Table 2. The univariate logistic regression model for risk factors associated with BoHV-1 infection.
| Predictor | Level | No. of Ex. animals | No. of positive BoHV-1 (%) | OR1 (95% CI2) | p-value3 |
|---|---|---|---|---|---|
| Environmental factors | |||||
| Season | Autumn | 139 | 15 (10.79%) | Ref | 0.000 |
| Winter | 72 | 28 (38.9%) | 5.26 (2.57–10.75) | ||
| Spring | 105 | 29 (27.6%) | 3.15 (1.58–6.26) | ||
| Summer | 84 | 18 (21.42%) | 2.25 (1.06–4.76) | ||
| Animal factors | |||||
| Age | Adults | 107 | 8 (7.47%) | Ref | 0.000 |
| Pre-weaned | 100 | 13 (13%) | 1.84 (0.73–4.67) | ||
| Weaned | 95 | 42 (44.2%) | 9.8 (4.2–22.4) | ||
| Yearling | 98 | 27 (27.55%) | 4.7 (2.02–10.96) | ||
| Breed | Holstein | 217 | 40 (18.43%) | Ref | 0.07 |
| Italian Buffalo | 40 | 14 (35%) | 2.38 (1.14–4.96) | ||
| Holstein cross | 61 | 13 (21.3%) | 1.19 (0.59–2.41) | ||
| Native | 82 | 23 (28.04%) | 1.72 (0.95–3.11) | ||
| Sex | Females | 258 | 42 (16.27%) | Ref | 0.000 |
| Males | 142 | 48 (34.04%) | 2.51 (1.55–4.05) | ||
| Management factors | |||||
| Stall type | Tie stalls | 174 | 30 (17.24%) | Ref | 0.028 |
| Free stalls | 226 | 60 (26.54%) | 1.73 (1.06–2.83) | ||
| Housing | Open yards | 186 | 29 (15.59%) | Ref | 0.01 |
| Shaded pens | 132 | 38 (28.78%) | 2.18 (1.26–3.78) | ||
| Closed house | 82 | 23 (28.04%) | 2.11 (1.13–3.93) | ||
| History of respiratory illness | Present | 147 | 72 (48.97%) | Ref | 0.000 |
| Absent | 253 | 18 (7.11%) | 0.09 (0.05–0.16) | ||
1OR: Odds ratio; 2CI, confidence interval (95%); 3p-value ≤ 0.20 was used to detect which variables will be retained in the final multivariate model.