Thesis (MScAgric)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The world demand for animal proteins and profit-driven production has led to producing animal proteins intensively. Intensive pork production systems have traditionally had a poor image with the public, because these production systems are associated with environmental pollution. Currently, pigs are produced on highly specialised farms, and are fed concentrated (often imported) pig feed. The resulting higher production and higher animal densities contribute to an increased pollution of water, soil and air. The aim of this study is to determine the energy balance and emissions of three case studies, and to compare these results with their financial performance. The impacts will be recorded in the following impact categories: global warming potential (GWP), acidification potential (AP), eutrophication potential (EP) and Energy Use (EU). The case studies are three typical South African pig production facilities selected by the South African pork producer’s organisation (SAPPO). The production inputs, from the feed acquisition to the delivery of one kg of pig at the farm gate, were included. The three farms are located in different areas in South Africa, namely KwaZulu-Natal province (Case study 1), North-West province (Case study 2) and Western Cape province (Case study 3). The functional unit (FU) for this study is defined as 1 kg of South African pig (live-weight) at the farm gate. This study found that the GWP/FU of Case study 2 is 4 and 2 % higher than Case studies 1 and 3 respectively. The EP/FU of Case study 1 is 9 and 6 % higher than Case studies 2 and 3 respectively. The AP/FU of Case study 1 is 4 and 5 % higher than Case studies 2 and 3 respectively. The EU/FU of Case study 3 is 45 % and 16 % higher than Case studies 1 and 2 respectively. The major activities that contributed to the environmental impact categories were the slurry management activity, followed by electricity usage. The financial and environmental performance comparison did show deviations. Therefore, it is recommended that environmental and financial performance measurements be made, in order to create a true reflection of the impacts. The potential for improvement in financial and environmental performance proved to be significant in the productivity of the sow herd, as well as in the management of the piglets. The location of the production facility does not claim to hold have significant environmental or financial implications. Management of the emissions produced by piggeries can offset the impact of the piggery's location. / AFRIKAANSE OPSOMMING: Nie beskikbaar.

A suinocultura tem se fortalecido no mercado internacional devido ao aumento de consumo, importação e exportação de seus produtos e subprodutos; e principalmente pela necessidade mundial por alimentos, pelos avanços tecnológicos voltados à produção e comercialização, e pela valorização à qualidade dos produtos. Neste contexto, destaca-se a utilização da rastreabilidade aplicada na cadeia suína, como condição primordial para a comercialização nas exportações da carne suína brasileira. Dentre os processos de rastreabilidade, o acompanhamento “do campo à mesa” é um dos mais discutidos nos últimos anos, devido à amplitude de seu sistema, envolvendo a cadeia de suprimentos, a cadeia produtiva, o rastreamento de ativos e inspeções. O Brasil dispõe do terceiro maior rebanho suíno para abate do mundo, e faz uso de diversas tecnologias de rastreabilidade. Este trabalho descreve um estudo do frigorífico Doux localizado em Ana Rech, Caxias do Sul–RS, considerando a rastreabilidade sob um novo enfoque que engloba o caminho do suíno desde “o Laboratório à Mesa”, através da observação de diferenciais competitivos e ganhos produtivos que possam ser fornecidos através de informações rastreadas de carga genética, produtores e níveis de referência produtiva. A metodologia utilizada envolveu a pesquisa qualitativa, de caráter exploratório, através do desenvolvimento de um estudo de caso, utilizando-se ainda material documental e entrevistas individuais semi-estruturadas, considerando-se como embasamento teórico as abordagens relacionadas à rastreabilidade da carne suína, cadeia de suprimentos e cadeia produtiva suína. Como resultados esperados, prevê-se que a utilização da rastreabilidade “do Laboratório à Mesa” possibilitará à empresa, fazendo uso da união da genética e a sua gestão, bem como das especificidades dos diferentes mercados, melhorar o produto, atender determinadas características solicitadas por esses mercados, garantindo uma maior competitividade. