Table 9.
Results for the GEE predicting positive fPCR status (> 1 × 103 genomes / mL) for cows that tested positive (≥ 50 EU in any one of 4 ELISA tests conducted in parallel) for antibody to MAP in a study on a NZ pastoral dairy farm over 4 seasons (2013–2017)
| Input variable | Coefficient | OR | 95% CI | p-valuea |
|---|---|---|---|---|
| Parityb | ||||
| Primparous | Ref | Ref | ||
| Multiparous | −0.73 | 0.48 | 0.24–0.95 | 0.026 |
| Study year | ||||
| 2013–2014 | Ref | Ref | ||
| 2014–2015 | −0.97 | 0.38 | 0.07–2.17 | 0.278 |
| 2015–2016 | − 0.12 | 0.89 | 0.23–3.47 | 0.869 |
| Interactiond | ||||
| Multiparous 2014–2015 | 1.54 | 4.65 | 0.76–28.46 | 0.097 |
| Multiparous 2015–2016 | 0.46 | 1.59 | 0.33–7.82 | 0.569 |
| ICCe | 0.110 | −0.16 - 0.31 | ||
| Variance within | 0.113 | |||
| Variance among | 0.014 | |||
aSignificance of coefficient
bParity of cow defined as primiparous (≤ 2 years) and multiparous (> 2 years)
cMilking season. Each season uses the preceding season as the referent
dInteraction term between parity and milking season. Overall significance of the interaction term: < 0.0247
eIntra class correlation coefficient