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Methods to monitor pig classification and maintain the accuracy

This EUPIGCLASS project has been performed to:

The content of lean meat is the most essential characteristic of pig carcasses and it forms the common basis for payment to the pig producers and in markets after slaughter in all countries in EU. The aim of classification is to get an estimate of the content of lean meat. This estimation is performed by means of different types of instruments, characterized by different precision and technology. For the future development of pig carcass classification a European project (EUPIGCLASS) has been performed. 

Develop improved statistical procedures and assess new technology for the calibration, testing and control of pig carcass classification in order to achieve high level of standardization in all EU member states. The Quality Assurance Program will be one means to maintain performance and accuracy of classification.


The project has been organized in three work packages and the objectives have been

Image 1: The aim of classification is to get an estimate

of lean meat content. This photo shows the tissue proportions in a dissected ham.

Document and evaluate the present reference method for lean meat and the prediction ability of different instruments in use.


Production of a Statistical Handbook with guidelines for sampling of carcasses and estimation and validation of statistical methods to be used together with EU regulations when approving instruments and equations.


Develop and test indirect methods for prediction of lean meat percentage of pig carcasses.

The results and experiences obtained have been published and presented in reports and at workshops and seminars and are used as base for the Quality Assurance Program (QAP) presented in this newsletter. The QAP together with other recommendations will be used to maintain accuracy in pig carcass classification systems.


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Biology and classification

Guidelines for implementation and control

In most European countries slaughter pigs are brought to slaughter at an age of six months. Carcass weight is in the range 75 - 90 kg. Most of the slaughter pigs are crossbred with Duroc or Hampshire boars as father. In France, Germany, Spain and Belgium boars of the Pietrain breed are also used. The average lean meat percentage is in the range 55 to 60 %. The use of different breed types and variation in production systems cause variation in carcass composition and conformation. This variation must be paid attention to when classification systems are implemented.

Education and training

The quality and accuracy of classification is to a great context dependent on the skill and knowledge of the classifier. Thus the classifiers have to take part in courses and training schemes to obtain the certificate for classifiers. The education program can be organized and given by the independent organization in cooperation with the industry.

Linear measurements of back fat and loin muscle thickness are used as base for calculation of estimates of lean mean percentage. There is a need for recalibration when breeding causes changes in carcass composition and conformation.

Rules for implementation of new instruments and equations

In EU-regulations and in the Statistical Handbook, rules for performing trials for approval of new instruments or upgrading of equations are described. 

Image 2: The estimates of leanness are in most systems based on measures of fat and muscle thickness in the back.

This trial shall be performed on a representative sample of at least 120 carcasses, dissected according to the rules. The instrument and equation must fulfill the required accuracy of a minimum value of 2.5 for the RMSE (and probably for the RMSEP in the future). The butchers must be trained for the dissection to be able to follow the specifications.


With use of probes and rulers the critical control points (sources of errors) can be

The probe or ruler is not calibrated against standard

The knife on the probe tip is blunt or too narrow

The measurements are taken on wrong sites

The equation is not approved


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Available techniques and instruments for classification

Linear measures of fat and muscles thickness are used for the estimate of lean meat percentage. These measures can be taken with rulers or with probes. Measurements with rulers require split carcasses. Measures based on ultrasound techniques are taken with non-invasive probes. When the function of internal light reflectance is used, invasive probes, with a sharp knife in the tip of the probes, are used.   Instruments and classification systems with the mentioned measuring principles are available on the market.

Quality Assurance Program (QAP)

The classification of pig carcasses must be controlled by an independent organisation and by personnel at the abattoir. This control is outlined in the Quality Assurance Program, QAP.


The aim of the QAP is to assure that classification is performed in such a way that the producers and market can rely on the results and use the information as base for payment and industrial optimisation of cutting and quality.  QAP can be regarded as recommendations for national programmes outlined with more detailed rules and demands adapted to national requirements.

Personnel at the plants can perform the daily control. To assure international and national standards and performance a governmental or other independent organization shall perform the national control. The most critical control points have to be identified and specifically controlled.

The aims of the QAP is specified in the following

  • To assure that the carcasses are slaughtered and dressed according to given specifications

  • To assure that the instruments are approved and calibrated to give correct measures

  • To assure that the personnel performing the measurements are educated, trained and certified according to demands

  • To assure that the instruments operate within specifications

  • To assure that the measures of fat and muscle are taken at the specified sites on the carcass

  • To assure that the lean meat percentage obtained from the measurements are transferred correctly to the carcasses and data systems, and that the identity of the carcasses is secured.

 All control steps should be documented in a logbook, to show that the systems and instruments are in functionality according to given specifications.


As carcass weight is base for payment it is essential that dressing be performed according to given rules. The classifier has to call responsible personnel when the demands are not followed.


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The classifiers must be educated, trained and certified. The education program can be given by the industry in cooperation with an independent organization. Certification is a national responsibility.

This Quality Assurance Program is part of the classification system and shall be implemented together with all the other parts in the national system.


The EUPIGCLASS project has been accomplished during the years 2000 2003. 20 Partners from 15 European countries have been involved. The results from the project have been disseminated and published in reports, scientific articles, newsletters and at seminars and workshops.


More than 260 million pigs are slaughtered in Europe during a year. It is essential for future development of production and marketing that all carcasses are classified with reliable and accurate systems.


The classification of pig carcasses in most European countries is based on linear measures of back fat and muscle thickness. Carcass composition is expressed as lean meat percentage. Invasive or non-invasive probes are used for the linear measures.



The equations used for estimation of lean meat percentage are based on dissection trials and approved by EU. The results obtained in the project indicate that future trials need to be supervised with regard to the accuracy in dissection.


The statistical handbook will be available with guidelines for sampling, dissection and related topics for implementation of new instruments on national basis of classification. The handbook may be regarded as complement to the current EU rules.


The Quality Assurance Program, QAP, shall be regarded as the international guideline for development of national quality control programmes, adapted to the demands valid for the country. The overall control shall be performed by an independent organisation.


On the web-site all information and results from the project are made available.



This research was conducted under the EC project G6RD-CT-1999-00127

EUPIGCLASS as part of the Measurements and testing activity (Competitive and Sustainable Growth programme).