From traditional meat inspection to development of meat safety assurance programs in pig abattoirs – The European situation

Prevalence of Escherichia coli generic and pathogenic in pork meat: systematic review and meta-analysis

This research aimed to analyze scientific information regarding the prevalence of generic and pathogenic E. coli in the production and supply chain of pork meat, considering different types of samples, places of sampling, and pathotypes using a systematic review and meta-analysis tools. The meta-analysis for the prevalence of generic and pathogenic E. coli was conducted by estimating the effects within subgroups. Data subsets were analyzed using the DerSimonian-Laird method for binary random effects. The average prevalence of generic E. coli in different types of pork meat samples was determined to be 35.6% (95% CI 19.3-51.8), with no significant differences observed between pork meat and carcasses. Conversely, the average prevalence of E. coli pathotypes in samples related to the supply chain of pork meat was found to be 4.7% (95% CI 3.7-5.7). In conclusion, these findings suggest the possibility of establishing an objective threshold for E. coli prevalence as a benchmark for comparison within the meat industry. By utilizing this data, it becomes possible to propose a standardized limit that can serve as a reference point for evaluating and improving processes in the industry.

Assessment of slaughterhouse-based measures as animal welfare indicators in fattening pigs

In recent years, there has been growing interest in the assessment of animal welfare in slaughterhouses. The aim of this study was to determine the effectiveness of slaughter-based measures as animal welfare indicators and evaluate the relationships between these indicators and the sociodemographic characteristics of livestock drivers and transport conditions for fattening pigs in a commercial slaughterhouse. A total of 1,161 heavy pigs (105.6 ± 14.15 kg), from 22 commercial farms, were evaluated. Pigs were assessed ante mortem, during lairaging, by evaluating the number, location, and color of skin lesions, tail length, and the presence or absence of biting lesions, lameness, cough, rectal or vaginal prolapse, and umbilical hernia. Pulmonary lesions, pleuritis, pericarditis, and liver lesions were also recorded postmortem. A descriptive analysis was performed on antemortem and postmortem indicators to estimate their prevalence, and the relationships among antemortem and postmortem indicators were analyzed using two multilevel mixed-effects models—a linear regression and a logistic regression analysis— with the farm of origin as a fixed effect. Cough was present in 18.9% (n = 219) of pigs, whereas the prevalence of tail biting lesions (4.6%, n = 53), rectal prolapse (0.1%, n = 11), and vaginal prolapse (0.1%, n = 11) was low. As regards lesion shape, linear lesions accounted for the majority of skin lesions (55.8%, n = 648), followed by comma-shaped (34.7%, n = 403), diffuse (6.9%, n = 80), and rectangular lesions (2.5%, n = 29). Only 25.2% (n = 512) of lesions were bright red. At postmortem, pulmonary lesions were noted in 34.2 ± 13.5 (mean ± SEM) pigs, and were more prevalent in the cranial (11.9 ± 4.9) and medium lobes (12.2 ± 5.2); the caudal (5.3 ± 2.7) and accessory lobes (1.6 ± 1.6) were less affected. The number of skin lesions was significantly associated with drivers’ age, job experience (years), and marital status (p ≤ 0.001). The presence or absence of tail lesions was strongly associated with the number of skin lesions, scoring of pulmonary lesions, and animal live weight (p ≤ 0.001). Antemortem and postmortem indicators at slaughterhouses with low annual slaughter volumes can provide key information for disease monitoring and animal welfare.

Microbiological Quality of Pig Carcasses in a Slaughterhouse under Risk-Based Inspection System

Meat product inspection is one of the procedures adopted more than a century ago to guarantee food quality and safety for consumption. Due to technology and regulation advancement for farming and slaughtering pigs, a change in zoonotic profile attributed to pork has been identified. Thus, a global movement began to establish inspection parameters based on epidemiological risk profiles, culminating in the publication of a new regulation in Brazil in 2018. This normative instruction establishes that slaughterhouses under federal inspection must implement risk-based inspection until 2028. Changes in the inspection system can generate questions and objections on the part of customers and consumer markets. In order to assess microbiological contamination when adopting a risk-based inspection system, the occurrence of Salmonella spp. and the quantification of Enterobacteriaceae and mesophilic aerobic counts were compared in pig carcasses slaughtered under traditional and risk-based inspection systems. A statistical significance reduction was identified regarding the quantification of Enterobacteriaceae (log -0.18 to -1.61 CFU/cm²) and mesophilic aerobic counts (log 4.60 to 3.49 CFU/cm²). The occurrence of Salmonella spp. did not show a significant difference (4% to 5.3%). The results allowed us to conclude that adopting risk-based inspection systems improves food safety through Enterobacteriaceae and mesophilic aerobic counts reduction.

