Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Description and determinants of the faecal resistome and microbiome of farmers and slaughterhouse workers : A metagenome-wide cross-sectional study
    Gompel, Liese Van; Luiken, Roosmarijn E.C. ; Hansen, Rasmus B. ; Munk, Patrick ; Bouwknegt, Martijn ; Heres, Lourens ; Greve, Gerdit D. ; Scherpenisse, Peter ; Jongerius-Gortemaker, Betty G.M. ; Tersteeg-Zijderveld, Monique H.G. ; García-Cobos, Silvia ; Dohmen, Wietske ; Dorado-García, Alejandro ; Wagenaar, Jaap A. ; Urlings, Bert A.P. ; Aarestrup, Frank M. ; Mevius, Dik J. ; Heederik, Dick J.J. ; Schmitt, Heike ; Bossers, Alex ; Smit, Lidwien A.M. - \ 2020
    Environment International 143 (2020). - ISSN 0160-4120
    Antimicrobial resistance - Farmers - Microbiome - Occupational exposure - Resistome - Slaughterhouse workers

    Background: By studying the entire human faecal resistome and associated microbiome, the diversity and abundance of faecal antimicrobial resistance genes (ARGs) can be comprehensively characterized. Prior culture-based studies have shown associations between occupational exposure to livestock and carriage of specific antimicrobial resistant bacteria. Using shotgun metagenomics, the present study investigated 194 faecal resistomes and bacteriomes from humans occupationally exposed to ARGs in livestock (i.e. pig and poultry farmers, employees and family members and pig slaughterhouse workers) and a control population (Lifelines cohort) in the Netherlands. In addition, we sought to identify determinants for the human resistome and bacteriome composition by applying a combination of multivariate (NMDS, PERMANOVA, SIMPER and DESeq2 analysis) and multivariable regression analysis techniques. Results: Pig slaughterhouse workers and pig farmers carried higher total ARG abundances in their stools compared to broiler farmers and control subjects. Tetracycline, β-lactam and macrolide resistance gene clusters dominated the resistome of all studied groups. No significant resistome alpha diversity differences were found among the four populations. However, the resistome beta diversity showed a separation of the mean resistome composition of pig and pork exposed workers from broiler farmers and controls, independent of their antimicrobial use. We demonstrated differences in resistome composition between slaughter line positions, pig versus poultry exposed workers, as well as differences between farmers and employees versus family members. In addition, we found a significant correlation between the bacteriome and resistome, and significant differences in the bacteriome composition between and within the studied subpopulations. Finally, an in-depth analysis of pig and poultry farms – of which also farm livestock resistomes were analysed – showed positive associations between the number of on-farm working hours and human faecal AMR loads. Conclusion: We found that the total normalized faecal ARG carriage was larger in persons working in the Dutch pork production chain compared to poultry farmers and controls. Additionally, we showed significant differences in resistome and bacteriome composition of pig and pork exposed workers compared to a control group, as well as within-population (farms, slaughterhouse) compositional differences. The number of on-farm working hours and the farm type (pig or broiler) that persons live or work on are determinants for the human faecal resistome. Overall, our results may suggest direct or indirect livestock contact as a determinant for human ARG carriage. Future studies should further focus on the connection between the human and livestock resistome (i.e. transmission routes) to substantiate the evidence for livestock-associated resistome acquisition.

    Low growth resilience to drought is related to future mortality risk in trees
    DeSoto, Lucía ; Cailleret, Maxime ; Sterck, Frank ; Jansen, Steven ; Kramer, Koen ; Robert, Elisabeth M.R. ; Aakala, Tuomas ; Amoroso, Mariano M. ; Bigler, Christof ; Camarero, J.J. ; Čufar, Katarina ; Gea-Izquierdo, Guillermo ; Gillner, Sten ; Haavik, Laurel J. ; Hereş, Ana Maria ; Kane, Jeffrey M. ; Kharuk, Vyacheslav I. ; Kitzberger, Thomas ; Klein, Tamir ; Levanič, Tom ; Linares, Juan C. ; Mäkinen, Harri ; Oberhuber, Walter ; Papadopoulos, Andreas ; Rohner, Brigitte ; Sangüesa-Barreda, Gabriel ; Stojanovic, Dejan B. ; Suárez, Maria Laura ; Villalba, Ricardo ; Martínez-Vilalta, Jordi - \ 2020
    Nature Communications 11 (2020)1. - ISSN 2041-1723

    Severe droughts have the potential to reduce forest productivity and trigger tree mortality. Most trees face several drought events during their life and therefore resilience to dry conditions may be crucial to long-term survival. We assessed how growth resilience to severe droughts, including its components resistance and recovery, is related to the ability to survive future droughts by using a tree-ring database of surviving and now-dead trees from 118 sites (22 species, >3,500 trees). We found that, across the variety of regions and species sampled, trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. In angiosperms, drought-related mortality risk is associated with lower resistance (low capacity to reduce impact of the initial drought), while it is related to reduced recovery (low capacity to attain pre-drought growth rates) in gymnosperms. The different resilience strategies in these two taxonomic groups open new avenues to improve our understanding and prediction of drought-induced mortality.

