Effect of Se status on some haematological parameters in neonatal piglets.

Blood samples were taken from 74 1-3 day old piglets, the offspring of sows maintained during pregnancy on a commercial ration with 0.1 ppm of added Se as sodium selenite. At the time of blood sampling, all piglets were treated subcutaneously with 200 mg Fe+3 from iron dextran. Additional blood samples were taken 14 days after the iron treatment. Piglets with 14 day whole blood Se concentrations greater than 74.0 micrograms/l (n = 43) had significantly higher mean numbers of red blood cells than those with whole blood Se less than or equal to 74.0 micrograms/l (p = 0.016). The mean increase in erythrocyte numbers during the 14 day period was significantly higher in the higher than in the lower Se group (p = 0.007) as also in the piglets with plasma GSH-Px activity greater than 799 U/l at 1-3 days of age when compared to the piglets with the GSH-Px activity less than or equal to 799 U/l (p = 0.017).

Heat stable inhibitors produced in raw milk.

Twenty raw farm milk samples were tested for inhibitory substances before and after being kept at room temperature until the pH fell to less than 6.3 but greater than 6.2. The tests were done using the IDF-method and the commercial Thermocult method. In both methods B. stearothermophilus var. chalidolactis is used as the test organism. In two instances a thermostable inhibitor was produced with an inhibitory potential greater than 0.01 IU/ml penicillin standard. The IDF-method was found unsuitable for the study of relatively small concentrations of antibiotics or other chemotherapeutics in milk.

The testing of the antibiotic sensitivity of bacteria on an agar medium: The problem of a double zone of inhibition.

When the sensitivity of Micrococcus luteus ATTC9341 to streptomycin, erythromycin, oleandomycin and spiramycin was tested by an agar diffusion method using antibiotic impregnated filter paper disks on unbuffered Penassay Seed Agar two zones of inhibition were observed around the disks after an incubation period of 24 hours at 30 degrees C. The pH of the M. luteus seeded Penassay Seed Agar was measured before and after 24 hours incubation at 30 degrees C and found to be 6.6 and 8.7, respectively. When the Penassay Seed Agar was buffered to pH 6.1 and the sensitivity of the microbe to the antibiotics was tested as before no double zones of inhibition could be observed. The phenomenon of the double zones of inhibition may possibly be due to the pH increase of the medium from a relatively low level to the optimum range of activities of the antibiotics during the incubation period.

The occurrence of cyanide in certain smoked meat products.

Fifteen samples of smoked reindeer meat, two samples of smoked mutton from Iceland and five samples of smoked salamitype fermented sausage were analysed for their cyanide (CN) content by a steam distillation method. The mean cyanide content of the smoked reindeer meat was found to be 1.38 +/- 1.01 mg CH/kg, range 0.27--4.27 mg/kg. The two smoked mutton samples, contained 1.93 and 1.78 mg CN/kg and the mean cyanide content of the five Salami samples was found to be 0.19 +/- 0.13 mg CH/kg, range 0.06--0.40 mg/kg. The toxicological aspects of the findings are discussed, with special reference to the possible effects of nitrate and nitrite in the products.

Oxytetracycline residues in meat and kidney tissue after intramuscular or intramammary treatment as determined by a chemical-physical method and compared to a microbiological method.

Two adult cows and three calves were treated intramuscularly with an oxytetracycline (OTC) preparation. The dose was about 5 mg/kg. The animals were slaughtered eight days after the treatment and their kidneys and muscle samples were taken for analysis. Twelve cows were treated intramammarily with an OTC preparation 12 hours before slaughter. Six of the cows were treated in two udder quarters with a preparation containing 200 mg OTC chloride per dose; the other six were similarly treated in four quarters with four doses. When the kidneys of all the animals were studied for the presence of inhibitory substances using the official Finnish microbiological meat inspection method, all were found negative. The OTC concentration of the different tissue samples was determined by a chemical-physical method, based on thin-layer chromatography and on the UV-fluorescence of OTC. The muscle samples of the cows given OTC i.m. were negative except near the site of injection, where the concentrations were 4 mg and less than 0.5 mg (traces) per kg. The corresponding kidney concentrations of OTC were less than 0.5 and about 0.5 mg per kg respectively. All except one kidney sample of the calves given OTC i.m. were found to be negative. Traces of OTC (less than 0.5 mg/kg) were found in all but one kidney sample of the cows treated intramammarily with OTC. Traces of OTC were found in two muscle samples of the cows treated intramammarily with 2 X 200 mg OTC and in two muscle samples of the cows similarly treated with 4 X 200 mg OTC. All the other samples were negative. The authors stress the need for a change in the present Finnish directives on the use of antibiotics in food animals.

The problem of testing horse kidneys for the presence of antibiotics at meat inspection: how to avoid a false positive reaction.

When 33 horse kidneys were tested for the presence of inhibitory substances by the Bacillus subtilis BGA method at pH 8 and the Micrococcus luteus ATCC 9341 method, 24 were positive and 9 negative. The pH of the seeded M. luteus test medium changed from pH 6.6 before incubation to 8.7 after 24 hours incubation at 30 degrees C. When the same 33 kidneys were tested by the B. subtilis BGA method, medium pH 6, and 15 of them also by the M. luteus method using a medium buffered to pH 6, all were negative. The cadmium concentration of the 33 horse kidneys was found to be 70.17 +/- 81.28 mg/kg wet weight (m +/- s, range 10.40-355.67). The authors attributed the positive results to the presence of cadmium. The diffusion of cadmium from the horse kidney samples to the test media was found to differ at pH 6 and pH 8. It is recommended that the testing of horse kidney samples for the presence of antibiotics and chemoterapeutic substances be done at substrate pH 6 to avoid false positive reactions.

The detection of penicillin in buttermilk.

When 59 buttermilk samples were tested for the presence of antibiotics or chemostherapeutic substances by a method using the spores of Bacillus stearothermophilus var. chalidolactis all samples gave a positive reaction corresponding to about 0.01 IU penicillin per ml. When the buttermilk samples were diluted 1:1 (v/v) by a phosphate buffer, pH 6.8, only 2 were positive which were confirmed to contain penicillin. The mean pH of the unbuffered buttermilks was found to be 4.53 +/- 0.11 and when buffered 6.46 +/- 0.05. An in vitro addition of benzylpenicillin to buttermilk, to a concentration of 0.01 IU per ml, resulted in a significantly higher concentration of penicillin in the casein fraction than in the buttermilk or in the whey (Table I).

The occurrence of Bacillus cereus in Finnish dog food sausages; a microbiological and physiochemical survey.

A bacteriological survey of five brands of commercial dog food sausages showed that two of them were heavily contaminated with B. cereus. One of the two brands had a suspected association with food-poisoning incidents in dogs. In addition to B. cereus the other sausage brand was found to contain a high number of sulphite reducing anaerobes. B. cereus was detected in almost every raw material of the two brands of sausages. The pasteurization during manufacturing did not kill all the sporeforming organisms. The water activity of the sausages were equal to or more than 0.99 and pH in a range from 6.2 to 7.0. Methods of preventing the growth of microbes in the sausages after manufacturing are discussed.

Quantitative analysis of thiaminase activity in certain fish species.

Thiaminase I and II activity of Baltic herring, vendace, smelt and dace was measured. All four fish species were found to contain thiaminase activity. The amounts of thiaminase activity in mug of thiamine split per 100 g of fish tissue per hour at 37 degrees C were: in Baltic herring 115 +/- 60, in dace 11500 +/- 2050, in smelt 25 +/- 25 and in vendace 30+/- 15.