Table 5 Multivariable linear regression of F. hepatica eggs per gram (dependent variable) across breed, treatment counts before sampling, flock size, lambing period, sheep grazing land, winter soil and illness or death due to F. hepatica (independent variables)

Co-infection (observed vs not-observed)

2.90

1.44–4.35

< 0.001

Breed

Co-infection vs breed vs treat count before sampling vs flock size vs lambing period vs grazing land type vs winter soil vs illness or death due to liver fluke (P = 0.0001)

Charollais vs mountain breed

7.70

3.48–11.93

< 0.001

Charollais vs Suffolk

4.99

1.43–8.56

0.006

Charollais vs Texal

5.13

1.47–8.79

0.006

Charollais vs Cheviot

6.34

1.67–11.01

0.008

Charollais vs Leicester

6.28

1.36–11.21

0.013

Charollais vs Galway

12.79

1.93–23.64

0.021

Charollais vs other breeds

4.79

0.71–8.87

0.022

Mountain breed vs Suffolk

− 2.72

− 5.52–0.09

0.057*

Mountain breed vs other breeds

− 3.17

− 6.63–0.29

0.073*

Treatment frequency before sampling

4 treatments vs 1

3.38

0.43–6.34

0.025

4 treatments vs 2

3.65

1.18–6.12

0.004

4 treatments vs 3

3.33

0.76–5.89

0.011

Lambing period

March-April (mid-late) vs February-March (mid)

1.97

0.31–3.65

0.021

Sheep grazing land

Lowland and mountain vs lowland

2.54

0.60–4.49

0.011

Illness or death due to liver fluke in last 5 years

No vs several

No vs rarely

− 3.82

− 1.38

− 7.80–0.17

− 2.89– − 0.01

0.060*

0.072*