    Large-scale serological screening of slaughter pigs for Toxoplasma gondii infections in The Netherlands during five years (2012-2016): Trends in seroprevalence over years, seasons, regions and farming systems
    Swanenburg, M. ; Gonzales Rojas, Jose ; Bouwknegt, M. ; Boender, G.J. ; Oorburg, D. ; Heres, L. ; Wisselink, H.J. - \ 2019
    Veterinary Parasitology 2 (2019). - ISSN 0304-4017
    Toxoplasma gondii is the causative agent of the parasitic disease toxoplasmosis, which is an important foodborne zoonosis. Eating undercooked meat of infected animals, including pigs, has been considered the major transmission route of T. gondii to humans. Therefore, it is urgent to develop and implement intervention measures in the pork meat chain to reduce risks of acquiring a T. gondii infection. Proposed measures for control of T. gondii in pigs include serological testing of pigs and audits of pig farms on risk factors for T. gondii infection. So far, these ideas have not been tested in practice. In order to generate knowledge about the epidemiology and seroprevalence of T. gondii, as a basis for developing a surveillance system, we studied the long term seroprevalence over years, farming systems and regions, and seasonal patterns of T. gondii seroprevalence in Dutch slaughter pigs. During a five year study period from 2012 to 2016, serum samples were routinely collected in five Dutch pig slaughterhouses. The sera were tested in an ELISA for the presence of antibodies against Toxoplasma. In total 226,340 serum samples were collected and tested during the study period. The observed seroprevalence varied over years, with the highest overall seroprevalence in 2014 (2.8%) and the lowest in 2016 (1.4%). A higher seroprevalence was observed in pigs from organic farms compared to pigs from conventional farms. The overall risk of infection was on average 2.63 times significantly (p < 0.001) higher for organically raised pigs than for conventionally raised pigs. A seasonal pattern in seroprevalence was observed: the results showed a dominant annual periodicity with a seroprevalence peak in winter around week 1 and a minimum seroprevalence in summer around week 27. To our knowledge, this is the first large scale study on the seroprevalence of T. gondii in slaughter pigs. In comparison to other European serological studies, the observed seroprevalence seems to be relatively low. However, care is needed when comparing the results with other studies because of differences in test setup, the number of samples and time period of sampling. The results can be used as a starting point for developing a surveillance system for T. gondii, and for implementation of intervention measures.
    Study on inactivation of porcine epidemic diarrhoea virus, porcine sapelovirus 1 and adenovirus in the production and storage of laboratory spray-dried porcine plasma
    Hulst, M.M. ; Heres, L. ; Hakze-van der Honing, R.W. ; Pelser, M. ; Fox, M. ; Poel, W.H.M. van der - \ 2019
    Journal of Applied Microbiology 126 (2019)6. - ISSN 1364-5072 - p. 1931 - 1943.