Evaluation of a Harmonized Undergraduate Catalog for Veterinary Public Health and Food Hygiene Pedagogy in Europe

Current and emerging veterinary public health (VPH) challenges raised by globalization, climate change, and industrialization of food production require the veterinarian's role to evolve in parallel and veterinary education to adapt to reflect these changes. The European Food Hygiene catalog was developed to provide a list of topics relevant to Day One Competencies in VPH. A study was undertaken to ensure that the catalog and teaching practices were pertinent to the work of public health veterinarians. Relevant stakeholders were consulted using questionnaires and semi-structured interviews. A long questionnaire was distributed to 49 academics teaching VPH in European veterinary schools to review topics listed in the catalog. Eighteen responses were received (36.7%), representing 12 European countries. There was general agreement that most topics were appropriate for the undergraduate VPH curriculum. A short questionnaire was distributed to 348 European veterinarians working in the industry. Twenty-four questionnaires (6.7%) were received, representing eight European countries. Despite the low participation rate, topics needing greater emphasis in the undergraduate curriculum included Hazard Analysis Critical Control Points (HACCP), food microbiology, and audits. Seven semi-structured interviews with public health veterinarians working in the UK identified the need for curricular changes including greater practical experience and a shift from a focus on meat inspection to risk management. This may be partly achieved by replacing traditional lectures with authentic case-based scenarios. The study findings can be used to inform the future direction to VPH education for veterinary students across Europe.

Risk factors and the overall characterization of Yersinia enterocolitica as an initial model of pathogen surveillance in the pig production system in Serbia

A survey was undertaken to determine the overall prevalence of Yersinia enterocolitica in pigs of slaughter age and to characterize the isolates in relation to bio-serotype, the presence of virulence genes, genetic diversity, and antimicrobial resistance. Moreover, possible risk factors associated with Y. enterocolitica infection during the pre-harvested and harvested phase of pig production were studied. The overall Y. enterocolitica prevalence in the pigs was 10.4% (95% confidence interval, CI = 8.5-12.3%). The most common Y. enterocolitica bio-serotype was 4/O:3, accounting for 81.6% of investigated isolates. The pathogenicity of 63 Y. enterocolitica 4/O:3 isolates, originating from all infected farms, was confirmed by the presence of both the ail and ystA virulence-associated genes and the absence of ystB gene (100%). Characterization with PFGE of 63 confirmed Y. enterocolitica 4/O:3 isolates identified five different genotypes with shared identical genetic profiles (100% similarity) within each genotype. Isolates originating from farrow-to-finish farms were only resistant to ampicillin, while resistance to nalidixic acid, tetracycline, and chloramphenicol at fattening farms was also observed. Risk factors related to Y. enterocolitica pig infection include fattening farms (odds ratio, OR = 2.3, 95% CI = 1.4-3.8, P < 0.001), a 3-6 h lairage period (OR = 1.6, 95% CI = 1.0-2.6, P = 0.035) and winter season (OR = 3.8, 95% CI = 2.0-7.4, P < 0.001). In addition to the overall characterization of Y. enterocolitica isolates, identification of the main risks associated with infection allows better application of preventive measures to reduce the occurrence and distribution of Y. enterocolitica infection.

