an epidemiological study of listeriosis in dairy cattle

7 4 1 2 21 31
8 1 8 2 9 42
9 0 9 6 10 37
10 78 60 41 59 ND
Total 124 111 67 202 211
ND =not done
b) Environmental samples: Samples of soil, grass, water, silage, bedding and milk were
collected monthly from each farm. Samples of soil and grass were collected from
pastures where animals grazed and where silage was made using the sampling scheme
shown in the Figure 6. 1. During pasture sampling maximum care was taken to avoid
cross-contact between grass and soil. The samples were placed in separate bags.
Silage samples were taken from the clamp face using the same sampling
procedure as that for soil and grass. An individual rectal glove was used for each
sample.
During the housing period bedding samples were also collected monthly from
the cubicles and straw yards.
Water samples were collected monthly from troughs located in the houses, yards
and fields. Monthly bulk tank milk samples were also taken. Sterile 60 ml pots were
used to take water and milk samples.
Figure 6. 1. The scheme followed for the collection of environmental samples
3 7 11
• • •
•2 • 4 • 6 • 8 •10
164