Table 4. Results from the multivariate analysis (Mixed effects model).

Variable	Group	OR (95% CI)
Subpopulation	Gilts	-
	New gilts	7.9 (1.4, 43.9)*
	Piglets	4.4 (1.1, 17.1) *
Annual quarter	2nd. Apr, May, Jun	-
	3rd. Jul, Aug, Sep	3.5 (0.2, 54.9)
	4th. Oct, Nov, Dec	16.1 (1.1, 234.7) *
	1st. Jan, Feb, March	43.9 (2.8, 686.8)**

While subpopulation and annual quarter were included as fix effects, sampling visit was included as random effect.

*p<0.05

**p<0.01

***p<0.001