3.3. Bivariate analysis
The prevalence of AFM1 in bulk tank milk was not modified by season (P ¼ 0.617). The characteristics of the milk farm were not related with the likelihood of AFM1 presence in milk. Neither the number of cow per farm (P ¼ 0.183), the total amount of milk produced per farm (P ¼ 0.213) nor the milk production per cow (P ¼ 0.498) were associated with the presence of AFM1 in milk. However, the milk farms whose cows produced on average more than 21.5 L of milk a day had grater probability to show AFM1 in the milk (P ¼ 0.084) (Tables 1 and 2). The number of cows per milk farm and the total amount of milk produced were highly correlated (r ¼ 0.950).