Table 1

Crude univariate analyses between seroprevalence of BVL and farm factors in seven prefectures in Japan

Variable and level

Number of herds

Median (IQR1)

P2


Herd size

< 30 head

35

43.3 (13.3, 60.0)

0.514

30--49 head

25

53.33 (16.7, 63.3)

≥ 50 head

30

50.00 (26.7, 73.3)

Cattle introduced into the herd within one year

No

11

46.7 (27.3, 60.0)

0.286

Yes, self-bred cows only

33

52.2 (25.0, 78.0)

Yes, including purchased cows

46

45.0 (13.3, 65.0)

Housing conditions

Tie housing

68

41.9 (13.3, 62.5)

0.001*

Loose housing

22

65.0 (52.2, 78.3)

Availability of own grazing area

Yes

65

43.3 (13.8, 63.3)

0.048*

No

25

52.2 (33.6, 78.0)

Presence of horseflies in summer

Never to seldom

28

26.7 (13.3, 51.8)

0.002*

Sometimes to often

29

47.6 (15.8, 65.0)

Very high

33

63.3 (44.4, 83.0)

Animal dehorning

Yes

58

60.0 (39.2, 73.3)

< 0.001*

No

32

20.0 (8.8, 43.0)

Plastic sleeve used for rectal palpation

One sleeve per cow

73

43.3 (14.5, 68.3)

0.012*

One sleeve for more than one cow

17

60.0 (47.8, 75.0)

Needle used for vaccination

One needle per cow

86

46.7 (16.7, 65.5)

0.100*

One needle for more than one cow

4

64.4 (50.5, 91.7)

Colostrum feeding

No

7

76.7 (60.0, 95.7)

0.003*

From dam to calves

63

42.1 (13.3, 60.0)

Pooled

20

50.0 (36.7, 75.8)


Overall

90

48.1 (17.1, 68.5)


1Interquartile range

2Mann--Whitney U-test for two-level variables or Kruskal--Wallis test for all others

*Incorporated into multivariate model

Results of the Mann--Whitney U-test or the Kruskal--Wallis test showed that cattle housing conditions, availability of own grazing area, presence of horseflies in summer, dehorning, use of a plastic sleeve for rectal palpation, not changing needles between animals during herd vaccination, and colostrum feeding were possibly associated with seroprevalence (p < 0.15). These seven variables were incorporated in the multivariate model.

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

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