Electronic Identification in Traceable Systems

by 5m Editor
9 May 2008, at 12:00am

As pork chains become more diverse and with increased stringency of some export specifications, animal identification (ID) and traceability is a key component regarding assurance of customer specifications for livestock products, writes Ronald O. Bates, State Swine Specialist at Michigan State University.


Furthermore as more and more pork production chains gravitate to scripted management programs, which ensure unique conception to consumption practices, the ability to guarantee that each animal marketed was managed and treated as asserted is paramount for the success of these programs. Documentation of declared management and health treatment protocols is becoming the preferred way to certify that the stated management methods were those that were actually performed.

Animal Identification

Over the years many different methods have been used to identify pigs. Traditionally, pigs have been ear notched using the Universal Ear Notching system. In addition visual identification tags, typically ear tags, have been commonly used. These two methods have been used extensively in many different ways to identify pigs within and across production systems. Over the last decade there has been an increasing interest in using electronic identification (e-ID) to identify groups of animals as well as individual animals.

Most e-ID systems are passive systems that require the e-ID placed on or in an animal. The e-ID devise must pass through an antenna field to energize the e-ID device and allow a unique identification number or code to be transmitted to a reader. One of the main reasons that e-ID has come to the forefront of animal ID systems is the ability to capture the electronically transmitted number or code into an electronic database. When electronically transmitted, the identification number can be used to tie present and past histories of that animal together quickly, and it can be used in management applications such as feeding or sorting. As an example, when treating animals an animal that has just been treated can be identified by an e-ID reader that is tied to an electronic database for data recording purposes. The treatment given can also be recorded electronically and all information can be merged into a historical database. This can eliminate many paper and pencil activities, reduce misidentification of animals as well as provide database queries regarding management histories on animals in a convenient manner within the barns of a production system.

The two major questions regarding the implementation of e-ID typically revolve around reliability and affordability. The e-ID devises have become much more affordable in recent times and continue to decline in price. Reliability though is a multi-pronged issue. For an identification system to be reliable, it must be easily readable, not fail for an extended period of time, and it must remain on or in the animal. Regarding e-ID, the International Committee for Animal Recordings states that for e-ID to be considered for official ID systems it should have a retention rate of or greater than 98% (ICAR, 2005).

Concerning traceability for export or scripted production systems, documentation of animal management and health treatment is critical to assure end product users that the purchased product was raised to the specifications stated. The potential to trace the pork in a box or package back through the harvest facility and to the farm on which the animal was raised is feasible with the ability of passing animal identification across databases. In fact there are pork chains around the world that are presently doing this to some degree.

Yet questions still remain concerning the reliability of e-Id. Recently there were two reports published that compared visual identification systems (visual ear tags) with different e-ID systems. These reports were companion manuscripts that evaluated visual ear tag ID and compared it with e-ID that was either placed behind a visual ear tag or was an implanted e-ID bolus placed into the peritoneal cavity (stomach and intestine area). These studies were conducted on two different farms in Spain and included 4,434 pigs across both farms. Pigs were individually identified within the first three weeks after birth and followed through the harvest process (Babot et al., 2006; Santamarina et al., 2007). Regarding e-ID both half-duplex and full-duplex e-ID technology were included in the study. Half-duplex e-ID must send and receive its signal sequentially while full-duplex technology allows for its signal to be sent and received simultaneously. The implanted e-ID bolus was injected into the abdominal cavity between the intestines. Pigs were laid on their back and the injection site was cleaned with iodine. The injection site was .4 inches from the pig’s left of the midline and .8 inches below the navel. Injection of the e-ID bolus into the abdominal cavity took approximately 1 minute per pig.

Figure 1. Readability Rate of Identification Systems in Growing Pigs

Adapted from Babot et al., 2006

Pig performance and mortality rates were similar across ID types. Readability rates did differ between different ID systems (Figure 1). Readability included both retention of the ID as well as functionality of the ID. Pigs that had visual ear tag ID or the implanted e-ID bolus had similar readability rates at the time of marketing. This included the time from ID placement on or in the pig until the time pigs were marketed at approximately 220 lb. However, pigs with e-ID placed on an ear tag had lower readability rates. For the 3.7% of the ear tag e-ID that could not be read, 61.7% of the non-readers were due to loss of the e-ID devise from the ear tag. The remaining 38.3% of the non-readers, did remain on the ear tag but had lost functionality and could not be read at the time of marketing. It appears that an e-ID devise placed on an ear tag as the back of a tag can have a greater non-readability rate than standard ear tags. Implanted e-ID within the abdominal cavity was similar in functionality rate to visual ID.

At the end of the finish phase, pigs were marketed to one of two harvest facilities with line speeds of 400-600 carcasses per hour. After exsanguination, carcasses were scalded, dehaired and then moved through a flame chamber to remove all remaining hair. Each ID system was read after the carcass was moved through the flame chamber and before evisceration. Readability rates were highest for pigs with implanted e-ID and lowest for e-ID on ear tags (Figure 2). Visual ID systems were intermediate.

There was a significant difference in readability rates between the two ear tag e-ID systems. Carcasses with the half-duplex ear tag e-ID had a readability rate of 91.4% while pigs with the full-duplex ear tag e-ID had a readability rate of 84.5%. It was not apparent as to why this difference occurred. The half-duplex and full-duplex e-ID devises, were of the same size, shape, dimension and weight.

Recovery of the implanted e-ID bolus from the viscera tray after evisceration, across the two harvest facilities ranged from 85.5 to 90.8%. The remaining boluses fell from the carcasses during evisceration and were lost on the harvest facility floor. None of the e-ID boluses were found within the carcasses after evisceration. Within this study there was no risk of the e-ID bolus passing through the food chain in pork products.

Figure 2. Readability Rate of Identification Systems in Pigs through Harvest

Adapted from Santamarina et al., 2007

This study demonstrated that different ID systems could be used within verified production systems and the ID can remain functional for a majority of the pigs initially identified. However there were differences across identification systems. The greatest percentage of pigs which were initially identified and individually tracked through the evisceration phase of harvest was those implanted with e-ID boluses. The nearly perfect traceability rate met the standards proposed by the International Committee for Animal Recordings. Therefore in those countries in which this standard is required for scripted production systems or export specifications, this method of ID can be considered for use.

The study also demonstrated that tracking 100% of animals through a production system and harvest facility is very difficult. This becomes further complicated if production and management information is to be matched with individual carcasses so to verify 100% of carcasses were from pigs which matched the scripted management system for particular pork chains. Pork chains that choose to move information from the production system through the harvest facility to the end user will have to plan carefully which ID systems will best fit their consumer specifications and what degree of traceability is acceptable.

Literature Cited

Babot, D., M. Hernandez-Jover, C. Caja, C. Santamarina and J,J, Ghirardi. 2006. Comparison of visual and electronic identification devices in pigs: On-farm performances. J. Anim. Sci. 84:2575-2581.

ICAR. 2005. International Agreement of Recording Practices. Guidelines approved by the General Assembly held in Sousse, Tunisia, June 2004. International Committee for Animal Recording, Rome, Italy.

Santamarina, C., M. Hernandez-Jover, D. Babot, and C. Caja. 2007. Comparison of visual and electronic identification devices in pigs: Slaughterhouse performance. J. Anim. Sci. 85:497-502.


Published in MSU Pork Quarterly Vol 12 No 4 2007.

April 2008