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-13T13:18:19Z No. of bitstreams: 1 Dissertacao Andrea Rivieri dos Santos.pdf: 3521893 bytes, checksum: 25dde28dbfb42f01f1e249487449f315 (MD5) / Made available in DSpace on 2014-05-13T13:18:19Z (GMT). No. of bitstreams: 1 Dissertacao Andrea Rivieri dos Santos.pdf: 3521893 bytes, checksum: 25dde28dbfb42f01f1e249487449f315 (MD5) / The pig industry has become stronger in the international market due to increased consumption, import and export of their products and by-products especially the need for food of the world, through technological advances aimed at production and marketing, and the enhancement of product quality. In this context, we highlight the use of the traceability chain applied in swine, as a prime condition for commercialization in Brazil's pork exports. Among the processes of tracking, monitoring "from farm to fork" is one of the most discussed in recent years due to the breadth of your system, involving the supply chain, production chain, asset tracking and inspections. Brazil has the third largest herd of pigs for slaughter in the world, and makes use of several technologies for traceability. This paper describes a study of the company Doux located in Ana Rech, Caxias do Sul-RS, considering traceability in a new approach that encompasses the path of the pig from "Lab to the mouth", through the observation of competitive advantages and productivity gains that can be provided through the genetic information tracked, producers and production benchmarks. The methodology involved qualitative research, exploratory, by developing a case study, using documentary material and even individual semi-structured, considering as the theoretical framework approaches related to pork traceability, chain supplies and pork production chain. It is expected, as result, that the use of traceability "Lab to the mouth” will allow the company, by using the union of genetics and its management as well as the specificities of different markets, improvement of the product, meet certain characteristics required by these markets, ensuring greater competitiveness.

A suinocultura tem se fortalecido no mercado internacional devido ao aumento de consumo, importação e exportação de seus produtos e subprodutos; e principalmente pela necessidade mundial por alimentos, pelos avanços tecnológicos voltados à produção e comercialização, e pela valorização à qualidade dos produtos. Neste contexto, destaca-se a utilização da rastreabilidade aplicada na cadeia suína, como condição primordial para a comercialização nas exportações da carne suína brasileira. Dentre os processos de rastreabilidade, o acompanhamento “do campo à mesa” é um dos mais discutidos nos últimos anos, devido à amplitude de seu sistema, envolvendo a cadeia de suprimentos, a cadeia produtiva, o rastreamento de ativos e inspeções. O Brasil dispõe do terceiro maior rebanho suíno para abate do mundo, e faz uso de diversas tecnologias de rastreabilidade. Este trabalho descreve um estudo do frigorífico Doux localizado em Ana Rech, Caxias do Sul–RS, considerando a rastreabilidade sob um novo enfoque que engloba o caminho do suíno desde “o Laboratório à Mesa”, através da observação de diferenciais competitivos e ganhos produtivos que possam ser fornecidos através de informações rastreadas de carga genética, produtores e níveis de referência produtiva. A metodologia utilizada envolveu a pesquisa qualitativa, de caráter exploratório, através do desenvolvimento de um estudo de caso, utilizando-se ainda material documental e entrevistas individuais semi-estruturadas, considerando-se como embasamento teórico as abordagens relacionadas à rastreabilidade da carne suína, cadeia de suprimentos e cadeia produtiva suína. Como resultados esperados, prevê-se que a utilização da rastreabilidade “do Laboratório à Mesa” possibilitará à empresa, fazendo uso da união da genética e a sua gestão, bem como das especificidades dos diferentes mercados, melhorar o produto, atender determinadas características solicitadas por esses mercados, garantindo uma maior competitividade. / The pig industry has become stronger in the international market due to increased consumption, import and export of their products and by-products especially the need for food of the world, through technological advances aimed at production and marketing, and the enhancement of product quality. In this context, we highlight the use of the traceability chain applied in swine, as a prime condition for commercialization in Brazil's pork exports. Among the processes of tracking, monitoring "from farm to fork" is one of the most discussed in recent years due to the breadth of your system, involving the supply chain, production chain, asset tracking and inspections. Brazil has the third largest herd of pigs for slaughter in the world, and makes use of several technologies for traceability. This paper describes a study of the company Doux located in Ana Rech, Caxias do Sul-RS, considering traceability in a new approach that encompasses the path of the pig from "Lab to the mouth", through the observation of competitive advantages and productivity gains that can be provided through the genetic information tracked, producers and production benchmarks. The methodology involved qualitative research, exploratory, by developing a case study, using documentary material and even individual semi-structured, considering as the theoretical framework approaches related to pork traceability, chain supplies and pork production chain. It is expected, as result, that the use of traceability "Lab to the mouth” will allow the company, by using the union of genetics and its management as well as the specificities of different markets, improvement of the product, meet certain characteristics required by these markets, ensuring greater competitiveness.

