An investigation of micronutrient supplementation in weaner lambs to improve growth rates in southeast Australia

OBJECTIVE

A producer survey by questionnaire assessed supplements used in sheep and reasons for use. This was followed by field trials on eight sheep properties in SE NSW to determine the effect of commonly used commercially available supplements on growth rates of Merino and crossbred lambs.

DESIGN

On each property, 450 lambs were selected at weaning and randomly allocated to nine groups of 50 sheep (eight treatment and a control group). Supplements were applied as per manufacturer's recommendation every 6-12 weeks. At each application, all sheep were weighed and data on general flock health and management were collected.

RESULTS

All but one of the survey respondents (n = 77) had used supplements in their sheep at some stage. The reasons for use were most commonly for general health and production benefits (n = 21; 26.9%) and to prevent or treat specific diseases/deficiencies (n = 7; 9.0%). The average daily weight gains (ADWG) of the lambs over the trial period varied from 0.074 kg to 0.213 kg/head/day. Statistical analysis showed that overall there was not a significant difference (P = 0.587) between ADWG among lambs that received supplements and lambs that did not.

CONCLUSION

Results of this study show that application of supplements were not linked to improved growth rates in clinically normal crossbred and Merino lambs under the trial farm conditions between weaning and 15 months of age. Effects of supplements on health and production in adult sheep and how supplement response can be best measured in sheep flocks (especially in relation to health and welfare) and linked to productivity requires further investigation.

The importance of understanding end user acceptability of new technology to support animal health management

This pilot study investigates the acceptability of a mobile application (app) developed to assist livestock producers make better animal health decisions with the support of a local veterinarian. With the increase in new technologies available for producers, acceptability evaluation is important to ensure that technology is designed considering end users' needs. An acceptability qualitative study, using semi-structured interviews, was designed including a purposive selection of sheep producers and livestock veterinarians. Eleven producers and six veterinarians participated in the study. Results suggest that producers would use such a tool to contact private veterinarians in non-emergency situations to obtain animal health advice. From veterinarians' perspective, while features of the app, such as messaging and notifications, were considered useful, concerns were raised about its capacity to enhance business opportunities and potential privacy implications. This study highlights the importance of engaging with end users in the early stages of the design and the introduction of new technology to maximise potential for adoption.

Transmission of highly virulent community-associated MRSA ST93 and livestock-associated MRSA ST398 between humans and pigs in Australia

Pigs have been recognised as a reservoir of livestock associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in Europe, Asia and North America. However, little is known about the presence and distribution of MRSA in the Australian pig population and pig industry. This study describes the presence, distribution and molecular characteristics of the human adapted Australian CA-MRSA ST93 isolated from pigs, people, and the environment within a piggery. Isolates were subjected to antibiotic susceptibility testing, DNA microarray, whole genome sequencing, multi locus sequence typing, virulence and resistance gene characterization and phylogenetic analysis. MRSA were isolated from 60% (n = 52) of farm workers where 84% of isolates returned ST93 and the rest ST398. Of the thirty-one pig isolates tested further, an equal number of ST398 and ST93 (15 each) and one as ST30-V were identified. Four of six environmental isolates were identified as ST93 and two as ST398. This study has identified for the first time in Australia the occurrence of CA-MRSA ST93 and LA-MRSA ST398 amongst farm workers, pigs, and the farm environment. Comparative genome analysis indicates that ST398 is likely to have been introduced into Australia from Europe or North America. This study also reports the first linezolid resistant MRSA isolated in Australia.

Point of truth calibration for disease prioritisation-A case study of prioritisation of exotic diseases for the pig industry in Australia