    adenovirus - feed-safety - porcine epidemic diarrhoea virus - porcine sapelo virus 1 - spray-dried porcine plasma - thermal and physical inactivation

    Aim: Evaluation of the thermal and physical conditions for inactivation of adenovirus (AdV), porcine sapelovirus 1 (PSV1) and the economically important viruses porcine epidemic diarrhoea virus (PEDV) and porcine circovirus 2 (PCV2) in the production of spray-dried porcine plasma (SDPP). Methods and Results: Citrate-treated porcine plasma of pH 7·5, 9·8 and 10·2 (8·5% dry-matter) was spiked with PEDV, PSV1, PCV2 and AdV and incubated at 3°C for maximum 24 h, and at 44 or 48°C for maximum 10 min (Experiment 1). Spiked citrate-treated concentrated plasma of pH 7·5 and 9·8 (24% dry-matter) was spray dried in a laboratory scale apparatus (Experiment 2). Aliquots of SDPP were stored over a period of 0–10 weeks at 11 and 20°C (Experiment 3). Reverse transcription(RT)-quantitative PCR detected no notable reduction in viral genomes in treated plasma and SDPP samples. No infectious PSV1 was re-isolated from plasma and SDPP samples in cell culture. At pH 10·2 and 3°C, infectivity of PEDV in plasma was reduced with a reduction factor of 4·2 log 10 (LRF) at 10 h contact time, whereas heating to 44°C for at least 1 min at alkali pH was needed to achieve a LRF of 4·2 for AdV. Spray drying at an outlet temperature of 80°C reduced AdV infectivity effectively (LRF = 5·2) and PEDV infectivity for 95% (LRF = 1·4). After storage at 20°C for 2 weeks no infectious PEDV was re-isolated from SDPP anymore (LRF ≥4·0). Due to growth of antibiotic-resistant bacteria from plasma in cell cultures used for PCV2 isolation, no data regarding inactivation of PCV2 were obtained. Conclusions: Five percent of PEDV stayed infectious after our spray drying conditions. Spray drying in combination with storage for ≥2 weeks at 20°C eliminated infectivity of PEDV effectively. Significance and Impact of the Study: The conditions for inactivation of virus in plasma and SDPP determined are important for producers to inactivate PEDV during production of SDPP.

    Samenvatting ESBL-Attributieanalyse (ESBLAT) : Op zoek naar de bronnen van antibioticaresistentie bij de mens
    Mevius, Dik ; Heederik, Dick ; Duijkeren, Engeline ; Veldman, Kees ; Essen, Alieda van; Kant, Arie ; Liakopoulos, Apostolos ; Geurts, Yvon ; Pelt, Wilfrid van; Mughini Gras, Lapo ; Schmitt, Heike ; Dierikx, Cindy ; Hoek, Angela van; Evers, Eric ; Roda Husman, Annemaria de; Blaak, Hetty ; Dissel, Jaap van; Smid, Joost ; Dohmen, Wietske ; Dorado-Garcia, Alejandro ; Havelaar, Arie ; Hordijk, Joost ; Wagenaar, Jaap ; Fluit, Ad ; Bunt, Gerrita van den; Bonten, Marc ; Velthuis, Annet ; Heuvelink, Annet ; Buter, Rianne ; Gonggrijp, Maaike ; Santman-Berends, Inge ; Lam, Theo ; Urlings, Bert ; Heres, Lourens ; Bouwknecht, Martijn ; Groot, Jacques de - \ 2018
    Netherlands : De Stichting TKI Agri&Food (TKI) - 11 p.
    Rapport ESBL-Attributieanalyse (ESBLAT) : Op zoek naar de bronnen van antibioticaresistentie bij de mens
    Mevius, Dik ; Heederik, Dick ; Duijkeren, Engeline ; Veldman, Kees ; Essen, Alieda van; Kant, Arie ; Liakopoulos, Apostolos ; Geurts, Yvon ; Pelt, Wilfrid van; Mughini Gras, Lapo ; Schmitt, Heike ; Dierikx, Cindy ; Hoek, Angela van; Evers, Eric ; Roda Husman, Annemaria de; Blaak, Hetty ; Dissel, Jaap van; Smid, Joost ; Dohmen, Wietske ; Dorado-Garcia, Alejandro ; Havelaar, Arie ; Hordijk, Joost ; Wagenaar, Jaap ; Fluit, Ad ; Bunt, Gerrita van den; Bonten, Marc ; Velthuis, Annet ; Heuvelink, Annet ; Buter, Rianne ; Gonggrijp, Maaike ; Santman-Berends, Inge ; Lam, Theo ; Urlings, Bert ; Heres, Lourens ; Bouwknecht, Martijn ; Groot, Jacques de - \ 2018
    Netherlands : De Stichting TKI Agri&Food (TKI) - 73
    ESBL carriage in pig slaughterhouse workers is associated with occupational exposure
    Dohmen, W. ; Gompel, L. Van; Schmitt, H. ; Liakopoulos, A. ; Heres, L. ; Urlings, B.A. ; Mevius, D. ; Bonten, M.J.M. ; Heederik, D.J.J. - \ 2017
    Epidemiology and Infection 145 (2017)10. - ISSN 0950-2688 - p. 2003 - 2010.