Systematic Review and Meta-Analysis of the Efficacy of Interventions Applied during Primary Processing to Reduce Microbial Contamination on Pig Carcasses

Interventions from lairage to the chilling stage of the pig slaughter process are important to reduce microbial contamination of carcasses. The aim of this systematic review and meta-analysis was to assess the effectiveness of abattoir interventions in reducing aerobic colony count (ACC), Enterobacteriaceae, generic Escherichia coli, and Yersinia spp. on pig carcasses. The database searches spanned a 30 year period from 1990 to 2021. Following a structured, predefined protocol, 22 articles, which were judged as having a low risk of bias, were used for detailed data extraction and meta-analysis. The meta-analysis included data on lairage interventions for live pigs, standard processing procedures for pig carcasses, prechilling interventions, multiple carcass interventions, and carcass chilling. Risk ratios (RRs) for prevalence studies and mean log differences (MDs) for concentration outcomes were calculated using random effects models. The meta-analysis found that scalding under commercial abattoir conditions effectively reduced the prevalence of Enterobacteriaceae (RR: 0.05, 95% CI: 0.02 to 0.12, I² = 87%) and ACC (MD: -2.84, 95% CI: -3.50 to -2.18, I² = 99%) on pig carcasses. Similarly, significant reductions of these two groups of bacteria on carcasses were also found after singeing (RR: 0.25, 95% CI: 0.14 to 0.44, I² = 90% and MD: -1.95, 95% CI: -2.40 to -1.50, I² = 96%, respectively). Rectum sealing effectively reduces the prevalence of Y. enterocolitica on pig carcasses (RR: 0.60, 95% CI: 0.41 to 0.89, I² = 0%). Under commercial abattoir conditions, hot water washing significantly reduced ACC (MD: -1.32, 95% CI: -1.93 to -0.71, I² = 93%) and generic E. coli counts (MD: -1.23, 95% CI: -1.89 to -0.57, I² = 61%) on pig carcasses. Conventional dry chilling reduced Enterobacteriaceae prevalence on pig carcasses (RR: 0.32, 95% CI: 0.21 to 0.48, I² = 81%). Multiple carcass interventions significantly reduced Enterobacteriaceae prevalence (RR: 0.11, 95% CI: 0.05 to 0.23, I² = 94%) and ACC on carcasses (MD: -2.85, 95% CI: -3.33 to -2.37, I² = 97%). The results clearly show that standard processing procedures of scalding and singeing and the hazard-based intervention of hot water washing are effective in reducing indicator bacteria on pig carcasses. The prevalence of Y. enterocolitica on pig carcasses was effectively reduced by the standard procedure of rectum sealing; nevertheless, this was the only intervention for Yersinia investigated under commercial conditions. High heterogeneity among studies and trials investigating interventions and overall lack of large, controlled trials conducted under commercial conditions suggest that more in-depth research is needed.

Physical Hazards in Aepyceros melampus Carcasses Killed for Meat Purposes by Aerial and Thoracic Shots

Physical hazards, such as bullet particles and bone fragments, in wild meat could be introduced by processes applied whilst killing game meat animals. These hazards may pose a health risk to non-suspecting consumers and must therefore be identified, evaluated and removed from meat and meat products. The extent of dispersion of these hazards in carcasses has not been sufficiently investigated with respect to game meat safety. This study aims to describe and quantify the occurrence of these hazards in animals shot by aerial (helicopter) shotgun targeting the head and higher neck region (n = 12) and single-projectile/free-bullet rifle shots targeting the thorax region (n = 36) of impala killed for meat consumption. To quantify the occurrence, particle sizes and dispersion surface of bullet fragments and bone splinters in the forequarters, radiographs were taken from top to bottom (dorsal ventral) and from the side (lateral) in the sequence of the skull, neck and forequarters. A t-test (p < 0.05) was conducted to compare the association of averages from the killing methods with the occurrences of bullet fragments and bone splinters. Bullet particles and bone splinters of significant sizes were introduced by the killing methods adopted. The results show a high incidence of harmful bullet particle and bone splinter sizes from the rifle thorax shots (p = 0.005). The dispersion of both physical hazards could cover a wide distance of >332 mm between particles on hunted game meat animals. Game meat animal killing methods with a rifle targeting the chest cavity should be refined and implemented. These should include the selection of bullets less prone to fragmentation, and compliance with regulated game meat animal-killing protocols, including regulating the placement of shots to allow only head or high neck shots for game meat animals slaughtered/culled for human consumption.

Adding value to food chain information: using data on pig welfare and antimicrobial use on-farm to predict meat inspection outcomes

BACKGROUND

Using Food Chain Information data to objectively identify high-risk animals entering abattoirs can represent an important step forward towards improving on-farm animal welfare. We aimed to develop and evaluate the performance of classification models, using Gradient Boosting Machine algorithms that utilise accurate longitudinal on-farm data on pig health and welfare to predict condemnations, pluck lesions and low cold carcass weight at slaughter.