The objective of this study was to trial point of truth calibration (POTCal) as a novel method for disease prioritisation. To illustrate the application of this method, we used a previously described case-study of prioritisation of exotic diseases for the pig industry in Australia. Disease scenarios were constructed from criteria which described potential impact and pig-producers were asked to score the importance of each scenario. POTCal was used to model participants' estimates of disease importance as a function of the criteria, to derive a predictive model to prioritise a range of exotic diseases. The best validation of producers' estimates was achieved using a model derived from all responses. The highest weighted criteria were attack rate, case fatality rate and market loss, and the highest priority diseases were the vesicular diseases followed by swine fevers and zoonotic encephalitides. Comparison of results with a previous study in which probabilistic inversion was used to prioritise diseases for the same group of producers highlighted differences between disease prioritisation methods. Overall, this study demonstrated that POTCal can be used for disease prioritisation. An advantage of POTCal is that valid models can be developed that reflect decision-makers' heuristics. Specifically, this evaluation of the use of POTCal in animal health illustrates how the judgements of participants can be incorporated into a decision-making process. Further research is needed to investigate the influence of scenarios presented to participants during POTCal evaluations, and the robustness of this approach applied to different disease issues (e.g. exotic versus endemic) and production types (e.g. intensive versus extensive). To our knowledge, this is the first report of the use of POTCal for disease prioritisation.

Investigating risk factors and possible infectious aetiologies of mummified fetuses on a large piggery in Australia

OBJECTIVE

To investigate risk factors and potential infectious aetiologies of an increased mummification rate (>2%) identified over time on a 1200-sow farrow-to-finish farm in Australia.

METHODS

Association of potential non-infectious risk factors and the mummification rate was investigated using 15 years of breeding herd data (40,940 litters) and logistic regression analysis. Samples from a limited number of mummified fetuses were taken to identify potential infectious aetiologies (porcine parvovirus, Leptospira pomona, porcine circovirus type 2, Bungowannah virus and enterovirus).

RESULTS

Logistic regression analysis suggested that the mummification rate was significantly associated with sow breed and parity, year and total born and stillborn piglets per litter. The mummification rate was lower (P < 0.001) in Landrace (3.4%) and Large White (2.6%) sows than in Duroc sows (4.9%). Gilts (2.9%) had a lower (P < 0.001) mummification rate than older sows. The mummification rate increased with total born litter size and decreased with the number of stillborn piglets (P < 0.001). A clustering effect within individual sows was identified, indicating that some sows with mummified fetuses in a litter were more likely to have repeated mummifications in subsequent litters. No infectious agents were identified in the samples taken.

CONCLUSION

Results from this study suggest that the increased mummification rate identified over time on this farm is likely to be a non-infectious multifactorial problem predisposing the occurrence of mummification. Further research is required to better understand the pathophysiology of mummification and the role that different non-infectious factors play in the occurrence of mummified fetuses.

Identifying and measuring stakeholder preferences for disease prioritisation: A case study of the pig industry in Australia

We describe stakeholder preference modelling using a combination of new and recently developed techniques to elicit criterion weights to incorporate into a multi-criteria decision analysis framework to prioritise exotic diseases for the pig industry in Australia. Australian pig producers were requested to rank disease scenarios comprising nine criteria in an online questionnaire. Parallel coordinate plots were used to visualise stakeholder preferences, which aided identification of two diverse groups of stakeholders - one group prioritised diseases with impacts on livestock, and the other group placed more importance on diseases with zoonotic impacts. Probabilistic inversion was used to derive weights for the criteria to reflect the values of each of these groups, modelling their choice using a weighted sum value function. Validation of weights against stakeholders' rankings for scenarios based on real diseases showed that the elicited criterion weights for the group who prioritised diseases with livestock impacts were a good reflection of their values, indicating that the producers were able to consistently infer impacts from the disease information in the scenarios presented to them. The highest weighted criteria for this group were attack rate and length of clinical disease in pigs, and market loss to the pig industry. The values of the stakeholders who prioritised zoonotic diseases were less well reflected by validation, indicating either that the criteria were inadequate to consistently describe zoonotic impacts, the weighted sum model did not describe stakeholder choice, or that preference modelling for zoonotic diseases should be undertaken separately from livestock diseases. Limitations of this study included sampling bias, as the group participating were not necessarily representative of all pig producers in Australia, and response bias within this group. The method used to elicit criterion weights in this study ensured value trade-offs between a range of potential impacts, and that the weights were implicitly related to the scale of measurement of disease criteria. Validation of the results of the criterion weights against real diseases - a step rarely used in MCDA - added scientific rigour to the process. The study demonstrated that these are useful techniques for elicitation of criterion weights for disease prioritisation by stakeholders who are not disease experts. Preference modelling for zoonotic diseases needs further characterisation in this context.

