Table 1.
Descriptive statistics and unadjusted univariable associations from logistic regression models between animal-level BVD serology test status and temporal, animal-, and herd-level independent variables
| Independent variable | BVD antibody -ve (%) | BVD antibody + ve (%) | Total | OR | Lower 95%CI | Upper 95%CI | P-Value |
|---|---|---|---|---|---|---|---|
| TEMPORAL | |||||||
| Year | |||||||
| 2017 | 1071 (91.15) | 104 (8.85) | 1175 | 1.000 | referent | ||
| 2018 | 2286 (94.42) | 135 (5.58) | 2421 | 0.608 | 0.466 | 0.793 | < 0.001 |
| 2020 | 2742 (96.11) | 111 (3.89) | 2853 | 0.417 | 0.316 | 0.550 | < 0.001 |
| ANIMAL LEVEL | |||||||
| Age – months (quartiles) | |||||||
| 10–23 | 1500 (93.05) | 112 (6.95) | 1,612 | 1.000 | referent | ||
| 24–25 | 1284 (95.11) | 66 (4.89) | 1,350 | 0.688 | 0.019 | 0.503 | 0.942 |
| 26–27 | 1365 (93.88) | 89 (6.12) | 1,454 | 0.873 | 0.356 | 0.655 | 1.164 |
| 28–30 | 1950 (95.92) | 89 (4.08) | 2,033 | 0.570 | 0.000 | 0.426 | 0.763 |
| Breed | |||||||
| Aberdeen Angus | 1,116 (94.98) | 59 (5.02) | 1175 | 1.000 | referent | ||
| Charolais | 1,124 (95.09) | 58 (4.91) | 1182 | 0.976 | 0.673 | 1.416 | 0.898 |
| Friesian | 1,170 (93.23) | 85 (6.77) | 1255 | 1.374 | 0.976 | 1.935 | 0.069 |
| Hereford | 892 (94.99) | 47 (5.01) | 939 | 0.997 | 0.673 | 1.477 | 0.987 |
| Limousin | 1,137 (94.51) | 66 (5.49) | 1203 | 1.098 | 0.765 | 1.575 | 0.612 |
| Other | 660 (94.96) | 35 (5.04) | 695 | 1.003 | 0.653 | 1.541 | 0.989 |
| Sex | |||||||
| Male | 3513 (95.44) | 168 (4.56) | 3681 | 0.679 | 0.548 | 0.843 | < 0.001 |
| Female | 2,586 (93.42) | 182 (6.58) | 2768 | 1.000 | referent | ||
| Movement (different last herd to birth herd) | |||||||
| No | 1733 (94.49) | 101 (6.51) | 1,834 | 1.000 | referent | ||
| Yes | 4366 (94.6) | 249 (5.43) | 4,615 | 0.979 | 0.771 | 1.241 | 0.858 |
| Moved during previous year | |||||||
| No | 1677 (94.59) | 96 (5.41) | 1,773 | 1.000 | referent | ||
| Yes | 4422 (94.57) | 254 (5.43) | 4,676 | 1.003 | 0.735 | 1.370 | 0.983 |
| HERD LEVEL | |||||||
| Herd Type (last) | |||||||
| Beef | 337 (92.84) | 26 (7.16) | 363 | 1.160 | 0.761 | 1.770 | 0.489 |
| Dairy | 3,264 (93.77) | 217 (6.23) | 3481 | 1.000 | referent | ||
| Suckler | 2,192 (96.31) | 84 (3.69) | 2276 | 0.576 | 0.446 | 0.746 | < 0.001 |
| Other | 306 (93.01) | 23 (6.99) | 329 | 1.131 | 0.724 | 1.765 | 0.589 |
| Birth Herd size (quartiles) | |||||||
| < 60 (mean: 33.7) | 1515 (95.83) | 66 (4.17) | 1,581 | referent | |||
| 60–119 (mean:88.9) | 1548 (94.39) | 92 (5.61) | 1,640 | 1.364 | 0.987 | 1.886 | 0.06 |
| 120–201 (mean: 157.4) | 1536 (95.17) | 78 (4.83) | 1,614 | 1.166 | 0.834 | 1.630 | 0.37 |
| 202–1574 (mean: 352.7) | 1500 (92.94) | 114 (7.06) | 1,614 | 1.745 | 1.278 | 2.382 | < 0.001 |
| Last Herd size (quartiles) | |||||||
| < 52 (mean: 28.9) | 1537 (96.00) | 64 (4.00) | 1,601 | referent | |||
| 53–109 (mean: 80.6) | 1543 (95.66) | 70 (4.34) | 1,613 | 1.089 | 0.771 | 1.540 | 0.628 |
| 110–225 (mean: 160.3) | 1519 (93.88) | 99 (6.12) | 1,618 | 1.565 | 1.134 | 2.160 | 0.006 |
| 226–3755 (mean: 451.2) | 1500 (92.76) | 117 (7.24) | 1,617 | 1.873 | 1.370 | 2.561 | < 0.001 |
| PI Birth herd year status | |||||||
| Absent | 5890 (95.52) | 276 (4.48) | 6166 | 1.000 | referent | ||
| Present | 209 (73.85) | 74 (26.15) | 283 | 7.556 | 5.339 | 10.694 | < 0.001 |
| PI Last herd year status | |||||||
| Absent | 6003 (94.92) | 321 (5.08) | 6,324 | 1.000 | referent | ||
| Present | 96 (76.8) | 29 (23.2) | 125 | 5.649 | 3.674 | 8.686 | < 0.001 |