RESULTS

The accuracy of the models was assessed using the area under the receiver operating characteristics (ROC) curve (AUC). The AUC for the prediction models for pneumonia, dorsocaudal pleurisy, cranial pleurisy, pericarditis, partial and total condemnations, and low cold carcass weight varied from 0.54 for pneumonia and 0.67 for low cold carcass weight. For dorsocaudal pleurisy, ear lesions assessed on pigs aged 12 weeks and antimicrobial treatments (AMT) were the most important prediction variables. Similarly, the most important variable for the prediction of cranial pleurisy was the number of AMT. In the case of pericarditis, ear lesions assessed both at week 12 and 14 were the most important variables and accounted for 33% of the Bernoulli loss reduction. For predicting partial and total condemnations, the presence of hernias on week 18 and lameness on week 12 accounted for 27% and 14% of the Bernoulli loss reduction, respectively. Finally, AMT (37%) and ear lesions assessed on week 12 (15%) were the most important variables for predicting pigs with low cold carcass weight.

CONCLUSIONS

The findings from our study show that on farm assessments of animal-based welfare outcomes and information on antimicrobial treatments have a modest predictive power in relation to the different meat inspection outcomes assessed. New research following the same group of pigs longitudinally from a larger number of farms supplying different slaughterhouses is required to confirm that on farm assessments can add value to Food Chain Information reports.

Meat Safety from Farm to Slaughter—Risk-Based Control of Yersinia enterocolitica and Toxoplasma gondii

The implementation of the traditional meat safety control system has significantly contributed to increasing food safety and public health protection. However, several biological hazards have emerged in meat production, requiring a comprehensive approach to their control, as traditional methods of meat inspection at the slaughterhouse are not able to detect them. While national control programs exist for the most important meat-related hazards, similar data are still lacking for certain neglected threats, such as Yersinia enterocolitica or Toxoplasma gondii. The obstacle in controlling these hazards in the meat chain is their presence in latently infected, asymptomatic animals. Their effective control can only be achieved through systematic preventive measures, surveillance or monitoring, and antimicrobial interventions on farms and in slaughterhouses. To establish such a system, it is important to collect all relevant data on hazard-related epidemiological indicators from the meat chain, which should provide relevant guidance for interventions at the harvest and post-harvest stage. The proposed approach is expected to improve the existing system and provide many opportunities to improve food safety and public health.

Implementation of Visual-Only Swine Inspection in the European Union: Challenges, Opportunities, and Lessons Learned

ABSTRACT

Consumption of contaminated meat and poultry products is a major source of foodborne illness in the United States and globally. Meat inspection procedures, established more than 100 years ago to detect prevailing food safety issues of the time and largely harmonized around the world, do not effectively detect modern hazards and may inadvertently increase food safety risks by spreading contamination across carcasses. Visual-only inspection (VOI) is a significantly different, modernized meat inspection system that is data driven and minimizes physical manipulation of the carcass during inspection. It was developed based on scientific evidence and risk assessment and aims to better control current food safety hazards. In 2014, the European Union (EU) became the first supranational government in the world to require VOI for all swine herds slaughtered in member states that met certain epidemiologic and animal rearing conditions. Here, we review the implementation of this new inspection system with the goal of informing similar modernization efforts in other countries and for other commodities beyond pork. This article reports the results of a literature review and interviews conducted with nine experts in 2018 on the implementation of the EU's 2014 VOI regulation. Challenges, opportunities, and lessons learned about the implementation of the regulation are described for audiences interested in adapting inspection procedures to prevent and detect modern food safety hazards. Overall, implementation of VOI varies within and across member states, and among slaughterhouses of different sizes. This variation is due to disease risk patterns, supply chain conditions, and trade barriers. Before transitioning to a similar risk-based meat inspection system, other countries should consider the following: science-based research agendas to identify what food chain information best predicts herd health and foodborne hazards, regulatory system design that accurately reflects local hazards, and development of targeted VOI educational materials.