Building a picture: Prioritisation of exotic diseases for the pig industry in Australia using multi-criteria decision analysis

Diseases that are exotic to the pig industry in Australia were prioritised using a multi-criteria decision analysis framework that incorporated weights of importance for a range of criteria important to industry stakeholders. Measurements were collected for each disease for nine criteria that described potential disease impacts. A total score was calculated for each disease using a weighted sum value function that aggregated the nine disease criterion measurements and weights of importance for the criteria that were previously elicited from two groups of industry stakeholders. One stakeholder group placed most value on the impacts of disease on livestock, and one group placed more value on the zoonotic impacts of diseases. Prioritisation lists ordered by disease score were produced for both of these groups. Vesicular diseases were found to have the highest priority for the group valuing disease impacts on livestock, followed by acute forms of African and classical swine fever, then highly pathogenic porcine reproductive and respiratory syndrome. The group who valued zoonotic disease impacts prioritised rabies, followed by Japanese encephalitis, Eastern equine encephalitis and Nipah virus, interspersed with vesicular diseases. The multi-criteria framework used in this study systematically prioritised diseases using a multi-attribute theory based technique that provided transparency and repeatability in the process. Flexibility of the framework was demonstrated by aggregating the criterion weights from more than one stakeholder group with the disease measurements for the criteria. This technique allowed industry stakeholders to be active in resource allocation for their industry without the need to be disease experts. We believe it is the first prioritisation of livestock diseases using values provided by industry stakeholders. The prioritisation lists will be used by industry stakeholders to identify diseases for further risk analysis and disease spread modelling to understand biosecurity risks to this industry.

Use of stakeholder analysis to inform risk communication and extension strategies for improved biosecurity amongst small-scale pig producers

Extension and communication needs amongst small-scale pig producers, described as pig producers with less than 100 sows, have been previously identified. These producers, who are believed to pose a biosecurity risk to commercial livestock industries, are characterized by a lack of formal networks, mistrust of authorities, poor disease reporting behaviour and motivational diversity, and reliance on other producers, veterinarians and family for pig health and production advice. This paper applies stakeholder identification and analysis tools to determine stakeholders' influence and interest on pig producers' practices. Findings can inform a risk communication process and the development of an extension framework to increase producers' engagement with industry and their compliance with biosecurity standards and legislation in Australia. The process included identification of stakeholders, their issues of concerns regarding small-scale pig producers and biosecurity and their influence and interest in each of these issues. This exercise identified the capacity of different stakeholders to influence the outcomes for each issue and assessed their success or failure to do so. The disconnection identified between the level of interest and influence suggests that government and industry need to work with the small-scale pig producers and with those who have the capacity to influence them. Successful biosecurity risk management will depend on shared responsibility and building trust amongst stakeholders. Flow-on effects may include legitimating the importance of reporting and compliance systems and the co-management of risk. Compliance of small-scale pig producers with biosecurity industry standards and legislation will reduce the risks of entry and spread of exotic diseases in Australia.

Assessment of current disease surveillance activities for pigs post-farmgate in New South Wales

OBJECTIVES

Evaluate current disease surveillance activities at saleyards and abattoirs in New South Wales (NSW) in order to establish the prevalence of clinical anomalies in pigs at different sites and to compare the sensitivity of detecting anomalies inside versus outside of pens.

PROCEDURE

Routine inspections of pigs by staff and government inspectors were observed at two saleyards and two abattoirs in NSW during three visits over a 2-month period (January 2008-March 2008). All pigs presented for sale or slaughter were examined for 19 clinical anomalies from either the side of the pen or while animals were moving outside the pen, with data being combined to give an assumed 'gold standard'. We compared the prevalence of anomalies among animals at the four sites using logistic regression, as well as the sensitivity of detection of the two inspection methods.

RESULTS

Frequency and methodology of routine inspection varied among sites. Of the 7747 pigs inspected, 822 (10.6%) showed at least one clinical anomaly. There was moderate agreement between detecting anomalies in penned pigs versus while being moved. Pigs at one abattoir exhibited significantly fewer anomalies than pigs at the other sites.

