Enumeration of Probiotic Bacilli Spores in Animal Feed: Interlaboratory Study

Fourteen out of 17 laboratories completed an interlaboratory study comparing 2 pretreatment protocols of feed samples containing authorized probiotic bacilli spores. Both methods used tryptone soy agar for enumeration. Pretreatment A involved preparation of a suspension of the feed sample in 50% ethanol. For pretreatment B, the sample was suspended in peptone salt solution and heated at 80°C for 10 min. Each laboratory analyzed 12 samples (6 per pretreatment), which represented duplicates of a high (109 colony-forming units [CFU]/g) and low (105 CFU/g) level of bacilli spores or a blank that contained vegetative probiotic bacteria only. For pretreatment A, the re-peatability relative standard deviation (RSDr) was 2.9% for the low level and 2.5% for the high. The reproducibility relative standard deviation (RSDR) values were 7.8 and 5.9%, respectively. Pretreatment B revealed RSDr values of 1.1 and 1.0%, and RSDR values of 5.8 and 3.4%, respectively. The heat treatment (pretreatment B) of feed samples had better precision data, resulted in higher viable bacilli counts, and was more effective in deactivating vegetative background flora. It is therefore recommended for adoption for official control purposes and for CEN and ISO standards.

Enumeration of Probiotic Pediococci in Animal Feed: Interlaboratory Study

An enumeration method to be used as official control under Council Directive 70/524/EEC for probiotic pediococci used as feed additives was validated for consideration for adoption as Comitée Européen de Normalisation (CEN) and ISO standards. Seventeen laboratories in 11 European countries carried out an interlaboratory study. A spread plate method following BS ISO 15214:1998 using 4 different agars [MRS, acidified MRS, MRS with triphenyl tetrazolium chloride (TTC), and a newly developed pediococci selective medium (PSM)] was validated. Precision data in terms of repeatability (r) and reproducibility (R) of the method for each medium using different feeding stuffs with a high and a low inoculation level were determined. Pediococci were present in the samples in mixtures with other probiotics. The enumeration of pediococci on all agars showedan RSDr value of 0.4–3.1% and an RSDR of 1.3–4.8%. MRS agar was preferred, followed by acidified MRS and MRS + TTC agar. All 4 media gave similar counts. Depending on the presence and concentration of other probiotic, such as enterococci, lactobacilli, and yeast, acidified MRS or MRS + TTC agar are recommended. The PSM was selective for pediococci and can be used if this species is present at a concentration more than 10-fold lower than other species that can grow on the MRS agars. The methodology with all 4 media is not applicable to mineral feed.

Assessment of a new selective chromogenic Bacillus cereus group plating medium and use of enterobacterial autoinducer of growth for cultural identification of Bacillus species

A new chromogenic Bacillus cereus group plating medium permits differentiation of pathogenic Bacillus species by colony morphology and color. Probiotic B. cereus mutants were distinguished from wild-type strains by their susceptibilities to penicillin G or cefazolin. The enterobacterial autoinducer increased the sensitivity and the speed of enrichment of B. cereus and B. anthracis spores in serum-supplemented minimal salts medium (based on the standard American Petroleum Institute medium) and buffered peptone water.

Enumeration of probiotic bacilli spores in animal feed: interlaboratory study

Fourteen out of 17 laboratories completed an interlaboratory study comparing 2 pretreatment protocols of feed samples containing authorized probiotic bacilli spores. Both methods used tryptone soy agar for enumeration. Pretreatment A involved preparation of a suspension of the feed sample in 50% ethanol. For pretreatment B, the sample was suspended in peptone salt solution and heated at 80 degrees C for 10 min. Each laboratory analyzed 12 samples (6 per pretreatment), which represented duplicates of a high (10(9) colony-forming units [CFU]/g) and low (10(5) CFU/g) level of bacilli spores or a blank that contained vegetative probiotic bacteria only. For pretreatment A, the repeatability relative standard deviation (RSD(r)) was 2.9% for the low level and 2.5% for the high. The reproducibility relative standard deviation (RSDR) values were 7.8 and 5.9%, respectively. Pretreatment B revealed RSD(r) values of 1.1 and 1.0%, and RSDR values of 5.8 and 3.4%, respectively. The heat treatment (pretreatment B) of feed samples had better precision data, resulted in higher viable bacilli counts, and was more effective in deactivating vegetative background flora. It is therefore recommended for adoption for official control purposes and for CEN and ISO standards.

[Not Available]

98 wheet samples harvested in 1998 from three different experimental plots in saxony where investigated on the species of fusarium and the mycotoxins DON, ZEA and nivalenol (NIV). Analysis of DON was done by fast-Elisa-test and HPLC-MS. There was a good correlation between the two methods but a tendency of higher values determined by Elisa. NIV was also determined by HPLC-MS and ZEA by HPLC-fluorescence.

[The effect of a Bordetella live vaccine on the occurrence and manifestation of atrophic rhinitis suum and the aerogenous infection burden in field strains of the agent]

A field study was carried out in a large scale unit for swine breeding and fattening with the object to influence the high morbidity rate of Atrophic Rhinitis and pneumonia with the help of a Bordetella live vaccine. The results show that it is possible to decrease the infectious pressure by B. bronchiseptica and to reduce the pathomorphological signs of Atrophic Rhinitis in consequence of the application of the live vaccine. The pathologic-anatomical investigations of nasal turbinates in immunized slaughtered fattening pigs show a significant lower morbidity concerning Atrophic Rhinitis and a higher percentage of pigs without changes at conchae nasales and septum nasi. We find also a lower contamination of the air with B. bronchiseptica field strains during vaccine application. The results also explain that a high infectious pressure by B. bronchiseptica and the possibility of communication between unvaccinated and vaccinated groups of pigs counteract a better efficiency of the vaccine. The decrease of the morbidity rate of Atrophic Rhinitis appears so much more important because toxicogenic Pasteurella multocida strains were isolated from nasal swabs of vaccinated pigs during the investigations. But these strains influenced the Atrophic Rhinitis frequency only accidentally. All results as a whole point out that in pig houses with a high animal density one has to pay more attention to virulent B. bronchiseptica strains than it was been done till now.