pigs per pen in concrete-based pens with experimental and nonexperimental pigs (site A). The remaining proportion of experimental pigs (n = 170) were transported 31 km from the home farm to a grow-out site (site B). Experimental weaner and grower pigs were penned with nonexperimental pigs in 1 large group of 825 pigs in a deep-litter system with rice hulls and cereal straw bedding, whereas the finishers were kept in 10 conventional pens in a concrete floor shed. Pigs at site A were grouped into pens based on sex and BW at weaning (3 to 4 wk of age) before onset of the experiment. These pigs were resorted by size as they moved to the grower and, later, the finisher stages. In contrast, pigs at site B were not sorted by size, with both sexes housed together in 1 large pen. A description of the rearing conditions at site A and B is presented in Tables 1 and 2, respectively.
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Pigs were slaughtered over a 3-wk period from 14 wk and 17 wk after application from site A and B, respectively, at 75 to 80 kg of BW in an export accredited, commercial abattoir. Transportation to the abattoir was carried out by trucks specified for pig transportation following the Model Code of Practice for the Land Transport of Pigs (PISC, 1998). Pigs from site A traveled 8 km, whereas pigs from site B traveled 27 km to the export accredited slaughterhouse.
Identification Devices and Application
A total of 394 pigs were randomly assigned after weaning at approximately 4 wk of age to 6 treatment groups, and each animal was identified with 2 identification devices. Device application took place over 1 d, at the time of weaning in the weaner house before pigs were transported to site B. Variation among the numbers of experimental pigs at each site existed due to on-farm management practices. The experimental design is outlined in Table 3. The identification devices tested were as follows: 2 types of electronic identification ear tags that represent the 2 technologies of information exchange that are accepted by the International Standard Office (ISO) standard 11784 (ISO, 1996a) and 11785 (ISO, 1996b): (1) Allflex full duplex (FDX, lightweight button tag, 31-mm diam., 5.3 g, Allflex Australia, Brisbane, Australia, ISO 11784/11785, n = 198), (2) Leadertronic half duplex (HDX, triangular tag designed for cattle, 36 x 35 mm, 7.4 g, Leader Products, Melbourne, Australia, ISO 11784/11785, n = 204), (3) Leader Flexitag (conventional tag, nonelectronic, conventional, rectangular plastic ear tag, 48 x 54mm, 5.5 g, Leader Products, n = 196, Figure 1), and (4) Ketchum ear tattoo 101 (tattoo, kit number KR-1101-049, Ketchum Manufacturing Inc., Ontario, Canada, n = 190).
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), whereas the HDX and conventional tags were applied using the Leader Fast-tagger applicator (Leader, 2003). Ear tags were applied as close as practical to the base of the ear. The male buttons for HDX and conventional tags were applied on the inside of the ear of the pigs with the female half (RFID/visual tag) on the outside of the ear to assist visual readability and minimize facial irritation. Conversely, the male FDX tag was applied to the back (outside) of the ear due to placement of the tag numbers on the device. To apply the ear tattoo, the tattoo numbers were placed in the tattoo forceps, and the lever lock bar was closed to lock the numbers in place. With a toothbrush, a generous amount of Ketchum Animal Tattoo Ink -Green Paste (KI-1475-039) was applied to the tattoo pins. The tattoo applicator was positioned so the pins were on the outside of the ear. When the forceps were closed, care was taken to avoid excessive pressure as the ear was pierced. Ink was rubbed into the tattoo holes with thumb on inked surface against forefinger on the noninked surface of the ear.
One person applied all the identification devices, assisted by 2 people catching the pigs and 1 person setting up the devices and recording the data. For each pig sex, pen number, type of identification device, and the identification number placed in each ear were recorded. In addition to assessing the efficacy of each device, the application time for each pig (number of s taken to catch the pig, load the tagging-tattoo device, and apply the device) and the cost of materials were recorded.
Monitoring Visual Readability, Tag Retention, and Electronic Readability
All electronic tags were scanned before application using a handheld transceiver (EE-300–120; Allflex, 2002) to ensure they were functional. On-farm device performance, including visual readability at close range (less than 1 m with the pig restrained), readability of the electronic devices, and retention rate, was determined. According to the handheld recommendations, a reading distance of 10 cm for FDX plastic ear tags and a distance of 15 cm for HDX plastic ear tags were used to assess electronic failures (Allflex, 1999). Readings were taken on-farm at 8 wk after application for all animals and again at 14 and 17 wk after application for all pigs at site A and site B, respectively, before the first batch of pigs left the farm for slaughter.
When necessary, a damp cloth was used to clean the tags to assist in determining visual readability. Stock boards were used to herd individual pigs into the corner of a pen to scan tags and record adverse side effects and behavioral observations. To maintain handler safety, snares were used to restrain the pigs when they reached > 60 kg.