CONCLUSION

The prevalence of anomalies among pigs at saleyards and abattoirs in NSW was relatively high ( approximately 10%). Weaknesses in current disease surveillance activities for pigs post-farmgate have been identified. Increased regulation, surveillance training and modification of standard operational procedures for inspection have the potential to improve the current system.

A qualitative study of the management and biosecurity practices of 13 interviewed pig owners selling via informal means in New South Wales, Australia

There is increasing interest in the trading practices of producers who market pigs at live auction in Australia and the potential for infectious disease establishment and spread. The practices that underpin the commercial pork industry in Australia are well known. However, little is known about informal movements of pigs in Australia, and the biosecurity risks associated with pig production enterprises that utilise these methods of trade. The aim of this study was to qualitatively evaluate the biosecurity and pig-keeping practices of owners who trade pigs informally for Foot and Mouth Disease and Classical Swine Fever exposure and spread. Interviews were conducted with 13 pig owners who trade via informal means between April and June 2009. Information provided by producers was able to be validated for the six interviews conducted on-farm. There was limited application of recommended biosecurity practices on-farm and few kept health and management records. All interviewees reared other livestock species, such as ruminants and/or poultry, as well as pigs. Most interviewed owners claimed to quarantine introduced pigs from the main herd; however, few complied with industry recommendations. The results of this study suggest that pig owners (n = 13 interviewed) who currently trade their pigs informally pose few threats for the introduction of emergency animal disease. Pig keepers largely obtained their pig feed from reputable sources and appeared to have a sound understanding of swill feeding. However, the lack of on-farm biosecurity, variable quarantine practices and the failure to keep health records could play a role in the spread of an emergency animal disease if it was to be introduced. Further work is being undertaken to determine, qualitatively, the risk associated with the management practices undertaken by informal pig traders and Foot and Mouth Disease and Classical Swine Fever introduction and spread.

Lifetime traceability of weaner pigs in concrete-based and deep-litter production systems in Australia1,2

A field study was conducted on a 2,300-sow piggery in southwestern New South Wales, Australia, over a 17-wk period (from weaning at 4 wk of age) to assess the suitability for lifetime traceability of weaners of 4 identification devices: 1) full duplex ear tag (FDX, Allflex), 2) half duplex ear tag designed for cattle (HDX, Leadertronic), 3) conventional ear tag (Leader), and 4) ear tattoo (Ketchum ear tattoo 101). Visual readability, retention rate, electronic failures, and adverse side effects were assessed at 8 wk after application at both sites and before slaughter at 14 or 17 wk after application at site A and site B, respectively. A total of 394 weaner pigs were randomly assigned after weaning to 6 treatment groups and reared either in small groups in intensive, indoor, concrete-based pens (n = 224; site A) or in a large group on deep litter (n = 170; site B). Visual readability was similar for all ear tag types before slaughter (P > 0.05); however, visual readability of the ear tattoo was lower (P < 0.05), with between 78.2 and 60.0% illegible due to ink fading. Few tags were lost in the 8-wk period after application; however, tag loss increased for each tag device after this period and varied with housing system. Conventional tag loss was greater among pigs housed at site A (29.0%) than in pigs housed at site B (4.9%) in the 6- to 9-wk period before slaughter. The overall readability of FDX and HDX tags did not differ (P > 0.05) between sites; however, overall readability of FDX tags at 98.4% was better (P < 0.05) than 71.8% for HDX tags. Tag costs ranged from $0.73 for the conventional ear tag to $2.42 for the HDX ear tag. The identification devices did not induce production-limiting adverse effects after they were applied. Under conditions of this study, FDX electronic ear tags were the most efficacious for lifetime identification of weaner pigs on-farm.

