Table 3.

Risk factors associated with salmonellosis in free-range pigs. The prevalence of Salmonella on the farm was considered to be a continuous variable or as a categorical variable considering the cut-off of 20% prevalence (low or high prevalence on farms with presence of Salmonella spp. in less than or more than 20% of pigs, respectively). The analysis of the prevalence as a continuous variable or as a categorical was carried out by a multivariable regression or logistic analysis, respectively.

Risk Factors	Statistical Analysis (p Values)
	Univariable		Multivariable
	Prevalence	Low/High	Prevalence	Low/High
(i) Large farms (>100 animals)	0.02	0.06	0.11	0.19
(ii) Feed with A brand	0.13	0.02	0.29	0.008
(iii) Extra feed with grass	0.38	0.02	N.A.	N.A.
(iv) Neither cleaning nor disinfection of silos	0.04	0.02	N.A.	N.A.

N.A.: not applicable because these variables were associated to risk factor “ii”.