Doctor of Philosophy / Department of Animal Sciences and Industry / Jim L. Nelssen / Eleven-thousand one-hundred eighty-five pigs were used in 11 experiments to determine effects of birth-weight, feeder design, and dietary astaxanthin (AX) and ractopamine HCl (RAC) on growth, carcass, and pork quality characteristics of pigs. Also, data from 27 experiments were used in meta-analyses to improve prediction of pork fat iodine value (IV). In Exp. 1, increased birth-weight resulted in greater (quadratic, P < 0.05) pre-weaning survivability, ADG, final BW, and likelihood of achieving full-value market at 181-d of age. In Exp. 2, 3, 4, 6, 7, and 8, pigs using the wet-dry feeder (WD) had greater (P < 0.05) ADG, ADFI, and final BW than those using the conventional dry feeder (CD). Pigs using WD had poorer (P < 0.05) G:F in Exp. 3 and 4, and increased (P < 0.05) HCW and backfat depth in Exp. 3, 4, 6, and 7, compared to pigs fed using CD. In Exp. 5, pigs using WD from 19 to 38 kg had decreased (P < 0.02) ADFI and better G:F than pigs using CD. Increased feeder opening of WD increased (P < 0.05) ADG, ADFI, and final BW in Exp. 5, 6, and 7; as well as HCW and backfat depth in Exp. 6 and 7. Reducing WD opening at 28- and 56-d in Exp. 7 decreased (P < 0.05) ADG, ADFI, and backfat depth. Different openings of CD had little effect on performance in Exp. 5 and 6. In Exp. 8, changing water-source of WD to a separate location during late-finishing reduced (P < 0.05) overall ADG, ADFI, and final BW. Limited responses to AX were observed in Exp. 9, 10, and 11, but ADG, G:F, final BW, HCW, and fat-free lean were improved (P < 0.05) for pigs fed RAC in Exp. 10 and 11. Total color change during retail display of LM chops for gilts and pigs fed RAC was reduced (P < 0.05) in Exp. 10 and 11, indicating their color shelf-life improved. In the meta-analyses, models using dietary PUFA with ADG, BW, or backfat depth improved the fat IV prediction from R2 = 0.45 to R2 = 0.90.