The Allflex Compact Reader was chosen to measure electronic readability due to its size and ease of use. Electronic readability was described as by Caja et al. (1999) and Babot et al. (2006) using the following: (transponders read at the control/transponders present at the control) x 100. Visual readability failure was the only component accounted for in determining overall tattoo readability, whereas overall conventional tag readability included tag loss and visual readability failures. The overall readability of FDX and HDX tags consisted of tag loss and electronic failure. Visual readability failure was not considered for electronic tags as the electronic capabilities of the tag were being assessed.
Monitoring Adverse Effects
Pigs were monitored at both sites at 0, 1, 3, 8, and 11 wk as well as before slaughter at site A at 14 wk and site B at 17 wk after application for adverse effects such as hematoma or edema at the tag site and skin allergies to the tattoo paste. Mortality was also recorded throughout the growing-finishing period to determine the number of fatalities related to device presence.
Statistical Analysis
Statistical analysis of data was conducted using STATA (version 8.2 2005, StataCorp LP, College Station, TX). To ascertain the extent of within-pig clustering of retention and readability in this data set, a separate multilevel logistic regression was constructed for each outcome, and the intracluster correlation coefficient was calculated (Dohoo et al., 2003). Because these coefficients (0.03 for retention, 0.04 for visual readability) indicated little clustering of tag loss or problems with tag readability within pig, we compared the level of significance of visual readability failure, tag retention rates, and electronic failure outcomes between identification device types at the 2 site locations using the Fisher exact test. The experimental unit was the ear of each pig, replicated by the number of pigs at each site, with separate logistic regression models constructed to assess the association among device retention, visual readability failure and electronic failure, with site location and device type. Odds ratios were calculated to further quantify associations (Kleinbaum and Klein, 2002; Dohoo et al., 2003) between identification device type and site (housing and pig management). The model used to determine visual readability failure was:
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where p = the probability of device retention, visual readability failure, or electronic failure with the model varying depending on the outcome being analyzed; K = the constant (reference site and identification device) and the variation factors; Si = the site type, which is the effect of site A compared with site B; Dj = the identification device, which is the effect of FDX, HDX, conventional tags, and tattoo compared with one another; and S x Dij = the interaction between identification device and site type. Sex of the animal and operator were not included in the model, because no differences were detected according to animal sex, and all device application was conducted by the same person, thereby eliminating operator variation.
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RESULTS AND DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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.
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In the Australian context, there are many small-scale, noncommercial producers in peri-urban and regional areas, particularly in the eastern states. Anecdotal evidence suggests these operations are low-tech with very little on-farm recording systems. Visual readability was considered an important factor in designing an effective traceability system for all pigs after farm-gate while providing a simple low-tech management tool for producers on-farm.
Tag Retention
Tag retention was excellent in the first 8 wk after application and did not differ among tagging devices (P > 0.05). No conventional tags were lost from the ears of pigs at either site during the first 8 wk after application. Minimal losses (less than 2%) have also been reported in other studies using conventional tags where pigs were housed intensively (Stärk et al., 1998; Caja et al., 2005; Babot et al., 2006). Tag retention (Table 4
) averaged 100% for FDX tags and 96.0% for HDX tags 8 wk after application. Previous research reported losses of electronic identification tags of 0% (Stärk et al., 1998), 2.3% (Babot et al., 2006), and 8.8% (Caja et al., 2005).
Tag loss increased after 8 wk after application and varied with housing system. Conventional tag loss was greater (P < 0.05) among pigs housed in concrete-based pens (29%) than in pigs housed on bedding (5%) in the 6- to 9-wk period before slaughter. More FDX tags were retained than HDX tags (P < 0.05), with losses of 1.6 and 14.9%, respectively. In general, retention of FDX tags was greater (P < 0.05) than other tag types in traditional pens. Retention of FDX and conventional tags was 3.3 and 4.3 times better (P < 0.05), respectively, than HDX tags in the deep litter system. Further logistic regression analysis showed that site location had no effect (P > 0.05) on visual readability, electronic readability, and adverse effects.
As observed in our results, Caja et al. (2005) indicated that most ear tag losses occurred during the last period of fattening (160 to 180 d; Caja et al., 2005). Studies by Schmolke et al. (2004) indicated that changes in social behavior of pigs became evident as they got heavier, suggesting an increased incidence of fighting when groups of pigs were mixed. These authors reported a significant portion of tag loss during the grower phase. In our experiment, high summer temperatures, fighting during regrouping, or both, may have affected pig behavior during the late growing period. In addition, the automated feeding system failed at site A, and pigs did not have ad libitum access to feed for a day during this period. This may have resulted in increased fighting and increased ear chewing and may have contributed to tag loss during this period.
Three previous studies identified tag design and manufacturing processes, such as increased weight and shape (dimension) of the ear tag to be related to electronic ear tag loss (Hasker et al., 1992; Caja et al., 2005; Babot et al., 2006). The HDX electronic tag, although originally designed for use in cattle, was approximately 2 g heavier than the other tag types studied, and this, together with the shape and the type of plastic used, may be unsuitable for manufacturing ear tags for pigs (Babot et al., 2006) and could provide insight to the poor retention of this particular HDX electronic device.
