Table 5.

GEE prediction of probability of a positive ELISA test result (≥ 50 EU in any one of 4 ELISA tests conducted in parallel) for primiparous compared to multiparous cows over 4 years of whole herd testing for MAP infection on a NZ pastoral dairy farm over 4 seasons (2013–2017)

Predicted probability (95% CI) of testing ELISA positive
Season	Primiparous	Multiparous	p-value of difference
2013–2014	15.7% (11.1–22.1)	42.8% (37.1–49.4)	< 0.001
2014–2015	3.8% (2.1–6.8)	15.6% (12.8–19.0)	< 0.001
2015–2016	7.8% (5.0–11.9)	8.1% (6.4–10.3)	0.870
2016–2017	2.6% (1.2–5.3)	2.6% (1.7–4.0)	0.946