The objectives of this study were to investigate the coagulase gene polymorphism of Staphylococcus aureus isolates obtained from bovine mastitic milk and to determine the resistance of predominant and rare coagulase genotypes to bovine blood neutrophil bactericidal activities. A total of 453 isolates were collected from four countries: the Czech Republic, France, Korea and the United States. The isolates were subtyped into 40 types by restriction fragment length polymorphism (RFLP) of the coagulase gene. Twenty-three strains from predominant and rare genotypes were evaluated for their ability to resist neutrophil bactericidal activities. There were significant (P < 0.01) differences in the average percent neutrophil killing of the predominant (16.7%) and rare (39.7%) genotypes when bacteria were opsonized with antiserum. The results indicate that the profiles of coagulase genotype differ among geographic locations, and only a few genotypes prevail in each location. In addition, the predominant genotypes were more resistant to neutrophil bactericidal activities than rare genotypes.

101 samples of faeces, colonic mucosa and rectal swabs taken from 100 pigs (29 commercial herds) were cultivated on Trypticase Soy Agar with 5% of sheep blood, spectinomycin (200 mg/l), vancomycin (50 mg/l), rifampicin (12.5 mg/l) and colistin (12.5 mg/l). Plates were incubated in an anaerobic container at 37&deg;C for 5&ndash;7 days. 25 samples (10&nbsp;faeces, 15 scrapings of colonic mucosa) were examined by darkfield microscopy for the presence of spirochaetes. In 80&nbsp;samples (21 faeces, 31 rectal swabs, 28 scrapings of colonic mucosa) from diarrhoeic pigs 44 isolates of spirochaetes were identified by PCR method as Brachyspira hyodysenteriae. In 21 samples (20 rectal swabs, 1 scraping of colonic mucosa) taken from apparently healthy pigs in herds with swine dysentery were isolated weakly haemolytic spirochaetes: B. intermedia in 5 samples and phenotypic group III brachyspirae in 4 samples. Minimal inhibitory concentration (MIC) of tylosin, tiamulin and valnemulin was determined by the agar dilution method. To tylosin 16 out of 17 strains of B. hyodysenteriae were resistant (MIC 64 and 256 &micro;g/l), one strain was susceptible (MIC l &micro;g/ml). To tiamulin 17 out of 19 strains were susceptible (MIC from 0.016 to 0.25 &micro;g/ml), one strain was intermediately susceptible (MIC 2 &micro;g/ml) and one resistant (MIC 32 &micro;g/ml). To valnemulin 17 out of 19 strains were susceptible (MIC from 0.016 to 0.064 &micro;g/ml), one strain was intermediately susceptible (MIC2&micro;g/ml) and one was resistant (MIC 8 &micro;g/ml). Valnemulin resistant strain was also resistant to tiamulin.

Milk production of dairy cows in 14 herds was increased by 3 -8-32'l % by the administration of recombinant methionyl bovine somatotropin (bST) in a sustained-release vehicle at 14 d intervals at 40-94 d post partum. A greater response in multiparous than in primiparous cows was found in cows turned out to graze spring pasture. Administration of recombinant bST resulted in elevated plasma bST during the first 9 d after injection. Clinical characteristics such as respiration, heart rate and body temperature were unaffected by bST treatment, as were blood erythrocyte and leucocyte counts, haemoglobin concentrations and haematocrit values. Plasma levels of glucose, free fatty acids, urea and P, and serum alanine aminotransferase and aspartate aminotransferase were not affected by bST treatment, and acetone was not detected. No adverse effects of bST on general health, infection status of mammary glands, mastitis incidence and reproduction were found.Recombinant DNA technology has opened the way for the production of large quantities of polypeptides. As the use of recombinant bovine somatotropin (bST) could have an important impact on dairying, research on bST efficacy and safety in experimental and commercial dairy herds has been stimulated in many countries, including Czechoslovakia, where a high proportion of cows are in large state or cooperative farms. Diets for cows are based mainly on roughage and moderate amounts of concentrates, and herd management practices are often poor. A major current research interest is whether use of bST can significantly improve milk production under the conditions on Czech commercial dairy farms.The objective of the present investigation was to examine the effects of recombinant bST in a sustained-release vehicle on lactational performance, general health and mastitis incidence in dairy cows kept under different conditions in different parts of Czechoslovakia.

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