Call number: LD2668 .T4 1985 C475 / Master of Science

Master of Science / Department of Animal Sciences and Industry / Terry A. Houser / The objectives of this study were to determine the impact of 0 and 20% dried distillers grains with soluble (DDGS) and increasing levels of glycerol (0, 2.5 and 5%) in grow-finishing rations on bacon quality and to determine the relationship between belly firmness and slicing yield for commercially produced bacon. A total of 84 barrows (PIC, initially 31.03 kg) were fed corn-soybean meal-based diets organized in a 2 x 3 factorial with primary effects of DDGS (0 or 20%) and glycerol (0, 2.5, or 5%) as fed. Belly length was measured from flank end to blade end. Belly thickness was measured at eight locations evenly spaced around the perimeter of the belly. Belly firmness was measured by centering bellies perpendicularly (skin side up and skin side down) over a stainless steel smokestick and measuring the flex between the edges on the ventral and dorsal edges of the belly. Bellies were injected at 12% of the skinned belly weight resulting in a final concentration of 1.74% salt, 0.5% sugar, 0.3% sodium phosphate, 120 ppm sodium nitrite, and 500 ppm sodium erythorbate in the bellies. Bellies were cooked to an internal temperature of 53oC, chilled, pressed and sliced for evaluation. Belly slice yield was calculated by determining the yield of #1 type bacon slices. Proximate analysis and fatty acid analysis were evaluated by taking every 10th bacon slice beginning from the caudal end to make a composite sample for each belly. Iodine value was calculated using the resulting fatty acid content results. Twenty bacon slices were removed from the belly one-third the length of the belly from the cranial end for sensory analysis and cooking yields. Sensory characteristics were evaluated on an 8-point scale for brittleness, bacon flavor intensity, saltiness and off-flavor. There were no significant DDGS x glycerol interactions on any parameters measured (P > 0.08). Inclusion of 20% DDGS in pig diets decreased belly firmness (P < 0.04) as measured by the belly flop fat side down method. Twenty percent DDGS decreased the percentage of myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, vaccenic acid, total saturated fatty acids, and total monounsaturated fatty acids (P < 0.01). In contrast, 20% DDGS increased the percentage of linoleic acid, α-linolenic acid, eicosadienoic acid, total polyunsaturated fatty acids and decreased unsaturated: saturated fatty acid ratios, polyunsaturated: saturated fatty acid ratios, and iodine values (P < 0.01). Statistical correlation analysis of belly processing characteristics showed that by increasing belly weight there will be an increase in smokehouse yields (R = 0.81), increasing smokehouse yields will increase slice yield (R = 0.71), increasing belly thickness results in firmer bellies (R = 0.94) and increasing belly firmness will increase slice yields (R = 0.60). Fatty acid content did not correlate with any belly processing characteristic (R < 0.50). Iodine values were highly correlated with Total MUFA (R = 0.83) Total PUFA (R = 0.79), Total TFA (R = 0.75), and UFA: SFA ratio, and PUFA: SFA ratios (R = 0.83). The inclusion of 0, 2.5 and 5% glycerol in swine diets did not affect any measured parameters in this study. In conclusion, feeding DDGS at a level of 20% decreased belly firmness and changed the fatty acid profile; however, it did not affect belly processing or sensory characteristics. Glycerol fed at 2.5 or 5.0% did not affect belly quality, fatty acid profile, or sensory characteristics of bacon.

Food safety scares affect consumption behavior, and food safety and animal health issues are increasingly impacting international agricultural trade. Foot-and-mouth disease (FMD) is a highly contagious viral-type disease, and has raised not only the concerns of animal health issue but also food safety issue. Over 58 countries in the world have experienced FMD outbreaks, and pork exports and imports among these countries are largely impacted. This dissertation focuses on how global pork trade is affected by FMD. This dissertation consists of three parts: first, this study specifically focuses on the market of U.S. pork exports. Results show that disease-affected pork importers are potential traders with the U.S., and only importing countries with a vaccination policy are more likely to increase pork imports from the U.S. rather than those importers with a slaughter policy. Second, a further investigation focuses basic hypothesis on import demand of FMD-affected importers by using a gravity model with fixed-effects to show how pork trade is affected by FMD among 186 countries. Results confirm that pork export falls when an exporting country develops FMD. Exporters with a vaccination policy have larger negative impacts than those with a slaughter policy. Further, pork importers that develop FMD and institute a slaughter policy will import more pork, but importers with a vaccination policy import the same level of pork. Third, the findings of part one and two reveal that FMD-free pork exporters face different market opportunities when pork importers have FMD outbreaks. Hence, four major FMD-free pork exporters, such as Canada, U.S., Germany, and Spain, are further investigated. Results confirm that the impacts of foreign FMD have altered pork exporters differently. Germany has gained the most exports during foreign FMD outbreaks in pork importers; the U.S. is second; Spain is third; and Canada is fourth. In sum, this dissertation contributes to the literature of gravity model when endogeneity and heteroskedasticity may coexist, when an extremely large number of zero observations are included, when single commodity for one specific exporter is analyzed, when a spatial econometric approach is compared, and when pork export market has been altered by foreign FMD outbreaks.

