Srimad-Bhagavatam: Canto 4 - Chapter 1 - Verse 27
Sanskrit:
एवं पृथ्वादय: पृथ्वीमन्नादा: स्वन्नमात्मन: ।दोहवत्सादिभेदेन क्षीरभेदं कुरूद्वह ॥ २७ ॥
ITRANS:
evaṁ pṛthv-ādayaḥ pṛthvīmannādāḥ svannam ātmanaḥdoha-vatsādi-bhedenakṣīra-bhedaṁ kurūdvaha
Translation:
My dear Vidura, chief of the Kurus, in this way King Pṛthu and all the others who subsist on food created different types of calves and milked out their respective eatables. Thus they received their various foodstuffs, which were symbolized as milk.