Tropical Beef: Is There an Axiomatic Basis to Define the Concept?

Cattle production in tropical regions has been estimated to account for just over half of cattle worldwide, yet it has not been demonstrated that sufficient similarities in the cattle exist to describe tropical cattle and, even less so, to characterize the meat from these animals. The aim of this review is to investigate the quality and nutrient composition of meat from cattle raised in the Tropics to determine if there is an axiomatic basis that would allow the definition of a concept of "tropical beef". Tropical beef is the meat obtained from cattle raised in tropical environments, the population of which remains largely uncharacterized. Production systems in the Tropics are highly diverse but converge on the use of indigenous and Bos indicus breeds or Bos indicus-influenced crossbreeds under pasture feeding regimes. While some systems allow cattle to be slaughtered at ≤2 years of age, most often animals are ≥3 years. These production systems generally produce lean, low-yielding carcasses and tough (>46 N), lean (≤3.6% intramuscular fat) meat with a macronutrient composition otherwise similar to beef from animals raised elsewhere (72-74% moisture and 20-24% protein). Fatty acid profiles depend on the breed and production systems, while mineral content is influenced by the environment. Although lean and tough, tropical beef is highly acceptable to the consumers it serves, is culturally and traditionally relevant and, in many countries, contributes to food security. Consolidating the findings from animal and meat science studies in the Tropics has allowed the demonstration of an axiomatic basis defining "tropical beef" as a concept.

Genomic surveillance of antimicrobial resistance shows cattle and poultry are a moderate source of multi-drug resistant non-typhoidal Salmonella in Mexico.

Multi-drug resistant (MDR) non-typhoidal Salmonella (NTS) is a public health concern globally. This study reports the phenotypic and genotypic antimicrobial resistance (AMR) profiles of NTS isolates from bovine lymph nodes (n = 48) and ground beef (n = 29). Furthermore, we compared genotypic AMR data of our isolates with those of publicly available NTS genomes from Mexico (n = 2400). The probability of finding MDR isolates was higher in ground beef than in lymph nodes:χ2 = 12.0, P = 0.0005. The most common resistant phenotypes involved tetracycline (40.3%), carbenicillin (26.0%), amoxicillin-clavulanic acid (20.8%), chloramphenicol (19.5%) and trimethoprim-sulfamethoxazole (16.9%), while more than 55% of the isolates showed decreased susceptibility to ciprofloxacin and 26% were MDR. Conversely, resistance to cephalosporins and carbapenems was infrequent (0-9%). MDR phenotypes were strongly associated with NTS serovar (χ2 = 24.5, P<0.0001), with Typhimurium accounting for 40% of MDR strains. Most of these (9/10), carried Salmonella genomic island 1, which harbors a class-1 integron with multiple AMR genes (aadA2, blaCARB-2, floR, sul1, tetG) that confer a penta-resistant phenotype. MDR phenotypes were also associated with mutations in the ramR gene (χ2 = 17.7, P<0.0001). Among public NTS isolates from Mexico, those from cattle and poultry had the highest proportion of MDR genotypes. Our results suggest that attaining significant improvements in AMR meat safety requires the identification and removal (or treatment) of product harboring MDR NTS, instead of screening for Salmonella spp. or for isolates showing resistance to individual antibiotics. In that sense, massive integration of whole genome sequencing (WGS) technologies in AMR surveillance provides the shortest path to accomplish these goals.

Genomic surveillance links livestock production with the emergence and spread of multi-drug resistant non-typhoidal Salmonella in Mexico.