Atualmente, a campilobacteriose representa uma importante zoonose tanto em países desenvolvidos quanto em países em desenvolvimento. No Brasil, vários estudos relatam a alta frequência de suínos eliminando o agente nas fezes, porém, a contaminação da carne suína comercializada tem sido pouco avaliada, principalmente no que diz respeito à presença de Campylobacter spp. A incidência deste agente em cortes de carne de aves é mais descrita, porém ainda faltam estudos que esclareçam a epidemiologia da doença. Os objetivos principais do presente estudo foram avaliar a presença de Campylobacter spp. em cortes de carne de frangos e suínos vendidos em mercados municipais, açougues e mercados de pequeno porte distribuídos nas cinco regiões do município de São Paulo. Das 115 amostras de origem suína avaliadas sete se mostraram positivas ao isolamento de Campylobacter coli e, das 105 amostras de carne de frango, 31 estavam contaminadas por Campylobacter jejuni ou Campylobacter coli. Dentre as 38 amostras de carne de frango e suíno positivas foram selecionadas 60 estirpes, as quais foram caracterizadas quanto à espécie, utilizando a reação em cadeia pela polimerase e a espectrometria de massa MALDI-TOF, foram ainda avaliadas quanto ao perfil de resistência a antimicrobianos e foram submetidas a genotipagem pelo polimorfismo de comprimento de fragmentos amplificados (AFLP). A partir dos resultados obtidos seis estirpes foram selecionadas para realização do sequenciamento do genoma completo e a partir da análise dos genomas foram identificados os STs, os genes de resistência e genes de virulência. / Currently, Campylobacteriosis represents an important zoonosis in both developed and developing countries. In Brazil, several studies report a high frequency of pigs excreting the agent in the feces, but the contamination of marketed pork has been insufficiently evaluated, especially with regard to the presence of Campylobacter spp. The incidence of this agent in cuts of poultry meat is more detailed; however, there are still studies lacking that clarify the epidemiology of the disease. The main aims of the present study were to evaluate the presence of Campylobacter spp. in chicken and pork cuts sold in municipal markets, butchers and small markets distributed in the five regions of the city of São Paulo. Of the 115 pork samples evaluated, seven were Campylobacter coli isolation positive and 31 of the 105 chicken samples were contaminated with Campylobacter jejuni or Campylobacter coli. Of the 38 chicken and pork positive samples, 60 strains were selected, which were characterized by species using polymerase chain reaction and MALDI-TOF mass spectrometry. They were also assessed for antimicrobial resistance profile and were genotyped by amplified fragment length polymorphism (AFLP). From the results obtained six strains were selected to carry out the complete genome sequencing and from the genome analysis the STs, the resistance genes and the virulence genes were identified.

