title: A collaborative study of a method for enumeration of probiotic enterococci in animal feed.
abstract: OBJECTIVE
  Validation of an enumeration method to be used as an official control method in the framework of Council Directive 70/524/EEC for probiotic enterococci used as feed additives.
  
  
  RESULTS
  Twenty laboratories in 12 European countries carried out a collaborative study. A plate count method using bile esculin azide (BEA) agar was used. Precision data in terms of repeatability (r) and reproducibility (R) of the method using different feeding stuffs and three inoculation levels were determined. Enterococci were present in the samples as a single component or in mixtures with other probiotic feed additives. The enumeration of enterococci on BEA agar showed a relative standard deviation (RSD)r of 1.5-3.6% and an RSD(R) between 2.9 and 7.4%. BEA agar was selective for enterococci in the presence of other probiotic micro-organisms such as pediococci, lactobacilli and yeast.
  
  
  CONCLUSIONS
  For routine analysis of viable enterococci concentrations in feeding stuffs, the use of BEA is recommended. This methodology is not applicable for mineral feeds.
  
  
  CONCLUSIONS
  An official control method for enumeration of authorized probiotic enterococci in feeding stuffs was validated. The results are intended for consideration for adoption as CEN and ISO standards.
authors.affiliation: Central Science Laboratory, Department for Environment, Food and Rural Affairs, York, UK. r.leuschner@csl.gov.uk
authors.forename: R G K
authors.initials: RG
authors.lastname: Leuschner
authors.forename: J
authors.initials: J
authors.lastname: Bew
authors.forename: K J
authors.initials: KJ
authors.lastname: Domig
authors.forename: W
authors.initials: W
authors.lastname: Kneifel
mesh_terms: D000821:Animal Feed / Q000382:microbiology*; D015169:Colony Count, Microbial / Q000379:methods*; D016983:Enterococcus / Q000254:growth & development*; D007778:Lactobacillus / Q000145:classification / Q000254:growth & development; D019936:Probiotics / Q000032:analysis*; D015203:Reproducibility of Results; D015003:Yeasts / Q000254:growth & development