Multi-drug resistant (MDR) non-typhoidal Salmonella (NTS) is increasingly common worldwide. While food animals are thought to contribute to the growing antimicrobial resistance (AMR) problem, limited data is documenting this relationship, especially in low and middle-income countries (LMIC). Herein, we aimed to assess the role of non-clinical NTS of bovine origin as reservoirs of AMR genes of human clinical significance. We evaluated the phenotypic and genotypic AMR profiles in a set of 44 bovine-associated NTS. For comparative purposes, we also included genotypic AMR data of additional isolates from Mexico (n = 1,067) that are publicly available. The most frequent AMR phenotypes in our isolates involved tetracycline (40/44), trimethoprim-sulfamethoxazole (26/44), chloramphenicol (19/44), ampicillin (18/44), streptomycin (16/44), and carbenicillin (13/44), while nearly 70% of the strains were MDR. These phenotypes were correlated with a widespread distribution of AMR genes (i.e. tetA, aadA, dfrA12, dfrA17, sul1, sul2, bla-TEM-1, blaCARB-2) against multiple antibiotic classes, with some of them contributed by plasmids and/or class-1 integrons. We observed different AMR genotypes for betalactams and tetracycline resistance, providing evidence of convergent evolution and adaptive AMR. The probability of MDR genotype occurrence was higher in meat-associated isolates than in those from other sources (odds ratio 11.2, 95% confidence interval 4.5-27.9, P < 0.0001). The study shows that beef cattle are a significant source of MDR NTS in Mexico, highlighting the role of animal production on the emergence and spread of MDR Salmonella in LMIC.

Whole genome sequencing reveals widespread distribution of typhoidal toxin genes and VirB/D4 plasmids in bovine-associated nontyphoidal Salmonella.

Nontyphoidal Salmonella (NTS) is a common pathogen in food-producing animals and a public health concern worldwide. Various NTS serovars may be present in apparently healthy animals. This could result in carcass contamination during the slaughter process leading to human exposure. While most genomic research has focused on Salmonella pathogenesis, little is known on the factors associated with subclinical infections and environmental persistence. We report here the widespread distribution of typhoidal toxin genes (i. e. the cdtB islet, hlyE, taiA), among NTS strains from a beef slaughter operation (n = 39) and from epidemiologically unconnected ground beef (n = 20). These genes were present in 76% of the strains, regardless of serovar, isolation source or geographical location. Moreover, strains that predominated in the slaughterhouse carry plasmid-borne type IV secretion systems (T4SS), which have been linked to persistent infections in numerous pathogens. Population genomics supports clonal dissemination of NTS along the food production chain, highlighting its role as reservoir of genetic variability in the environment. Overall, the study provides a thorough characterization of serovar diversity and genomic features of beef-associated NTS in Mexico. Furthermore, it reveals how common genetic factors could partially explain the emergence and persistence of certain NTS serovars in the beef industry.

[Antibiotic of resistence profile of Salmonella spp. serotypes isolated from retail beef in Mexico City]. / Perfil de resistencia a antibióticos de serotipos de Salmonella spp. aislados de carne de res molida en la Ciudad de México.

OBJECTIVE: To determine the serotype and antibiotic resistance profile of Salmonella spp. isolated from retail ground beef in Mexico City. MATERIALS AND METHODS: A total of 100 samples of ground beef were analyzed. The pathogen was isolated by conventional methods and confirmed by PCR (invA gene, 284 bp).The antibiotic resistance profile was determined by the Kirby-Bauer method while serotyping was performed according to the Kauffman-White scheme. RESULTS: We isolated a total of 19 strains of Lomita (6), Derby (4), Senftenberg (2), Javiana and Cannsttat (1) and undetermined (5) serotypes. The strains showed a high resistance rate to ampicillin (18/19), carbenicillin (16/19), tetracyclin (13/19), and trimethoprim-sulfamethoxazole (13/19). Multidrug resistance was observed in 14 isolates. CONCLUSIONS: Several Salmonella spp. serotypes of public health significance are circulating in ground beef sold in the major Mexican city. Some of these strains are multi-drug resistance.

