A system for feeding farm animals comprises two milk tanks and a drawing line. The two milk tanks are configured to receive a stored full milk quantity and the drawing line comprises two drawing line portions each comprising a drain valve and each connected to one of the two milk tanks. A preparing unit is configured to prepare a liquid ration and a connecting line configured to connect the drawing line with the preparing unit. a cleaning unit comprises at least one cleaning agent container configured to receive a cleaning agent, and a cleaning agent supply apparatus configured to supply cleaning agent from the cleaning agent container to the two milk tanks. A control is configured to actuate the cleaning unit, the preparing unit, and each drain valve to guide the cleaning agent guided from one of the two milk tanks through the connecting line into the preparing unit.