Electronic Readability
Full duplex tags maintained a 100% scanning rate throughout the study, whereas HDX tags varied between 99 and 90.8% at the 8 wk after application and before slaughter controls (Table 4). Of the HDX tags that showed readability problems, 4 devices failed to read at both data collection times, despite a positive before scan. A further 14 HDX tags failed to read at the before-slaughter data collection times.
Five functional HDX tags failed to read at 8 wk after application but read correctly at the before slaughter control. It is likely this reading failure was due to the transceiver that was used. A faulty transponder was the more likely cause. Reading failure could also have resulted from frequency interference with other nearby electronic devices. As identified by Caja et al. (2005) and Babot et al. (2006), the majority of failed electronic devices also showed signs of bite or friction marks; however, we were unable to determine whether this had any effect on electronic readability.
Because there was no third control, it is difficult to determine if reading failure at the before-slaughter control was a result of transceiver failure, electronic interference, or a broken transponder. Therefore, the 14 failed HDX tags at the before-slaughter control were considered as having transponder failures, with 9.2% HDX electronic failures detected overall at the end of the fattening period.
Electronic devices for use in pig identification are a recent introduction to Australia. Therefore, at the time of this study, electronic devices used for other species (such as the chosen HDX tag for cattle) were used to determine the effectiveness of various designs and technology that were and could be available for pigs. Differences between experiments and study sites may also be attributed to pig behavior (for example, pigs chewing tag devices leading to stretching of the ear at the tag site resulting in tag loss).
Overall Identification Device Readability
Overall readability for conventional tags varied from 65.4% in site A to 87.7% in site B with tag loss and visual readability failure considered. The final readability of the tattoo differed (P < 0.05) between sites and reached 40.0% in site A and 21.8% in site B. Overall readability values for electronic ear tag devices of 71.8% for HDX tags and 98.4% for FDX tags varied (P < 0.05) between the device types (Table 4). No differences were detected (P > 0.05) between sites for both FDX and HDX electronic ear tags. With tag loss and visual or electronic readability accounted for, FDX tags performed better (P < 0.05) than all other tag types in traditional pens and deep litter.
Production-Limiting Effects
Most adverse events occurred within the first 2 wk after application, with those observed before slaughter detected in conjunction with fighting lesions that may be associated with pigs being resorted at each growth stage in site A. Although no acute infections were observed after application, some tag sites appeared to take some time to heal (Table 5), with some scabbing and development of a small hematoma at the tag site. This was most common at site A, where hygiene varied between pens. Previous studies in New Zealand showed similar results where adverse tissue reaction to the tag site had evolved into tissue swelling, proliferation, tissue damage, and occasional bleeding (Stärk et al., 1998).
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Comparative Cost of Identification Devices
Identification device costs ranged from $0.05 for the tattoo to $2.39 for the HDX tags. No differences were observed in the time taken to apply electronic and conventional tags, which took 5.3 and 4.8 s to apply, respectively (Table 6). The overall costs per application were determined assuming a labor charge of $20/h. With application time and labor costs considered, the costs to apply electronic ear tags ranged from $2.25 for FDX tags to $2.42 for HDX ear tags and were similar to those reported by Saa et al. (2005). Although overall costs for the conventional tags were greater than that reported by Saa et al. (2005), it was considered to be relatively cost-effective when compared with electronic devices tested. Despite the lengthy duration to apply an ear tattoo, this device was the most cost-effective at $0.14/tattoo.
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), and when compared with the on-farm performance and the overall cost of applying the device, conventional tags were considered the most cost-effective nonelectronic identification device, followed by the FDX electronic device.
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). Additional benefits such as savings in the cost of eradicating endemic diseases, gains made from improved genetics, and carcass quality and premium prices for products, as well as improved consumer confidence through the ability to rapidly trace sources of disease or contamination, may eventually be developed (Geers et al., 1997; Disney et al., 2001).
Identification of weaner pigs from 4 wk of age had no apparent adverse effects on the pigs. Conventional tags were cost-effective in terms of device cost, application time, and visual readability; however, losses of up to 27.8% were observed. The International Committee for Animal Recording recommends a 98% retention rate (ICAR, 2005) for any identification device used for livestock. With this in mind, our results indicate the FDX electronic tag was the most efficient identification device in terms of retention rate, application ease, unfaltering scanning ability, and providing the best overall readability throughout the growth period. Based on on-farm performance, the FDX electronic tag was the most effective device for identifying live weaner pigs in a commercial operation in Australia from birth to slaughter; however, device cost could be a limiting factor in the use of this technology in the pork industry.
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Footnotes |
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2 We would like to thank the assistance of Windridge Farms, New South Wales, Australia, for the use of their facilities to undertake this study.
3 Corresponding author: nicoles{at}camden.usyd.edu.au
Received for publication March 14, 2007. Accepted for publication July 19, 2007.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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