Perfil de resistencia a antibióticos de serotipos de Salmonella spp. aislados de carne de res molida en la Ciudad de México / Antibiotic of resistence profile of Salmonella spp. serotypes isolated from retail beef in Mexico City

Resumen: Objetivo: Determinar el serotipo y perfil de resistencia a antibióticos de cepas de Salmonella spp. presentes en la carne de res que se expende en la capital mexicana. Material y métodos: Se analizaron 100 muestras de carne molida. Se aisló el patógeno por métodos convencionales y se confirmó por PCR (gen InvA, 284 pb). El perfil de resistencia a antibióticos se determinó por el método de Kirby-Bauer y la serotipificación por el esquema de Kauffman-White. Resultados: Se detectaron los serotipos Lomita (6), Derby (4), Senftenberg (2), Javiana y Cannsttat (1). Se observó alta resistencia a ampicilina (18/19), carbenicilina (16/19), tetraciclina (13/19) y trimetoprim-sulfametoxasol (13/19). Cinco cepas fueron no tipificables y 14 mostraron multirresistencia. Conclusiones: La carne de res que se vende en el principal centro de consumo del país está contaminada con serotipos de Salmonella spp. relevantes para la salud pública. Una importante proporción de éstos es resistente a múltiples antibióticos.

Abstract: Objective: To determine the serotype and antibiotic resistance profile of Salmonella spp. isolated from retail ground beef in Mexico City. Materials and methods: A total of 100 samples of ground beef were analyzed. The pathogen was isolated by conventional methods and confirmed by PCR (invA gene, 284 bp).The antibiotic resistance profile was determined by the Kirby-Bauer method while serotyping was performed according to the Kauffman-White scheme. Results: We isolated a total of 19 strains of Lomita (6), Derby (4), Senftenberg (2), Javiana and Cannsttat (1) and undetermined (5) serotypes. The strains showed a high resistance rate to ampicillin (18/19), carbenicillin (16/19), tetracyclin (13/19), and trimethoprim-sulfamethoxazole (13/19). Multidrug resistance was observed in 14 isolates. Conclusions: Several Salmonella spp. serotypes of public health significance are circulating in ground beef sold in the major Mexican city. Some of these strains are multi-drug resistance.

Exploratory survey at the mexican marketplace on pork muscles characteristics from USA and Mexico

Trends in variation of physical, chemical and sensory traits due to country of origin (COO) were evaluated for samples from United States of America (U.S.A.) and Mexico of three pork muscles, Rectus femoris (RF, n = 20 from each COO), Vastus medialis (VM, n = 20 from each COO), and Longissimus dorsi (LD, n = 10 from each COO) in two separate, small-scale, exploratory surveys conducted at Mexico City. Compositional, physical and chemical properties and consumer acceptability traits of these Mexican and U.S.A. pork samples were quite similar, though Mexican pork samples generally were more variable. LD samples from U.S.A. had greater (P<0.05) water-holding and emulsifying capacities whereas both RF and LD from U.S.A. required lower shear force (P<0.05) compared to Mexican counterparts. Ratings from consumers did not indicate preference for pork from any of the countries. Because of the limited number of observations for the samples surveyed these results are preliminary and may not adequately characterize the populations of each country, but they did reveal important trends for selected traits of Mexican and U.S.A. pork currently available at the local market.

Se evaluaron tendencias en la variación de características físico-químicas y sensoriales debidas al país de origen (PDO), de muestras mexicanas y estadounidenses (EUA) de tres músculos del cerdo: Rectus femoris (RF, n = 20 por PDO), Vastus medialis (VM, n = 20 por PDO), and Longissimus dorsi (LD, n = 10 por PDO) mediante dos encuestas exploratorias separadas, a baja escala, conducidas en la Ciudad de México. Los resultados mostraron que músculos porcinos de los dos orígenes tienen propiedades físicas, químicas y sensoriales muy similares, aunque las muestras mexicanas mostraron mayor variabilidad. Las muestras de LD de EUA tuvieron mayor (P<0,05) capacidad de retención de agua y emulsificación, y al igual que las de RF, requirieron menos fuerza de corte que las mexicanas (P<0,05). Los consumidores no pudieron detectar diferencias entre muestras de diferente origen. Debido al limitado número de observaciones en las muestras encuestadas, los resultados deben considerarse preliminares y si bien no permiten caracterizar adecuadamente las poblaciones de cada país, las mismas revelan tendencias importantes para los rasgos seleccionados de la carne de cerdo procedente de México y EUA disponibles actualmente en el mercado local.

