RESUMO
Escherichia coli O157 is a foodborne pathogen that can be transmitted by contaminated ground beef and is shed naturally in cattle feces. Recent reports indicated that feeding distillers' grains (DG) to cattle increased fecal shedding and prevalence of E. coli O157. In Minnesota, feeding DG with solubles (DGS) to livestock became widespread within the last 10 years, but there is no report about the prevalence of E. coli O157 in beef cattle in this state. This study was undertaken to survey the fecal prevalence of E. coli O157 in cattle fed diets containing DG and its association with environmental conditions and management practices. Fecal samples were collected from three feedlots during a 1-year period. All animals in those feedlots were fed different DGS levels. E. coli O157 presence was determined using a combination of enrichment, immunomagnetic separation, plating onto sorbitol MacConkey agar, and confirmation of isolates by immunoassay and multiplex virulence genes polymerase chain reaction analysis. Overall, E. coli O157 was confirmed in 9.7% of samples. Prevalence during summer was 30% and declined to less than 10% the rest of the year. In animals grouped by dietary DGS concentration, no significant difference in prevalence (12.0 and 5.5%) was detected between the low and the high average groups (less and more than 20%). Previous feeding of DGS before arriving to the feedlot also had no influence on fecal prevalence. The presence of several interacting variables, uncontrolled in a real-life feedlot environment, was the likely reason for our observation and suggested that at the levels studied, DGS had no effect on the STEC O157 prevalence in cattle populations.
Assuntos
Ração Animal , Criação de Animais Domésticos/métodos , Bovinos/microbiologia , Grão Comestível , Escherichia coli O157/crescimento & desenvolvimento , Resíduos , Bebidas Alcoólicas/economia , Ração Animal/efeitos adversos , Ração Animal/economia , Criação de Animais Domésticos/economia , Animais , Derrame de Bactérias , Biocombustíveis/economia , Destilação , Grão Comestível/efeitos adversos , Escherichia coli O157/classificação , Escherichia coli O157/isolamento & purificação , Escherichia coli O157/metabolismo , Etanol/metabolismo , Fezes/microbiologia , Feminino , Fermentação , Indústria de Processamento de Alimentos/economia , Masculino , Indústria de Embalagem de Carne/economia , Indústria de Embalagem de Carne/métodos , Minnesota , Tipagem Molecular , Estações do Ano , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Resíduos/efeitos adversos , Resíduos/economiaRESUMO
Porcine circovirus type 2b (PCV2b) causes PCV-associated disease in pigs. This study was conducted to investigate the effect of temperature on the survival of PCV2b in fresh pork. Several pieces of longissimus dorsi muscle were injected with 100 µL of a suspension containing 10(5.2) TCID50 (50% tissue culture infective doses) of the virus. Virus-inoculated pieces of pork were stored at 25 °C, 4 °C and -20 °C and tested for the presence of infectious virus after different times of storage. PCV2b was found to survive in fresh pork for up to 2 days post inoculation (dpi) at room temperature, for 6 dpi at 4 °C and for up to 30 dpi at -20 °C indicating that the survival of PCV2b in fresh pork depends on temperature of storage.
