The earth has been attributed as a cow.It has been given the metaphor of a cow. Seeing the earth without yajna, without foodgrains and suffering from drought, the king Pruthu as a shephered wanted to burn it.
Pruthu milked the earth which took the form of a cow and obtained a vast amount of milk as food. Similary, a king should milk the earth as a cow. He should bring her up with farming activities and protect the people from starvation. The earth should be milked for certaion time and in certain quantity.