Table 2. Fixed effects risk factors in the final models of soil properties at broiler grow-out farm location associated with probabilities of detecting Salmonella in the samples and drags swabs of litter (n = 76)a.
Outcome/risk factor | Response | Mean (range) or count of sampled houses | Increment modelled | OR (95% CI) for increment or to reference category | p-value |
Litter samples outcome | |||||
Total available water capacity | cm | 25.85 (19.88–32.05) | 1 cm | 0.56 (0.43, 0.75) | 0.0002 |
Moist bulk density | g/cm3 | 1.48 (1.34–1.58) | 0.10 g/cm3 | 3.83 (1.03, 14.22) | 0.0454 |
Latest month annual flooding can start in a normal year | Jan | 60 | 9.42 (1.03, 86.33) | 0.0473 | |
Nov/Dec | 16 | Reference | |||
Drag swabs of litter outcome | |||||
Tolerance to erosion T-factor | Tonne | 4.00 (3.00–5.00) | 1.00 tonne | 0.05 (0.01, 0.28) | 0.0012 |
Rock fragments greater than 7.6–25.4 cm in diameter | % by weight of soil | 0.37 (0.00–1.95) | 0.25% | 1.06 (1.01, 1.11) | 0.0256 |
Natural drainage rate classb | Ordered class | 3 (1–5) | 1 class | 0.13 (0.04, 0.42) | 0.0012 |
Random effects of the broiler farms, complexes, companies, or farm latitude were not found to make significant (p≤0.050) contributions to the variability in the responses in these models.
Soil natural drainage rate classes: Somewhat Excessive (15.2–50.8 cm per hour)–5, Well (5.1–15.2 cm per hour)–4, Moderately Well (1.5–5.1 cm per hour)–3, Somewhat Poor (0.5–1.5 cm per hour)–2, and Poor (0.2–0.5 cm per hour)–1.