Table 2

Relative risk (odds ratio) for trichostrongyle infections and the quantitative egg output in relation to different variables. Single regression model on ± trichostrongyle faecal egg positive animals. Differences between related figures are statistically significant (p < 0.05).

Categories, examined animals and variables
Relative risk of infection
EPG


Odds ratio
95% Cl
Geometric mean

Lambing time



     Ewes soon after lambing



          Winter
1
-
13
          Spring
8.3
3.4 – 20.1
123
High EPG – values



     Ewes soon after lambing



          Haemonchus negative flocks
1
-
118
          Haemonchus positive flocks
26
10 – 71
776
Different sampling times in the same flocks



     Lambs in Sept. – Oct.
1
-
37
     Lambs in Nov.
5.0
2.8 – 8.7
213
Slaughtering time



     Lambs in Sept. – Oct.



          All lambs slaughtered before Dec. 1
1
-
10
          ≥ 1% of the lambs slaughtered after Dec 1.
3.9
2.5 – 6.1
83
Accommodation from birth to turn out in spring



     Lambs after appr. 4 weeks grazing



          Stable – new grazing area
1
-
3
          Stable – old grazing area
3.8
2.4 – 5.9
22
          Winter area – new grazing area
2.3
1.6 – 3.3
10
          Winter area – old grazing area
9.1
5.6 – 14.6
63
          Permanent outdoors
3.9
2.4 – 6.3
25
Pasture managament



     Ewes not dewormed



     Lambs after appr. 4 weeks grazing



          New grazing area
1
-
4
          Old grazing area
5.9
4.3 – 7.9
53
     Ewes dewormed before turn out



     Lambs after appr. 4 weeks grazing



          New grazing area
1
-
4
          Old grazing area
4.9
2.4 – 10.0
45
Lambs in Sept. – Oct.



          New spring grazing area + New autumn grazing area
1
-
8
          New spring grazing area + Old autumn grazing area
7.4
2.9 – 19.3
156

Lindqvist et al. Acta Veterinaria Scandinavica 2001 42:377   doi:10.1186/1751-0147-42-377