HIGHLIGHTS

A Retrospective Study after 10 Years (2010-2019) of Meat Inspection Activity in a Domestic Swine Abattoir in Tuscany: The Slaughterhouse as an Epidemiological Observatory

Simple Summary

Veterinarians belonging to the Health Authorities are responsible for the safety of food of animal origin. The control activities performed at the slaughterhouse comprise inspections before and after slaughtering to verify the health and welfare of the animals and the wholesomeness of the animal products. In this study, data deriving from ten years (2010–2019) of meat inspection activity in a pig slaughterhouse in Tuscany (Italy) were analyzed to investigate the frequencies of death during transport of whole carcass and partial condemnations and their causes. In total 1,246,309 pigs from 8 different regions of Central and Northern Italy were slaughtered. The mortality rate was found to be lower than the threshold internationally recommended to ensure animal welfare and in line with the mortality values reported at the European level. Overalls 372 carcasses were condemned mainly due to erysipelas, generalized jaundice, lipomatous pseudohypertrophy, generalized abscesses, acute or generalized enteritis, and peritonitis. As regards partial condemnations, liver, lungs, and kidney were the most frequently condemned organs. The results of this study describe a non-worrying situation as regards to the investigated aspects and confirm the slaughterhouse as a privileged observation point for monitoring the trend of the main diseases over time, the results of the efforts for their control, and also the compliance with animal welfare standards.

Abstract

The activities performed by the Official Veterinarian at the slaughterhouse represent a useful source of data for the control of issues affecting human and animal health and welfare. This study analyzed the data deriving from ten years (2010–2019) of meat inspection in a pig slaughterhouse in Tuscany (Italy) to investigate the transport mortality rate and the frequencies and main causes of whole carcass and partial condemnations. In total, 1,246,309 pigs were slaughtered from 8 different regions of Central and Northern Italy. Overall, 1153 pigs died during transport (mortality rate 0.09%). Whole carcass condemnation affected 372 carcasses (0.03%), mainly due to erysipelas, generalized jaundice, lipomatous pseudohypertrophy, generalized abscesses, acute or generalized enteritis, and peritonitis. As regards partial condemnations, the liver was the most frequently condemned (~30% of the pigs), followed by lungs (17.3%), heart (6.9%), and kidney (0.9%). The main causes were “milk spot liver” and perihepatitis for the liver; pneumonia and pleurisy for the lungs; pericarditis and polyserositis for the heart; and polycystic kidney and nephritis for kidneys. The results of this study describe a non-worrying situation as regards the investigated aspects and confirm the slaughterhouse as a valid epidemiological observatory for monitoring the trend of the main diseases over time, the results of the efforts for their control, and the compliance with animal welfare standards.

Assessment of Animal-Based Pig Welfare Outcomes on Farm and at the Abattoir: A Case Study

The study assessed the prevalence of animal-based pig welfare outcomes on one Chilean farm and one abattoir. A total of 198 pens of slaughter pigs (9,049 pigs) were observed on farm and 54 batches (8,843 pigs) were observed at the abattoir. All assessments were conducted from outside the pen on farm and from outside the corridor where pigs were unloaded from the truck at the abattoir. Batch size and number of pigs with ear, tail and skin lesions, hernias, rectal prolapse, bursitis, and lameness were recorded. Data were analyzed using generalized linear mixed models. There was a large variation among pens on farm and among batches at the abattoir for all outcomes. Bursitis was the most prevalent outcome recorded in both locations, followed by ear lesions recorded on farm and by tail lesions recorded at the abattoir. Ear lesions' prevalence was higher on farm (P < 0.001), while tail lesions, hernia, and bursitis prevalence were higher at the abattoir (P < 0.001). Ear lesions' prevalence on farm was higher in female and mixed-sex groups than in male groups (P < 0.01), but male groups tended to have a higher tail lesions' prevalence (P < 0.1). The results show a difference in welfare outcomes, suggesting that assessment of outcomes on farm could complement ante-mortem inspections at the abattoir. However, as the same animals were not inspected in the two locations and there is the possibility of a seasonal influence on the results, the findings should be interpreted with caution and further research is required.

Use of meat juice and blood serum with a miniaturised protein microarray assay to develop a multi-parameter IgG screening test with high sample throughput potential for slaughtering pigs

BACKGROUND

Serological screening of pig herds at the abattoir is considered a potential tool to improve meat inspection procedures and herd health management. Therefore, we previously reported the feasibility of a miniaturised protein microarray as a new serological IgG screening test for zoonotic agents and production diseases in pigs. The present study investigates whether the protein microarray-based assay is applicable for high sample throughput using either blood serum or meat juice.