    Antimicrobial resistance - bla - occupational epidemiology - pig abattoir workers - zoonosis
    We investigated the prevalence of extended-spectrum β-lactamase (ESBL) carriage in slaughterhouse workers and the association with occupational exposure to slaughter animals and products. Stool samples from 334 employees in a Dutch pig slaughterhouse were obtained. Presence of ESBL was determined by selective plating, microarray analysis, and gene sequencing. Questionnaires were used to collect personal and occupational information. The overall prevalence of ESBL carriage was 4·8% (16/334). All ESBL-producing isolates were Escherichia coli. The ESBL genes detected were bla CTX-M-1 (n = 8), bla CTX-M-15 (n = 3), bla CTX-M-27 (n = 2), bla CTX-M-24 (n = 1), bla CTX-M-55 (n = 1), and bla SHV-12 (n = 1). A higher prevalence of ESBL was seen in workers in jobs with as tasks ‘removal of lungs, heart, liver, tongue’ (33%), and ‘removal of head and spinal cord’ (25%). For further analysis, participants were divided in two groups based on potential exposure to ESBL as related to their job title. One group with an assumed higher exposure to ESBL (e.g. stable work, stabbing, dehairing, removal of organs) and another group with an assumed lower exposure to ESBL (e.g. refrigeration, packaging and expedition). In the ‘higher exposure’ group, ten out of 95 (10·5%) were carrying ESBL vs. six out of 233 (2·6%) in the ‘lower exposure’ group. Human ESBL carriage was significantly associated with job exposure in the slaughterhouse (OR 4·5, CI 1·6–12·6). Results suggest that ESBL carriage in slaughterhouse workers overall is comparable with the Dutch population. Within the slaughterhouse population a difference in carriage exists depending on their position along the slaughter line and tasks involved.
    Mechanistic in-vitro study on spray dried plasma as alternative against weaning diarrhea
    Hulst, M.M. ; Wit, A.A.C. de; Doremalen, A.M.H. van; Heres, L. ; Vuure, C. van - \ 2016
    Evaluation of producing and marketing entire male pigs
    Backus, G.B.C. ; Broek, E.M.F. van den; Fels, J.B. van der; Heres, L. ; Immink, V.M. ; Kornelis, M. ; Mather, P.K. ; Peet-Schwering, Carola van der; Riel, Johannes van; Snoek, H.M. ; Smet, A. de; Tacken, G.M.L. ; Valeeva, N.I. ; Wagenberg, C.P.A. van - \ 2016
    NJAS Wageningen Journal of Life Sciences 76 (2016). - ISSN 1573-5214 - p. 29 - 41.
    Boars; - Castration; - Detection; - Behaviour; - Consumer acceptance; - Breeding

    This paper presents the results of a research program that was aimed at evaluating: (1) sensory evaluation of meat from entire male pigs, (2) preventive measures to reduce boar taint prevalence, (3) accuracy of detection for boar taint, and (4) the relationship between farm management characteristics and levels of mounting and aggressive behaviour of boars. Using observational and experimental studies data were collected in various segments of the pork supply chain. Consumer acceptance of meat from entire male pigs was evaluated. The effectiveness of preventive measures to reduce boar taint prevalence was determined. The relationship of farm (management) characteristics with boar taint prevalence, animal behaviour, skin lesions and lameness respectively was analysed. The similarity of the rank order between consumer perception of odour and human nose scores, skatole and androstenone levels respectively was determined. Consumers evaluate meat that passed the boar taint detection test comparable to meat from gilts. Meat samples that did not pass this test were evaluated less favourable. Ranking AI boars on their genomic breeding values for low boar taint resulted in a reduction in boar taint prevalence of 40%. The skatole level is lower in boars fed via a long trough than in boars fed by a single space feeder. Few eating places, restricted feeding, a low level of amino acids in the diet, insufficient water supply of the drinking system, illness of the pigs, a suboptimal climate and fear for humans were associated with a higher level of sexual and aggressive behaviour and more skin lesions. A partly open pen wall, clean pens and pigs, wider gaps of the slats, feeding by a long trough, and feeding wet by-products were associated with less sexual and aggressive behaviour and less skin lesions. Having more than 30 animals per pen was associated with a higher probability of high boar taint prevalence levels. Hygienic conditions were associated with lower boar taint prevalence levels. Assessing similarity of the rank order comparison between consumer perception and three selected boar taint detection parameters for the consumer perception attribute odour of meat resulted in the highest Kendall's W values for the human nose scores. In conclusion, boar tainted meat was rated as less pleasant by consumers compared to meat of gilts and non-tainted boar meat, indicating the need of detection as a safety net at the slaughter line. Breeding was an effective preventive measure to reduce boar taint. Farms with appropriate management, feeding and housing conditions have reduced levels of mounting and aggressive behaviour. Human nose scores were a better predictor of the rank order of consumer perception, compared to skatole levels and to androstenone levels.
