Table 2.
Univariate associations between potential risk factors and Campylobacter spp. colonization at high level (>123 000 c.f.u./g in pooled caecal samples; results from 2314 batches included in the UK poultry industry study on enhanced biosecurity and Campylobacter colonization, UK, 2011–2013)
| Variable | Categories | No. (%) of batches >123 000 c.f.u./g | No. of batches ⩽123 000c.f.u./g | P value (χ2)* |
|---|---|---|---|---|
| Harvest occasion | Thinning | 532 (48·3) | 570 | <0·001 |
| Depopulation | 824 (68·0) | 388 | ||
| Biosecurity | Model farms | 943 (53·9) | 806 | <0·001 |
| Control farms 1 | 304 (76·2) | 95 | ||
| Control farms 2 | 20 (66·7) | 10 | ||
| Control farms 3 | 89 (65·4) | 47 | ||
| Welfare in model farms | Standard | 588 (53·5) | 512 | 0·038 |
| Higher | 305 (53·0) | 271 | ||
| Freedom food† | 50 (68·5) | 23 | ||
| Hybrid in model farms | Cobb 500 | 183 (48·4) | 195 | 0·001 |
| Cobb 500 & Ross 308 | 18 (72·0) | 7 | ||
| Ross 308 | 613 (54·5) | 511 | ||
| Ross 708 | 69 (50·4) | 68 | ||
| JA 87 | 57 (70·4) | 24 | ||
| Empty days in model farms | 1–7 days | 233 (51·2) | 218 | <0·001 |
| 8–14 days | 585 (54·4) | 491 | ||
| 15–21 days | 57 (48·3) | 61 | ||
| 22–47 days | 35 (72·9) | 13 | ||
| n.a. | 446 (71·8) | 175 | ||
| Days from thinning to depopulation in model farms | 1–3 days | 143 (48·8) | 150 | <0·001 |
| 4–6 days | 344 (54·4) | 288 | ||
| 7–9 days | 215 (58·0) | 156 | ||
| 10–12 days | 99 (57·2) | 74 | ||
| 13–18 days | 60 (60·6) | 39 | ||
| n.a. | 495 (66·4) | 251 | ||
| Processors dealing with batches of control farms 1 | Q | 54 (77·14) | 16 | 0·088 |
| R | 58 (79·5) | 15 | ||
| S | 99 (81·8) | 22 | ||
| T | 93 (68·9) | 42 | ||
| Practice of partial depopulation in model farms | Thinning had been practised | 555 (66·6) | 279 | <0·001 |
| Thinning had not been practised | 46 (48·4) | 49 |
n.a., Not available.
*
χ2 test on (r × c) tables.
†
In addition to the specific welfare conditions the category requires rearing of hybrid JA 87.