Table 3.
GLMM analysis for animal level risk factors of BTB based on standard interpretations; herd ID nested in study site was considered as random effect (p value for the difference between likelihood ratios was less than 0.001 by chi-square test); n total = 2715 with 39 missing values, n matured female = 1607.
| Risk factor | Class | % positive | Univariate | Multivariable final model | ||
|---|---|---|---|---|---|---|
| Crude OR (95% CI) | P value | Adjusted OR (95% CI) | P value | |||
| Sex* | Male | 2.9 (9/315) | – | – | – | – |
| Female | 5.6 (134/2415) | 2.4 (1, 6.4) | 0.05 | – | – | |
| Age groupδ | Calves | 3.0 (20/674) | – | – | – | – |
| Juvenile | 4.4 (27/617) | 2 (0.9, 4.6) | 0.085 | 2 (1,4.8) | 0.096 | |
| Young adults | 6.4 (32/497) | 4.1 (1.9, 9) | < 0.001 | 3.7 (1.7, 8.8) | 0.002 | |
| Adults | 7.7 (30/391) | 4.9 (2.3, 11) | < 0.001 | 3.7 (1.6, 9) | 0.002 | |
| Matured adults | 7.3 (30/409) | 3.8 (1.7, 8.8) | 0.001 | 3 (1.3, 7.2) | 0.010 | |
| Old adults | 3.1 (4/127) | 1.5 (0.3, 6) | 0.56 | 1.3 (0.2, 5) | 0.760 | |
| Animal origin | Same herd | 4.9 (116/2375) | – | – | – | – |
| Other herd | 7.6 (26/340) | 2.6 (1.3, 5) | 0.005 | 2.4 (1.2, 4.8) | 0.017 | |
| BCS | Poor | 4.6 (12/261) | – | – | – | – |
| Moderate | 6.2 (122/1975) | 0.8 (0.4, 1.8) | 0.624 | – | – | |
| Good | 1.9 (9/479) | 0.5 (0.2, 1.4) | 0.199 | – | – | |
| PregnancyŜ | No | 6.9 (71/1033) | – | – | – | – |
| Yes | 4.4 (25/574) | 0.9 (0.5, 1.6) | 0.70 | – | – | |
| LactationŜ | No | 5 (28/556) | – | – | – | – |
| Yes | 6.5 (68/1051) | 1.6 (0.9,3) | 0.147 | – | – | |
Ŝ
analysis was made using data specific to matured females.
*
sex as a variable did not show significance in the global model, thus not presented in the table.
δ
age category: calves: ≤1 year of age, juvenile: > 1 and < 3 years, young adults: ≥ 3 and < 5 years, adults: ≥ 5 and < 7 years, matured adults: ≥ 7 and < 10 years, old adults: ≥ 10 years.