    Design of a Risk based Control System for Toxoplasma gondii in a pork supply chain
    Heres, L. ; Swanenburg, M. ; Koeijer, A.A. de; Boender, G.J. ; Oorburg, D. ; Urlings, B. ; Wisselink, H.J. - \ 2015
    In: Safepork 2015 Proceedings Book: Epidemiology and control of hazards in pork production chain. - - p. 81 - 84.
    Toxoplasma gondii is recognized as one of the major foodborne pathogens. The European Food Safety Authority (EFSA) concluded that T. gondii is one of the public health hazards in pigs to be covered within a modern meat inspection and advised to include serological testing of pigs and audits of pig farms to control T. gondii. A project is presented that develops a framework where this idea is practically implemented in a pork supply chain. The aim of the program is to reduce the contribution from the pork chain to the human toxoplasmosis disease burden. In the pilot at least one blood sample per batch at delivery at the slaughterhouse is tested with a Toxoplasma Elisa. With this screening 20 (1%) high risk herds were identified. These high risk farms and their controls, 2 per high risk farm, were followed up. More samples of risk farms and their controls were collected to get a better estimate of the within herd prevalence and to follow the development of serology over time. Additional MC-PCR was performed on hearts of pigs from these herds to confirm presence of infection, tissue cysts. Also farm assessments were done to verify the presence of risk factors at the identified farms. In the first farm where hearts were tested by PCR the presence of toxoplasma tissue cysts was shown. The results give insight in how risk based approaches with food chain information (FCI) for animals sent to slaughter could work, by substantiating how risk herds can be practically identified and which interventions are feasible. The results are discussed in the perspective of human health risks.
    Toxoplasma prevalence in Dutch slaughter pigs in the period 2012-2014
    Swanenburg, M. ; Boender, G.J. ; Heres, L. ; Koeijer, A.A. de; Wisselink, H.J. - \ 2015
    In: Safepork 2015 Conference: Epidemiology and control of hazards in pork production chain. - - p. 69 - 72.
    Identifying pig herds at risk for Toxoplasma gondii: prevalence and test characteristics
    Boender, G.J. ; Swanenburg, M. ; Koeijer, A.A. de; Heres, L. ; Giessen, J.W.B. van der; Wisselink, H.J. - \ 2015
    In: Proceedings: Apicomplexa in farm animals. - Edinburgh : Moredun Research Institute - p. 55 - 55.
    Risk-oriented animal health and food safety management : Risk-based innovations in food safety management
    Heres, L. ; Hiller, A. ; Schulze Althoff, G. ; Urlings, B. - \ 2014
    In: Quality and Risk Management in Agri-Food Chains / Petersen, B., Nüssel, M., Hamer, M., Wageningen Academic Publishers - ISBN 9789086862368 - p. 173 - 181.
    Farmer compliance - Health-status certification - Hygiene practices - Inspection strategies - Serological monitoring

    Secure animal health is of utmost importance for human health, animal welfare, resource efficiency and the effectiveness of livestock production. Food safety hazards, zoonotic diseases and the use of pharmaceuticals such as antibiotics have potential impacts on human health and wellbeing. Therefore, on-farm health and risk management is crucial to safeguard animal products as well as trade with livestock. Appropriate infrastructures for preventive health management to improve animal and human health and wellbeing are at the core of a 'one health' approach with provides a challenge at all levels of science and business. This chapter will inform you about: which structures have been established and which innovations have been made in riskoriented animal health and food safety management; how animal health management services and health status certification can be organised according to the AMOR principles; how and why on-farm biosecurity requirements have changed and how management support should be organised to foster a future one-health strategy.