Efecto del Cruzamiento, sexo y dieta en la composición química de la carne e ovinos Pelibuey con Rambouillet y Suffolk / Effect of crossbreeding with Suffolk and rambouillet, sex and diet on the chemical composition of Pelibuey lamb meat

El presente trabajo tuvo como objetivo principal evaluar la composición química de la carne de ovinos Pelibuey o Tabasco (P) y su cruza con Rambouillet (PR) y Suffolk (PS) a fin de identificar los cambios químicos reflejados en la calidad de la carne. Se utilizaron muestras de Longissimus dorsi de la media canal derecha de 30 ovinos que fueron alimentados con dos dietas diferentes, distribuyéndose en grupos de 5 animales para cada tratamiento. La dieta A consistía en heno de avena, ensilado de maíz, pasta de soya y sales minerales. La dieta B consistía en los mismos alimentos que la dieta A cambiando por bagazo de cítricos el ensilado de maíz. Se empleó el programa estadístico SAS, haciendo uso de un modelo de análisis factorial (3 x 2 x 2), método de Tukey y coeficiente de correlación de Pearson. Se evaluó la composición química (humedad, proteína, grasa, colágeno y cenizas) de la carne encontrándose diferencias significativas (P < 0.05) para la humedad, grasa y colágeno. En la composición química no influyó la sustitución de ensilado de maíz por bagazo de cítrico en la dieta. Las hembras presentaron carne más grasa y menos colágeno que los machos. Con base en los resultados obtenidos se concluye que la cruza de animales Pelibuey con Rambouillet y Suffolk mejora significativamente la composición química de la carne.

Tecnologías para la evaluación objetiva de las canales de animales de abasto / Technology for the objective evaluation of animal carcasses

El conocimiento de las diferencias entre las canales de animales de abasto ha tenido un impacto económico tan grande que en muchas ocasiones ha marcado cambios importantes en el curso de la industria cárnica internacional. Las canales de mayor valor en el mercado son las de mayor rendimiento y las de mejor calidad (definida esta última como las características sensoriales preferidas por los consumidores). En muchos países del mundo, el valor económico de la canal se determina a través de una evaluación de las características de la canal que proporcionan información sobre el rendimiento y la calidad. La predicción de la calidad y el rendimiento se pueden hacer de forma subjetiva (estimación por especialistas) u objetiva (con base en mediciones directas en las canales). Dentro de la metodología objetiva se han logrado grandes avances usando instrumentos destinados a estimar las características más significativas de la canal. La tecnología instrumental registra uno o más de los siguientes atributos: cantidad de grasa, cantidad de hueso y músculo. En este trabajo se revisan algunas de las tecnólogías más estudiadas a nivel internacional, entre las que se encuentran al ultrasonido, la conductividad eléctrica y las imágenes en video. La ventaja principal de estos instrumentos es que ofrecen la posibilidad de obtener medidas de las canales sin la necesidad de interpretación subjetiva del hombre; sin embargo, la principal desventaja se centra en la dificultad en su manejo y aplicación. Por estas razones, es indispensable que los instrumentos de medición empleados tengan la capacida de registrar medidas exactas, precisas y repetitivas de las características de la canal. La investigación de técnicas de evaluación de canales debe enfocarse al desarrollo de equipo de fácil manejo, que se pueda emplear en los rastros sin interrumpir la línea de sacrificio y que, además, proporcionen datos lo más exacto posible de las canales que evalúan