Table 1 Antibody status in a selection of Swedish organically and conventionally managed dairy herds determined from milk samples from four primiparous cows at three sampling occasions

BRSV

Negative herds (n)

14

18

14

13

14

11

42

42

Prevalence (%) of positive herds (95% CI)^a

81.3 (70.7, 89.5)

73.4 (61.9, 83.7)

79.4 (67.9, 88.3)

79.7 (67.8, 88.7)

78.5 (66.5, 87.7)

82.3 (70.5, 90.8)

Herds going from negative to positive between sampling occasions (n)

-

-

3

7

3

4

6

11

Incidence risk (%) of herd becoming antibody positive (95% CI)^a

-

-

21.4 (4.7, 50.8)

38.9 (17.3, 64.3)

23.1 (5.0, 53.8)

36.4 (10.9, 69.2)

Herds going from positive to negative between sampling occasions (n)

-

-

3

2

4

4

7

6

Prevalence (%) of herds with four of four positive individual samples (95% CI)^a

62.7 (50.8, 73.6)

50.7 (38.4, 63.0)

66.2 (53.7, 77.2)

68.7 (55.9, 79.8)

66.2 (53.4, 77.4)

71.0 (58.1, 81.8)

BCoV

Negative herds (n)

11

16

11

14

14

10

36

40

Prevalence (%) of positive herds (95% CI)^a

85.3 (75.3, 92.4)

76.8 (65.1, 86.1)

83.8 (72.9, 91.6)

78.1 (66.0, 87.5)

78.5 (66.5, 87.7)

83.9 (72.3, 92.0)

Herds going from negative to positive between sampling occasions (n)

-

-

3

4

2

6

5

10

Incidence risk (%) of herd becoming antibody positive (95% CI)^a

-

-

27.3 (6.0, 61.0)

26.7 (7.8, 55.1)

20.0 (2.5, 55.6)

46.2 (19.2, 74.9)

Herds going from positive to

negative between sampling occasions (n)

-

-

3

2

6

3

9

5

Prevalence (%) of herds with four of four positive individual sample (95% CI)^a

78.7 (67.7, 87.3)

68.2 (55.8, 78.8)

69.1 (56.7, 79.8)

64.1 (51.1, 75.7)

67.7 (54.9, 78.8)

66.2 (53.0, 77.7)

Herds negative to both BRSV and BCoV (n)

3

9

5

6

7

4

15

19