    Effect van fokwaarde voor berengeur op het gedrag en berengeur van beren : Effect of genetic background for boar taint on the behaviour and boar taint of boars
    Peet-Schwering, C.M.C. van der; Troquet, L.M.P. ; Binnendijk, G.P. ; Vermeer, H.M. ; Riel, J.W. van; Fels, J.B. van der; Vogelzang, R.H. ; Knol, E.F. ; Heres, L. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 808) - 37
    varkenshouderij - beren (varkens) - berengeur - diergedrag - dierenwelzijn - fokwaarde - selectie - varkens - dierlijke productie - pig farming - boars - boar taint - animal behaviour - animal welfare - breeding value - selection - pigs - animal production
    In opdracht van het ministerie van Economische Zaken en het Productschap Vee en Vlees is op Varkens Innovatie Centrum (VIC) Sterksel en een praktijkbedrijf onderzocht of er een relatie is tussen ongewenst gedrag van beren en berengeur. Mocht deze relatie er zijn, dan wordt bij selectie op minder berengeur mogelijk ook geselecteerd op minder ongewenst gedrag van beren. Daarnaast is op 9 praktijkbedrijven nagegaan wat het effect is op berengeur bij de inzet van eindberen met een lage fokwaarde voor berengeur.
    Cost-effective allocation of resources for monitoring dioxins along the pork production chain
    Lascano Alcoser, V. ; Mourits, M.C.M. ; Fels-Klerx, H.J. van der; Heres, L. ; Velthuis, A.G.J. ; Hoogenboom, L.A.P. ; Oude Lansink, A.G.J.M. - \ 2014
    Food Research International 62 (2014). - ISSN 0963-9969 - p. 618 - 627.
    critical control points - dibenzo-p-dioxins - polychlorinated-biphenyls - contaminated feed - food-chain - incident - pcbs - pigs - perspective - pcdd/fs
    The pork chain has been seriously affected by dioxin incidents in recent decades. Hence, monitoring dioxins is crucial for detecting contaminations in the pork chain. This study aims to develop a decision support tool (optimization model) to determine cost-effective monitoring schemes for detecting and tracing a dioxin contamination over multiple control points along the pork production chain. The optimization model considers four control points (i.e. at the supplier of fatty feed ingredients, the feed mill, the slaughterhouse and the fat melting facility). It was applied to several hypothetical contamination scenarios involving contaminated animal fatty feed ingredients. The cost-effective allocation of resources for detecting and tracing the dioxin contamination from an integrated chain approach (i.e. considering all control points) focuses on monitoring at the feed mill, followed by the supplier of fatty feed ingredients and - to a lesser extent - by the slaughterhouse. The number of contaminated feed mills, the frequency of dioxin contaminations, the required level of effectiveness, and the cost of screening are main factors driving the total monitoring costs. Sharing the responsibility of monitoring dioxins within control points along the chain largely reduces the total monitoring costs. In each of the evaluated scenarios, the total costs of monitoring dioxins at individual control points are larger than the costs resulting from an optimal allocation of resources among all control points integrated in one overarching chain monitoring scheme. These results elicit the economic benefits of a chain approach to monitoring dioxins over an approach where each chain actor independently monitors dioxins. The developed model can be used by decision makers in the feed and food industry for determining optimal schemes for monitoring dioxins in the pork chain focusing on preventing specific contaminations
    Supply chain environmental management
    Grekova, E. ; Trienekens, J.H. ; Bremmers, H.J. ; Heres, L. ; Omta, S.W.F. - \ 2014
    In: Quality and risk management in agri-food chains / Petersen, Brigitte, Nüssel, Manfred, Hamer, Martin, Wageningen : Wageningen Academic Publishers - ISBN 9789086862368 - p. 168 - 172.
    Farm and management characteristics associated with boar taint
    Wagenberg, C.P.A. van; Snoek, H.M. ; Fels, J.B. van der; Peet-Schwering, C.M.C. van der; Vermeer, H.M. ; Heres, L. - \ 2013
    Animal 7 (2013)11. - ISSN 1751-7311 - p. 1841 - 1848.
    entire male pigs - subcutaneous fat - skatole - androstenone - behavior - performance - deposition - economy - weight - system
    Pig farms in the Netherlands producing boars have different levels of boar taint prevalence, as assessed by sensory evaluation with the human nose at the slaughter line. With a questionnaire to 152 Dutch pig producers (response rate 59%), farm and management characteristics were identified that are potentially associated with farm-level boar taint prevalence. Lower farm-level boar taint prevalence was associated with a smaller group size, a smaller pen surface per boar, newer housing equipment, not practicing restricted feeding in the last period before delivery, a longer fasting period before slaughter, a higher stocking weight and a lower fraction of boars from purebred dam line sows or from Pietrain terminal boars. These characteristics can be used to develop farm-level intervention strategies to control boar taint. More research effort is needed to establish causal relationships.
