title: The effect of bovine diet on Salmonella survival in synthetic abomasal fluid.
abstract: OBJECTIVE
  To investigate the effect of diet on the survival of Salmonella in the bovine abomasum.
  
  
  RESULTS
  Five fistulated cows were randomly assigned to one of five diets denoted as: (i) 100% grass, (ii) grass + 5·3 kg DM concentrate, (iii) 100% grass silage, (iv) 100% hay and (v) maize/grass silage plus concentrates. Rumen fluid was harvested from each dietary treatment and inoculated with nonacid (NA) and acid-adapted (AA) 5-strain Salmonella cocktails. After 24-h incubation period, Salmonella were acid challenged to synthetic abomasum fluid (SAF, pH 2·5) for 5 h to determine their resistance to low pH. The study found that the volatile fatty acids composition and the pH profile of bovine rumen fluid were significantly altered (P <0·05) by some of the dietary treatments but not others. Regression analysis found that significantly higher numbers of acid-adapted Salmonella survived in SAF after incubation in rumen fluid from diets 1, 2 and 4, but fewer significant differences were found between diets for nonacid-adapted Salmonella. The results suggest that the acid-adapted cells were subjected to a higher level of cell injury than the nonadapted cells.
  
  
  CONCLUSIONS
  Pre-incubation in rumen fluid did influence the resistance of nonacid and acid-adapted Salmonella to SAF but it was dependant on the dietary treatment fed to the cows.
  
  
  CONCLUSIONS
  This study examined the use of diet, as a modulating factor to limit the bovine excretion of Salmonella with a view to providing a scientific basis for the design of dietary management controls in the future.
authors.affiliation: Teagasc, Ashtown Food Research Centre, Ashtown, Dublin, Ireland. mary.lenahan@teagasc.ie
authors.forename: M
authors.initials: M
authors.lastname: Lenahan
authors.forename: S
authors.initials: S
authors.lastname: Kelly
authors.forename: S
authors.initials: S
authors.lastname: Fanning
authors.forename: D J
authors.initials: DJ
authors.lastname: Bolton
mesh_terms: D000018:Abomasum / Q000378:metabolism / Q000382:microbiology*; D000143:Acids / Q000494:pharmacology; D000821:Animal Feed; D000818:Animals; D001826:Body Fluids / Q000378:metabolism / Q000382:microbiology; D002417:Cattle / Q000382:microbiology*; D002418:Cattle Diseases / Q000382:microbiology; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D005769:Gastrointestinal Motility; D006863:Hydrogen-Ion Concentration; D006109:Poaceae; D012475:Salmonella / Q000254:growth & development / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000382:microbiology; D012820:Silage
chemical_list: D000143:Acids; D005232:Fatty Acids, Volatile