Traceability of extensively produced Iberian pigs using visual and electronic identification devices from farm to slaughter

A total of 351 Iberian pigs with equal numbers of both sexes from 2 commercial farms were used to study the ability of various identification devices to guarantee the traceability required for labeled meat products from Iberian pigs reared under extensive production conditions in Spain. The performance of tattoos, visual ear tags, electronic ear tags, and i.p.-injected transponders of half duplex and full duplex technologies were compared during a production cycle from nursery to slaughter at 15 mo of age (156 +/- 3 kg of BW). No major health reactions to any of the identification methods were detected. Results showed that tattooing was not an adequate identification procedure due to reading difficulties as a consequence of dark skin, soiled appearance, and figure deformation. Ear tag losses and failures were affected by fencing type and increased in one of the farms (20.4 and 15.7% for losses and failures, respectively; P < 0.05) as a consequence of using barbed-wire fences. Ear tag losses decreased when fences changed to stone blocks at 365 d of age. Visual and electronic ear tag losses during transport and slaughter were low (3.7% for visual and 3.1% for electronic tag). Results of injectable transponders during the growing-fattening period were variable and were more readable for the half duplex than for the full duplex i.p. transponders (92.0 vs. 68.7% +/- 1.5; P < 0.05). Handheld transceivers worked properly under extensive conditions, although the body size and skin characteristics of the Iberian breed might limit the performance of reading devices, and the use of transceivers with longer reading distances is recommended. The main problem observed with i.p. transponders was their low recovery rate at slaughter due to the lack of adherence of the transponders to the omentum.

Comparison of visual and electronic identification devices in pigs: slaughterhouse performance

Traceability during slaughter was studied in 1,581 pigs identified by different devices. Treatments were visual ear tags (n = 1,300), electronic ear tags of different technologies (half-duplex, n = 636; full-duplex, n = 632), and intraperitoneally injected transponders of different technologies (half-duplex 32 mm, n = 645; full-duplex 34 mm, n = 642). Piglets were individually identified at weaning and intensively fed until 100 kg of BW. Pigs were slaughtered in 2 commercial slaughterhouses (including scalding, flaming, and peeling) at different throughputs (450 and 550 pigs/h). Readability during slaughtering was checked visually and using standardized hand-held transceivers. No effect of slaughterhouse was detected (P > 0.05). Ear tag losses in the slaughtering line were similar for visual (3.7%) and half-duplex (3.5%) but were increased for full-duplex (11.5%; P < 0.05). Moreover, electronic failures during slaughtering did not differ (P > 0.05) between ear tags (half-duplex, 1.1%; full-duplex, 0.6%). Intraperitoneally injected transponders were not affected by slaughtering (retention 100%, no failures), and 89.0% of the transponders were manually recovered from the abdominal viscera in the offal trays. The remaining transponders (11.0%) were lost on the floor, but none were found in the carcasses. No differences (P > 0.05) in recovery were observed between intraperitoneal transponders. Considering on-farm and slaughterhouse data, total traceability from farm to carcass release was greater (P < 0.05) for intraperitoneally injected transponders (98.2%) than for ear tags. Between ear tags, the greatest traceability was obtained with visual tags (95.7%), which differed (P < 0.05) from electronic tags (half-duplex, 91.4%; full-duplex, 84.5%; P < 0.05). Intraperitoneally injected transponders were an efficient and reliable identification system for tracing pigs from farm to the end of the slaughter line, allowing the transfer of pig identification to the carcass. Adherence of intraperitoneally injected transponders to the viscera should be improved to reduce risks of loss in the meat chain. A dual system based on intraperitoneally injected transponders and plastic ear tags would allow a redundant and automatic reading system that is efficient and reliable for data management and traceability in the swine industry.