Atualmente, a salmonelose representa uma das zoonoses de maior importância em Saúde Pública no mundo, em razão da alta endemicidade, mortalidade, e dificuldade do seu controle. No município de São Paulo, é possível encontrar diferentes realidades no que se diz respeito às boas práticas de produção e ao controle de qualidade dos produtos de origem animal, principalmente quando se considera os pontos de venda direta ao consumidor. Os objetivos do presente estudo foram avaliar a presença de Salmonella entérica em cortes de carne suína vendidos em mercados municipais, açougues e mercados de pequeno porte distribuídos nas cinco regiões do município de São Paulo. As estirpes isoladas foram caracterizadas quanto ao sorotipo, perfil de resistência a antimicrobianos, perfil genotípico através da eletroforese em campo pulsado (PFGE) e do polimorfismo do comprimento de fragmentos amplificados (AFLP). A partir dos 394 cortes de carne avaliados 6% foram positivos para o isolamento de S. enterica. Dentre os 111 estabelecimentos examinados, 14,4% apresentaram pelo menos um corte de carne positivo. Dentre as 60 estirpes selecionadas para caracterização, os sorotipos identificados foram Typhimurium (33,3%), London (26,7%), Brandenburg (10,0%), Schwaezengrund (8,3%), Derby (8,3%), Infantis (6,7%), Javiana (6,7%). A determinação da concentração inibitória mínima indicou as seguintes frequências de resistência antimicrobiana: azitromicina (100%), sulfametoxazol (98,3%), ampicilina (50%), cloranfenicol (41,7%), tetraciclina (40%), ácido nalidixico (21,7%), gentamicina (16,7%), trimetoprim (15%) e ciprofloxacina (5%). Todos os isolados foram sensíveis à cefotaxima, ceftazidima, meropenem e tigeciclina. Multirresistência foi identificada em 58,3% das estirpes avaliadas. A caracterização das estirpes pela PFGE e pelo AFLP revelou uma tendência a agrupar os isolados de acordo com a origem e com os sorotipos. A partir do sequenciamento do genoma de 11 estirpes foi possível identificar os STs, a presença de genes de resistência e de ilhas de patogenicidade. Os dados obtidos foram discutidos frente aos perfis descritos de estirpes de Salmonella entérica oriundas de criações de suínos e casos de infecção alimentar relatados no país e no exterior. / Currently, salmonellosis represents one of the most important zoonoses in Public Health in the world, due to the high endemicity, mortality, and difficulty of its control. In the city of São Paulo, it is possible to find different realities regarding good production practices and quality control of animal products, especially when considering the points of direct sales to the consumer. The objectives of the present study were to evaluate the presence of Salmonella enterica in pork cuts sold in municipal markets, butchers and small markets distributed in the five regions of the city of São Paulo. Isolated strains were characterized for serotype, antimicrobial resistance profile, genotypic profile through pulsed field electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP). From the 394 meat cuts evaluated 6% were positive for isolation of S. enterica. Among the 111 establishments examined, 14.4% had at least one positive meat cut. Among the 60 strains selected for characterization, the identified serotypes were Typhimurium (33.3%), London (26.7%), Brandenburg (10.0%), Schwaezengrund (8.3%), Derby (8.3%), Infantis (6.7%) andJaviana (6.7%). Determination of the minimum inhibitory concentration indicated the following frequencies of antimicrobial resistance: azithromycin (100%), sulfamethoxazole (98.3%), ampicillin (50%), chloramphenicol (41.7%), tetracycline (40%), nalidixic acid (21.7%), gentamicin (16.7%), trimethoprim (15%) and ciprofloxacin (5%). All isolates were sensitive to cefotaxime, ceftazidime, meropenem and tigecycline. Multiresistance was identified in 58.3% of the strains evaluated. Characterization of the strains by PFGE and AFLP revealed a tendency to group the isolates according to the origin and the serotypes. From the genome sequencing of 11 strains it was possible to identify STs, presence of resistance genes and pathogenicityislands. The data obtained were discussed in relation to the described profiles of S. enterica strains from pig herds and cases of food infection reported in the country and abroad.