    Prevalence of Mycobacterium avium in Slaughter Pigs Based on Serological Monitoring Results and Bacteriological Validation
    Hiller, A. ; Oorburg, D. ; Wisselink, H.J. ; Solt-Smits, C.B. van; Urlings, H.A.P. ; Klein, G. ; Schulze Althoff, G. ; Heres, L. - \ 2013
    International Journal of Environmental Research and Public Health 10 (2013)9. - ISSN 1660-4601 - p. 4027 - 4038.
    swine lymph-nodes - rhodococcus-equi - nontuberculous mycobacteria - granulomatous lesions - subsp avium - infection - cattle - risk - epidemiology - supplement
    Mycobacterium avium (MA) is a potential food safety hazard in pigs. Blood samples of slaughtered pigs in the Netherlands and Germany were tested for the presence of MA antibodies to estimate the serological prevalence in the tested population. In the Dutch and German population 1.0% and 1.7% samples were positive, and 0.5% and 17.4% of the herds were at risk for having a MA infection respectively. The validity of the applied MA-ELISA was evaluated under field conditions. The specificity of the MA-ELISA was high (>98.4%). The average herd sensitivity was 18%. In the affected herds on average 50% of the animals were tested bacteriological positive for MA. It can be concluded that serological screening for the presence of MA antibodies is capable of identifying pig populations that are at risk for a MA infection.
    Approaches to reduce antibiotic resistance in the pork supply chain
    Heres, L. ; Dusseldorf, S. ; Oorburg, D. ; Urlings, H.A.P. - \ 2013
    In: Book of Abstracts of the 64th Annual Meeting of the European Federation of Animal Science, 26-30 August 2013, Nantes, France. - Wageningen : Wageningen Academic Publishers - ISBN 9789086862283 - p. 218 - 218.
    A quantitative approach towards a better understanding of the dynamics of Salmonella spp. in a pork slaughter-line
    Hoek, A.H.A.M. van; Jonge, R. de; Overbeek, W.M. van; Bouw, E.M. ; Pielaat, A. ; Smid, J.H. ; Malorny, B. ; Junker, E. ; Lofstrom, C. ; Pedersen, K. ; Aarts, H.J.M. ; Heres, L. - \ 2012
    International Journal of Food Microbiology 153 (2012)1-2. - ISSN 0168-1605 - p. 45 - 52.
    enterica serovar typhimurium - cross-contamination - carcasses - prevalence - excision - pigs - electrophoresis - identification - abattoirs - gauze
    Pork contributes significantly to the public health disease burden caused by Salmonella infections. During the slaughter process pig carcasses can become contaminated with Salmonella. Contamination at the slaughter-line is initiated by pigs carrying Salmonella on their skin or in their faeces. Another contamination route could be resident flora present on the slaughter equipment. To unravel the contribution of these two potential sources of Salmonella a quantitative study was conducted. Process equipment (belly openers and carcass splitters), faeces and carcasses (skin and cutting surfaces) along the slaughter-line were sampled at 11 sampling days spanning a period of 4 months. Most samples taken directly after killing were positive for Salmonella. On 96.6% of the skin samples Salmonella was identified, whereas a lower number of animals tested positive in their rectum (62.5%). The prevalence of Salmonella clearly declined on the carcasses at the re-work station, either on the cut section or on the skin of the carcass or both (35.9%). Throughout the sampling period of the slaughter-line the total number of Salmonella per animal was almost 2log lower at the re-work station in comparison to directly after slaughter. Seven different serovars were identified during the study with S. Derby (41%) and S. Typhimurium (29%) as the most prominent types. A recurring S. Rissen contamination of one of the carcass splitters indicated the presence of an endemic 'house flora' in the slaughterhouse studied. On many instances several serotypes per individual sample were found. The enumeration of Salmonella and the genotyping data gave unique insight in the dynamics of transmission of this pathogen in a slaughter-line. The data of the presented study support the hypothesis that resident flora on slaughter equipment was a relevant source for contamination of pork.
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