an epidemiological study of listeriosis in dairy cattle

4 of the farms had their silage analysed (Table 6. 2). Information on the age of
milking cows was available for three farms (Farms A, B and C) (Table 6. 3).
Table 6. 1. The management practices followed by the five farms
Farm A Farm B Farm C Farm D Farm E
type of herd closed closed closed open open
herd size a 110 90 60 130 160
time of calving all year all year all year all year all year
type of housing cubicles
straw yard
cubicles cubicles cubicles cubicles
start of grass silage 21.9.96 all year 5.10.96 10.11.96 b all year
start of maize
silage
4.1.97 14.10.96 NF NF 30.10.96
start of housing 15.10.96 8.11.96 30.10.96 24.11.96 30.10.96
end of grass silage 30.4.97 all year 30.4.97 1.4.97 all year
end of maize silage 31.3.97 continued d NF NF 30.3.97
end of housing 31.3.97 23.4.97 30.4.97 12.4.97 30.3.97
storage of silage clamp clamp clamp clamp clamp
additives in silage N Y Y Y Y
dung c Y Y Y Y Y
history of
listeriosis
Y N Y N N
a the numbers changed over the period of study, b mix of grass silage and whole wheat crops and bought
in grass silage in February, c dung spread on the field where animals grazed or silage was made from, d
still being fed when the study finished, NF not fed, Y yes, N no
Table 6. 2. Results of forage analysis
Farm A* Farm B Farm C Farm E
GS MS MS C1 C2 C1 C2 GS MS
pH 4.3 4.0 3.5 3.5 3.4 4.3 4.4 4.4 4.0
Ash (%) 7.7 3.5 NK 11.1 8.2 7.0 8.1 9 10
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