Bedding
Whether with loose or tied housing systems, bedding plays an important role in the incidence of mastitis. This is easy to understand when considering the mastitis-infected milk that ends upon the ground, the humidity that favours the development of microbes on bedding, and that cows often spend 14 hours out of 24 in contact with their bedding. In an experiment where cows were housed with and without bedding, the level of mastitis infections doubled where there was no bedding. Inadequate bedding in loose-housed herds, particularly large herds, may lead to serious situations of contagious mastitis.
Different materials used as bedding may affect the growth of different microorganisms. Straw is generally most recommended. There is less rapid development of pathogenic microorganisms with chopped straw and cedar sawdust than with newsprint4. Chopped straw, however, is more favourable to Klebsiella than sawdust16. Sawdust and shavings, particularly if heated, encourage the rapid development of coliforms in general and are often responsible for "epidemics" of coliform mastitis36.