Table 3.
Hazard ratio (HR; with 95% confidence interval [CI]) estimates for diarrhea or not (0/1) using the Cox regression model accounting for cluster effects at the herd-level in 5,101 calves in 125 Norwegian dairy herds1
| Fixed effect | Class | Herds, N | Calves, n | Estimate (β) | SE | HR (95% CI) | P-value |
|---|---|---|---|---|---|---|---|
| Recorded >50% of all dehornings | Yes | 33 | 1,228 | 2.54 | 0.60 | 12.7 (3.8–42.0) | <0.001 |
| No | 92 | 3,873 | — | — | 1.0 | — | |
| Stall type | Free-stall | 54 | 2,195 | 1.30 | 0.60 | 3.7 (1.1–12.2) | <0.05 |
| Tie-stall | 71 | 2,906 | — | — | 1.0 | — | |
| Purchase of calves during the last year | Yes | 25 | 1,187 | 1.42 | 0.56 | 4.1 (1.4–12.4) | <0.05 |
| No | 95 | 3,712 | — | — | 1.0 | — | |
| No information | 5 | 202 | — | — | — | NS | |
| Slatted concrete floor in group pen | Yes | 69 | 2,739 | 2.17 | 0.68 | 8.9 (2.3–33.1) | <0.05 |
| No | 49 | 2,157 | — | — | 1.0 | — | |
| No information | 7 | 205 | — | — | — | NS | |
| Born during winter | Yes | 1,189 | 0.42 | 0.15 | 1.5 (1.1–2.0) | <0.001 | |
| No | 3,912 | — | — | 1.0 | — | ||
| Born from purchased dam | Yes | 4,362 | −0.68 | 0.37 | 0.5 (0.2–1.1) | 0.07 | |
| No | 739 | — | — | 1.0 | — | ||
| θ (1 - Kendall's τ) | Herds | 125 | 0.60 | 0.07 | — | <0.001 |
1
The cluster effect within herd is assessed by the frailty effect (Kendall's τ).