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Table 1 Herd characteristics for study farms and farms participating in the Alberta Johne’s Disease Initiative (AJDI, n (%))

From: Calves shedding Mycobacterium avium subspecies paratuberculosis are common on infected dairy farms

  Study participants ( n= 18) Other AJDI farms ( n= 342)
Herd size   0.691
<50 0 (−) 9 (3)
50 – 99 2 (11) 102 (30)
100 - 149 8 (44) 130 (38)
150 – 199 3 (17) 48 (14)
>199 4 (22) 53 (15)
History of clinical Johne’s disease   0.031
JD has been observed 10 (56) 98 (29)
Don’t know 4 (22) 74 (22)
JD has never been observed 4 (22) 170 (49)
Positive environmental samples   < 0.011
0 positives 2 (11)2 188 (55)
1-3 positives 9 (50) 84 (25)
4-6 positives 7 (39) 70 (20)
  1. 1 P-value based on Chi-square test on contingency table.
  2. 2These 2 herds had no MAP culture-positive environmental samples at the last testing event, but had positive environmental samples in 1 of the 2 previous samplings.