During the period that cows may be under medical treatment (for example with antibiotics), they remain within the herd but are recognizable by a colored bracelet that the farmer attaches to their ankle. Milk of ill cows is not collected together with the milk from healthy cows. It is collected separately in a milk-churn. The milk will be collected again together with the milk of the other cows as soon as the cow is perfectly cured and no residues of antibiotics are found in the milk.