Table 2

Final logistic regression model with random herd effect for logit-transformed seroprevalence of BLV in Japan

Variable

Level

β1

SE2

z-value

P of z-value


Intercept

-0.36

0.59

-0.62

0.54

Housing conditions

Tied system

Ref.3

Loose system

0.71

0.316

2.23

0.03

Animal dehorning

No

Ref.

Yes

1.11

0.302

3.66

0.0002

Presence of horseflies in summer

Never or seldom

Ref.

Sometimes or often

-0.24

0.341

-0.70

0.49

Very high

0.82

0.321

2.56

0.01

Colostrum feeding

No

Ref.

From dam to calves

-1.11

0.52

-2.13

0.03

Pooled

-0.90

0.55

-1.65

0.10


1estimated coefficients, 2standard error for the coefficient, 3reference category

Standard deviation in mixing distribution = 1.054, Standard error = 0.099

Starting from the full model with seven variables selected by univariate analyses, the best model was constructed on the basis of AIC. The best model with the smallest AIC included housing system, dehorning, observable presence of horseflies, and direct colostrum feeding. The coefficients (β values) indicate that loose housing, dehorning, and observation of a large number of horseflies in summer were positively associated with seroprevalence on infected farms (β values > 0, p values < 0.05). In contrast, feeding of colostrum was negatively associated with seroprevalence in the infected farms (β = -1.11, p = 0.03)

Kobayashi et al. BMC Veterinary Research 2010 6:1   doi:10.1186/1746-6148-6-1

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