| Factor | Level of stress | Number of farms | Number of animals | Number of diseased animals | Number of deceased animals | Number of animal-years at risk |
| Production environment | Low-stress | 386 | 930 | 348 | 31 | 3044.7 |
| High-stress | 408 | 1069 | 501 | 38 | 3430.6 | |
| Total | 794 | 1999 | 849 | 69 | 6475.3 | |
| Farm (environment) | Low-stress |
|
|
|
|
|
| Positive deviants | 15 | 39 | 4 | 2 | 182.2 | |
| Typical farms | 371 | 891 | 344 | 29 | 2862.5 | |
| Total | 386 | 930 | 348 | 31 | 3044.7 | |
| High-stress |
|
|
|
|
| |
| Positive deviants | 12 | 31 | 5 | 3 | 114.3 | |
| Typical farms | 396 | 1038 | 496 | 35 | 3316.3 | |
| Total | 408 | 1069 | 501 | 38 | 3430.6 | |
| Farm | Overall |
|
|
|
|
|
| Positive deviants | 27 | 70 | 9 | 5 | 296.5 | |
| Typical farms | 767 | 1929 | 840 | 64 | 6178.8 | |
| Total | 794 | 1999 | 849 | 69 | 6475.3 |