Acta Veterinaria Scandinavica 2006, 48:22 http://www.actavetscand.com/content/48/1/22 mean SCC was ≥ 1,000,000/ml. Staphylococcal infec- tions, S. aureus and CNS, were as common in this study as in the study of Aasmäe et al. [3]. Contagious bacteria (eg. S. aureus, C. bovis and S. agalac- tiae) caused most of the infections in this study. These infections are usually spread from cow to cow at milking if the milking hygiene is not good enough. Therefore it is likely that the mastitis situation could be improved by improving milking procedures and hygiene. It is known that milking procedures and practices followed by milkers strongly influence the prevalence of mastitis in herds as well as the overall milk quality [8,15]. In some of the herds, a milker used more than three milking units simul- taneously, which can further impair the milking routine. However, milking procedures such as teat cleaning, udder preparation before milking, and overmilking were not observed in this study. The farms in this study had clearly defined, separate work tasks between personnel. Typically, it was only milkers who did the milking. Each milker had his/her own group of about 60–65 cows. The employees' job descriptions were of the rigid kind and did not contribute to the pre- vention of mastitis. In the few cases where women owners participated in the milking, the prevalence of mastitis was lowest. This finding could be in line with the finding of Barnouin et al., according to which a herdsman precise in his techniques was associated with the herd having low SCC [16]. Owners probably are more motivated to main- tain precise milking techniques than hired personnel and therefore a clearer motivation-based approach for the responsibilities of employees and supervisors would improve the mastitis situation. The finding that peat was associated with higher mastitis prevalence could be due to difficulties in keeping animals clean. This association has not been observed in some other studies. Hovinen et. al. observed that bedding mate- rial (peat, sawdust or straw) on the teat was cleaned almost completely in automatic milking herds, and Peltola found out that peat litter had no effect on the state of health of the animals or on the quality of the milk [17,18]. There were also other deficiences in housing conditions and milking machines, which should be corrected. In many herds, for instance, the stalls were too short for the cows of today. The milk claws were too small (less than 150 ml) in some herds [19]. Even though statistical anal- ysis did not point out specific risk factors, such as milking claws being too small or the infrequent use of teat dip- ping, it can be assumed that by correcting these deficien- cies, udder health and milk quality could also be improved. Conclusion Relatively high mastitis prevalence was revealed in this study. S. aureus, C. bovis, S. agalactiae and coagulase nega- tive staphylococci caused most of the infections. These bacteria are easily spread from cow to cow at milking. Interestingly, peat was found to associate with higher mastitis prevalence. These results suggest that the mastitis situation could be improved by improving milking proce- dures and hygiene. Furthermore, the farms had clearly defined, separate work tasks between personnel. Clearer motivation-based approach for the responsibilities of employees and supervisors would contribute to the pre- vention of mastitis. Competing interests The author(s) declare that they have no competing inter- ests. Authors' contributions LH took part in all aspects of investigation including plan- ning, microbiological laboratory work and drafting of the manuscript. She carried out the sampling. TH-B partici- pated in planning the study and drafting the manuscript. IS participated in planning and performing microbiologi- cal laboratory work. AO coordinated somatic cell count- ing in laboratory. VM carried out the data analyses and participated in drafting the manuscript. Acknowledgements This study was supported by The Foundation of Walter Ehrström, Research and Science Foundation of Farmos and the Finnish Veterinary Association. References 1. Tilga V, Raid H: Stafülokokilisest mastiidist veistel. Bovine sta- phylococcal mastitis. The Estonian veterinary review 1994, 4:18-19, 70. 2. Klaassen M, Peterson K, Kihu J: Udara tervisliku seisundi hin- damine somaatiliste rakkude arvu (SRA) alusel 1 cm3 piimas. Evaluation of the health status of the udder on basis of somatic cell count (SCC) in 1 cm3 of milk. The Estonian veteri- nary review 1995, 5:196-199. 3. Aasmäe B, Kalmus P, Ööpik T, Klaassen E: Mastiidipatogeenide tundlikkus antibiootikumide suhtes. Antimicrobial suscepti- bility of bovine mastitis pathogens. The Estonian veterinary review 2000, 1:9-11. 4. 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