From: Flock-level risk factors for outbreaks of infectious arthritis in lambs, Norway 2018
Variable | Categories | Total | Case flocks (n = 84) | Control flocks (n = 1414) | ||||
---|---|---|---|---|---|---|---|---|
n | % | n | % | n | % | P-value | ||
Number of lambs (ear-tagged, categorized)a | < 200 | 1014 | 67.7 | 36 | 42.9 | 978 | 69.2 | < 0.0001 |
200–500 | 427 | 28.5 | 36 | 42.9 | 391 | 27.7 | ||
> 500 | 57 | 3.8 | 12 | 14.3 | 45 | 3.2 | ||
Outbreak of infectious arthritis before 2018c | No | 1286 | 85.9 | 18 | 21.4 | 1268 | 89.7 | < 0.0001 |
Yes | 212 | 14.2 | 66 | 78.6 | 146 | 10.3 | ||
Lambing percentageb | ≤ 200 | 592 | 39.7 | 19 | 22.6 | 573 | 39.7 | 0.001 |
> 200 | 898 | 60.3 | 65 | 77.4 | 833 | 60.3 | ||
Breedb | Breed other than Norwegian White Sheep | 301 | 20.5 | 7 | 8.9 | 294 | 21.1 | 0.009 |
Norwegian White Sheep | 1171 | 79.6 | 72 | 91.1 | 1099 | 78.9 | ||
Start of lambing seasonb | April | 1181 | 79.2 | 62 | 73.8 | 1119 | 73.8 | 0.038 |
May | 189 | 12.7 | 9 | 10.7 | 180 | 12.7 | ||
March | 121 | 8.1 | 13 | 15.5 | 108 | 7.7 | ||
Length of lambing seasonb | < 4 weeks | 921 | 61.5 | 44 | 52.4 | 877 | 62.1 | 0.076 |
> 4 weeks | 576 | 38.5 | 40 | 47.6 | 536 | 37.9 |