Introdução - A bactéria Listeria monocytogenes é um agente zoonótico transmitido, principalmente, por alimentos. Dentre as fontes de contaminação, destacam-se os produtos de origem láctea, carnes e embutidos, além dos ambientes da indústria de processamento alimentício. Na última década, foram detectadas cepas de L. monocytogenes e L. innocua, em ambiente de frigoríficos e alimento. Estas apresentavam variação na intensidade da virulência para células eucarióticas decorrente de mutações nos genes de virulência. Esta alteração em ambas as espécies, e o relato de um caso fatal de listeriose humana ocasionada por L. innocua atípica demandam atenção, pois apresentam maior risco à saúde da população exposta a estes ambientes e alimentos tornando-se, portanto, uma importante questão de saúde pública. Objetivo - Pesquisar genes de virulência em cepas de L. monocytogenes e L. innocua, isoladas em pontos da linha de abate suíno e do comércio de carne no Estado de São Paulo. Material e Métodos Foram estudadas 40 cepas, dentre estas, isolados de L. monocytogenes e L. innocua com atividade hemolítica atípica. Foram realizados testes de atividade hemolítica e produção de fosfolipase A para caracterização dos isolados. A detecção dos genes de virulência foi realizada através da reação em cadeia pela polimerase (PCR). Para confirmação das sequências amplificadas e a análise das mesmas, os fragmentos obtidos foram sequenciados. A identificação molecular das espécies foi realizada por análise filogenética dos genes prs e 16S rRNA. Resultados Dos 40 isolados, cinco de L. monocytogenes e sete de L. innocua apresentaram atividade hemolítica atípica, sendo que nestes últimos também foi observado halo atípico no meio ALOA. As cepas de L. monocytogenes foram positivas para a detecção de todos os genes de virulência estudados. Dois dos isolados atípicos de L. innocua também foram positivos para todos os genes e os outros cinco foram positivos para hly, plcA e inlC. Foram detectadas mutações nas proteínas InlC, InlB, InlA, PI-PLC, PC-PLC e PrfA, nas cepas atípicas, que resultaram em alterações nas suas estruturas secundárias que podem explicar o fenótipo desses isolados. A confirmação de espécie apenas foi alcançada com a análise filogenética do 16S rRNA. Conclusões A partir desses resultados, foi proposta a utilização dos genes prfA, plcB e inlB, como forma de triagem, para diferenciar as espécies L. monocytogenes e L. innocua, de modo a complementar os testes fenotípicos / Introduction - The bacterium Listeria monocytogenes is a zoonotic agent transmitted, mainly, by food. Among the sources of contamination, stands out dairy products, meat and the environments of food processing industry. In the last decade, strains of L. monocytogenes and L. innocua have been detected in food and slaughterhouses environment. These presented variation in the intensity of virulence to eukaryotic cells due to mutations in the virulence genes. These changes in both species, and the report of a fatal case of human listeriosis caused by atypical L. innocua demand attention, because they present greater risk to the health of the population exposed to these environments and food and, therefore, it is an important public health issue. Objective - To search for the virulence genes in strains of L. monocytogenes and L. innocua isolated in points of swine slaughter line and meat trade in Sao Paulo State. Material and Methods 40 strains were studied, among these, isolates of L. monocytogenes and L. innocua with atypical hemolytic activity. Tests of hemolytic activity and production of phospholipase A were performed for isolates characterization. The detection of virulence genes was performed through polymerase chain reaction (PCR). For confirmation of the amplified sequences and analysis of the same, the obtained fragments were sequenced. The molecular identification of species was performed by phylogenetic analysis of 16S rRNA and prs genes. Results - Of the 40 isolates, five L. monocytogenes and seven L. innocua showed atypical hemolytic activity, and in these last ones an atypical halo was also observed in ALOA medium. The L. monocytogenes strains were positive for detection of all virulence genes studied. Two atypical L. innocua isolates were also positive for all genes and the other five were positive for hly, plcA and inlC. Mutations in InlC, InlB, InlA, PI-PLC, PC-PLC and PrfA proteins were detected, in the atypical strains, which resulted in changes in their secondary structures that may explain the isolates phenotype. Species confirmation was achieved only with phylogenetic analysis of 16S rRNA. Conclusions - From these results, it was proposed the use of prfA, plcB and inlB genes as a way of screening, to differentiate the species L. monocytogenes and L. innocua, in order to complement the phenotypic tests