MATERIAL AND METHODS

Microarrays with 12 different antigens were produced by Abbott (formerly Alere Technologies GmbH) Jena, Germany in a previously offered 'ArrayTube' platform and in an 'ArrayStrip' platform for large-scale use. A test protocol for the use of meat juice on both microarray platforms was developed. Agreement between serum and meat juice was analysed with 88 paired samples from three German abattoirs. Serum was diluted 1:50 and meat juice 1:2. ELISA results for all tested antigens from a preceding study were used as reference test to perform Receiver Operating Characteristic analysis for both test specimens on both microarray platforms.

RESULTS

High area under curve values (AUC > 0.7) were calculated for the analysis of T. gondii (0.87), Y. enterocolitica (0.97), Mycoplasma hyopneumoniae (0.84) and Actinobacillus pleuropneumoniae (0.71) with serum as the test specimen and for T. gondii (0.99), Y. enterocolitica (0.94), PRRSV (0.88), A. pleuropneumoniae (0.78) and Salmonella spp. (0.72) with meat juice as the test specimen on the ArrayStrip platform. Cohens kappa values of 0.92 for T. gondii and 0.82 for Y. enterocolitica were obtained for the comparison between serum and meat juice. When applying the new method in two further laboratories, kappa values between 0.63 and 0.94 were achieved between the laboratories for these two pathogens.

CONCLUSION

Further development of a miniaturised pig-specific IgG protein microarray assay showed that meat juice can be used on microarray platforms. Two out of twelve tested antigens (T. gondii, Y. enterocolitica) showed high test accuracy on the ArrayTube and the ArrayStrip platform with both sample materials.

Red Wine and Garlic as a Possible Alternative to Minimize the Use of Nitrite for Controlling Clostridium Sporogenes and Salmonella in a Cured Sausage: Safety and Sensory Implications

The use of nitrite in meat products has been questioned due to its potential association with colon cancer. This work aimed to evaluate the behavior of Clostridium sporogenes (used as a surrogate for Cl. botulinum) and Salmonella in a dry-cured sausage, chouriço, made with and without nitrite and nitrate or with red wine and garlic, and to study the sensory implications through a consumer test. The survival of Cl. sporogenes and Salmonella was determined mainly by the reduction in water activity (aw), but the use of wine or wine and garlic contributed to the control of Salmonella during processing. The challenge test with Cl. sporogenes revealed no effect of the curing salts, wine, or garlic on the population of this microorganism. The use of curing salts resulted in a more reddish color that was recognized by the consumer as over-cured and artificial when compared with chouriço made with wine or wine and garlic, which were better rated in the hedonic test. In cured sausages of small caliber, the use of nitrite might be reconsidered, as the values of aw necessary to inhibit Clostridium toxinogenesis and growth are achieved rapidly.

Risk-based surveillance for meat-borne parasites

There is a plethora of meat-borne hazards - including parasites - for which there may be a need for surveillance. However, veterinary services worldwide need to decide how to use their scarce resources and prioritise among the perceived hazards. Moreover, to remain competitive, food business operators - irrespective of whether they are farmers or abattoir operators - are preoccupied with maintaining a profit and minimizing costs. Still, customers and trade partners expect that meat products placed on the market are safe to consume and should not bear any risks of causing disease. Risk-based surveillance systems may offer a solution to this challenge by applying risk analysis principles; first to set priorities, and secondly to allocate resources effectively and efficiently. The latter is done through a focus on the cost-effectiveness ratio in sampling and prioritisation. Risk-based surveillance was originally introduced into veterinary public health in 2006. Since then, experience has been gathered, and the methodology has been further developed. Guidelines and tools have been developed, which can be used to set up appropriate surveillance programmes. In this paper, the basic principles are described, and by use of a surveillance design tool called SURVTOOLS (https://survtools.org/), examples are given covering three meat-borne parasites for which risk-based surveillance is 1) either in place in the European Union (EU) (Trichinella spp.), 2) to be officially implemented in December 2019 (Taenia saginata) or 3) only carried out by one abattoir company in the EU as there is no official EU requirement (Toxoplasma gondii). Moreover, advantages, requirements and limitations of risk-based surveillance for meat-borne parasites are discussed.