Suitability of electronic mini-boluses for early identification of lambs

Three types of ceramic mini-boluses, B1 [13.8 g; 10.5 x 51.0 mm (o.d. x length)], B2 (16.2 g; 12.2 x 42.2 mm), and B3 (20.1 g; 11.2 x 56.4 mm), were used to electronically identify as soon as possible after birth a total of 545 lambs of 3 breeds: Ripollesa (meat breed, n = 274), Manchega (dairy breed, n = 129), and Lacaune (dairy breed, n = 142). Boluses were administered by a trained operator using a balling gun or directly by hand. Lambs were also identified with 2 types of plastic ear tags in the left (temporary, 1.5 g) and the right (permanent, 4.1 g) ears. Lamb and identification device performances were checked during suckling (to wk 5 or 7) and fattening. At 24 kg of BW, lambs were slaughtered (n = 385) or kept for breeding (n = 144). No differences in performance were observed between the 2 dairy breeds, and their data were pooled. Minimum BW for bolus administration was lower in dairy than in meat lambs (P < 0.001). Across breeds, B1 and B3 did not differ in lamb age (27 d) and weight (9.2 kg) at administration, but B2 required older and heavier lambs (33 d and 11.1 kg; P < 0.01). Boluses did not affect lamb performance, but final readability at slaughter differed between B1 and B2 (97.7 and 95.2%, respectively) and B3 (100%), and between ear tags (temporary, 98.1; permanent, 100%). Bolus recovery was 100% in all cases, but the proportion of boluses found in the reticulum varied among bolus type (83.3 to 93.8%; P < 0.05). Three B1 (2%) were recovered from the abomasum. In a second experiment, effects of the intermediate mini-bolus (B2) on diet digestibility were evaluated. Digestibility of control and bolus-administered, Manchega ram lambs (14.9 kg of BW; n = 8) fed ad libitum with 2 pelleted concentrates and barley straw was assessed in digestibility crates. Feed intake and nutrient digestibility were measured in four 21-d periods, during which lambs received the 2 diets consecutively. No differences in intake, growth performance, or nutrient digestibility were observed between control and bolused lambs. In conclusion, the B3 mini-bolus proved to be an efficient device for identification of lambs before weaning (recommended age, >4 wk; recommended BW, >10 kg), allowing a reliable traceability of dairy and meat lambs until slaughter.

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

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.

Comparison of visual and electronic identification devices in pigs: On-farm performances1,2

A total of 1,822 pigs from 2 farms (farm A, n = 1,032; farm B, n = 790) were used to evaluate pig traceability under on-farm conditions by using identification devices (n = 4,434) of different technologies. The devices were visual ear tags (n = 1,533; Model 1, n = 776; Model 2, n = 757), electronic ear tags (n = 1,446; half-duplex, n = 702; full-duplex, n = 744), and intraperitoneally injected transponders (n = 1,455; half-duplex, n = 732; full-duplex, n = 723). A group of 790 pigs wore 3 types of devices, and 1,032 wore 2 devices. Piglets were identified before (wk 1 to 3 of age; farm A) or after (wk 3 to 4 of age; farm B) weaning and intensively fattened until approximately 100 kg of BW. Readability of devices was checked at each farm operation by using standardized handheld transceivers. No negative effects of the identification devices on animal health (mortality rate, 8.4%) or performance were detected. On-farm losses averaged 1.6% for ear tags (visual, 0.8%; half-duplex, 1.9%; full-duplex, 2.7%; P > 0.05) and 1.8% for intraperitoneally injected transponders (half-duplex, 1.7%; full-duplex, 1.9%; P > 0.05). Moreover, 1.4% electronic failures occurred in the electronic ear tags (half-duplex, 2.2%; full-duplex, 0.6%; P < 0.05) but not in the intraperitoneally injected transponders. Final on-farm readability was greater (P < 0.05) for visual ear tags (99.2%) than for electronic ear tags (half-duplex, 95.9%; full-duplex, 96.7%; P > 0.05). Readability for intraperitoneally injected transponders was intermediate (half-duplex, 98.3%; full-duplex, 98.1%; P > 0.05). Electronic devices were in all cases easier and faster to read than the visual ear tags. Visual ear tags and intraperitoneally injected transponders were efficiently retained under conditions of commercial pig farms, which agrees with the minimum values recommended by the International Committee for Animal Recording (> 98%). When readability and reading ease were also included as decision criteria, injectable transponders were preferred.

