BACTERIAL CONTENT OF VARIOUS FREE STALL BEDDING
MATERIALS USED IN DAIRY OPERATIONS


LAURA J. RAU
Lake Superior State University
Sault Ste. Marie, MI 49783, USA

	Abstract . Bovine mastitis is an infection of the mammary g1and of dairy cattle.
Mastitis is most commonty caused by bacterial invasion of the udder. Free stall bedding is
considered to be a major source of mastitis pathogens between milkings. The udder of the
cow is in close contact with the bedding and the bacteria it harbors for extended periods of
time. Various beddings, including sand, straw, hay, sawdust, recycled manure, and a
sawdust/hay mixture, were sampled to determine their microbial content. Samples of
bedding were collected from nine different farms on three occasions in the summer of
1992. Analysis of bedding using a serial dilution technique with pour plating was
performed to determined bacterial contamination. Only bacteria known as common
causative agents for mastitis were included in the statistical analysis. These included
Kiebsielia spp., Ascherichia coli (E. coli), Sireptococcus., Siaphylococcus spp., and
Pseudomonas spp. A single tailed analysis of variance was performed for each type of
bacteria to determine ifthe bacterial counts of the beddings differed significantly from
each other. A Tukey-Kramer test was performed on those bacteria for which the null
hypothesis was rejected to determine which beddings differed significantly. The recycled
manure had a significantly high amount of Kiehsiella spp. present. both straw and
sawdust on a cement base were significantly contaminated with A. coli and
Staphylococcus spp. The chopped hay, sawdust on mat base, and sand beddings did not
differ significantly ftom the accepted mean in growth of any type of bacteria. Sand was
found to have the lowest amount of bacterial contamination.



SELECTED RLFERENCES

Eberhart, R.J., et al. 1987. Current Concepts ofovine Mastitis, 3rd ed. National Mastitis
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Hogan, J.S., et al. 1989. Bacterial counts in bedding materials used on nine commercial
dairies. Journal ofDairy Science 72: 250.

Zehner, M.M., et al. 1986. Growth ofenvironmental pathogens in various bedding
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