Evaluation of the retention of electronic identification boluses in the forestomachs of cattle

A total of 1,203 beef calves were used to evaluate 2 series of electronic identification boluses. Calves were intensively fattened and slaughtered at approximately 1 yr of age. Series 1 (n = 576 calves) consisted of 10 types of boluses with the same external dimensions (o.d. x length: 21 x 68 mm) but varying in weight (11 to 75 g) and specific gravity (0.63 to 3.36). Six boluses were made of ceramic (5 prototypes and 1 commercial bolus) and 4 were tubes made of plastic filled with concrete. Series 2 (n = 627 calves) consisted of 3 prototypes and 5 commercial boluses of different ceramic materials varying in external dimensions (o.d.: 15 to 21 mm; length: 39 to 78 mm), weight (20 to 73 g), and specific gravity (3.00 to 3.87). Boluses were administered to milk-fed calves (2 to 5 wk of age) by using adapted balling guns. To determine the anatomical limit for a bolus passing through the gastrointestinal tract, the size of the reticuloomasal orifice was measured in 90 male and 62 female fattened calves at slaughter. Three calves in series 1 (0.3%) could not swallow the 21-mm (o.d.) bolus at the first attempt and received the bolus 1 wk later. No problems for early administration were found with thinner boluses (o.d. < 20 mm) in series 2, and no signs of disease or growth alteration were detected in any bolused calves. Retention rate until slaughter varied according to bolus features and ranged from 0 to 100% (series 1), and from 69.7 to 100% (series 2). Inadequately dimensioned boluses were regurgitated or passed through the gastrointestinal tract and were excreted with the feces. The diameter of the reticuloomasal orifice differed between male and female yearling calves (32.5 and 29.9 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 = 0.99, P < 0.001), in which the minimum bolus weight estimated to reach a 99.5% retention rate was 61 g when volume and specific gravity were 22.4 mL and 2.72, respectively. To achieve an effective retention rate of electronic identification boluses in the forestomachs of fattening calves, bolus volume and specific gravity, in addition to weight, should be optimized. No boluses of specific gravity lower than 3.0 and thicker than 20 mm o.d. are recommended for identification of cattle from early rearing (< 20 d of age) to slaughtering.

Use of ear tags and injectable transponders for the identification and traceability of pigs from birth to the end of the slaughter line1,2

A total of 557 newborn piglets were used to compare eight identification devices, including one plastic ear tag as a control (C, n = 348) and two types of electronic ear tags (E1, n = 106; and E2, n = 103), and five types of injectable transponders (n = 557): small 12-mm (D12, n = 116; and S12, n = 110), medium 23-mm (T23, n = 108), and large (32-mm, T32, n = 115; and 34-mm, S34, n = 108). Injections were made s.c. in the auricle base (n = 248) and intraperitoneally (n = 309) using a new technique. All piglets were identified with two devices, but using electronic ear tags in conjunction with injection in the auricle was avoided on the same pig. Readability of devices was checked during fattening (until 110 kg BW) and slaughtering. On-farm losses were lower for control than for electronic ear tags (C = 1.1%; E1 = 8.8%; and E2 = 44.9%; P < 0.01); the latter also suffered electronic failures (E1 = 5.5%; and E2 = 55.1%; P < 0.001). On-farm losses of transponders injected in the auricle base were greater in large (S34 = 72.5%; and T32 = 46.3%; P < 0.05) than in small transponders (S12 = 19.4%; and D12 = 17.1%), but T23 (29.8%) only differed from S34. Transponder size did not affect on-farm losses for intraperitoneal injections in which only one loss was recorded (0.4%). All ear tags had similar losses during transportation to the slaughterhouse (1.2%), but no losses were observed in injectables. Slaughtering losses did not differ between ear tags (C = 11.2%; and E1 = 6.4%), but apart from losses, 12.8% of E1 failed electronically. Injection site affected losses and breakages during slaughtering (auricle base = 6.4%; and intraperitoneal = 0%), but recovery time did not significantly differ (auricle base = 28.6 s; and intraperitoneal = 18.9 s). Transponders in the auricle base were recovered by sight (30.2%), palpation (27.4%), or by cutting (42.5%). Intraperitoneal transponders were mainly recovered loose in the abdominal cavity (81.4%), whereas 18.6% fell on the floor. As a result, traceability varied significantly (P < 0.05) between control (86.7%) and electronic ear tags (0 to 68.1%) and injectable transponders, with the auricle base (17.8 to 75.0%) having lower values than intraperitoneal (98 to 100%). Intraperitoneal injection was a very effective tool for piglet identification and traceability, ensuring the transfer of information from farm to slaughterhouse. To warrant the use of this technique in practice, transponder recovery requires further investigation.