The child was thoroughly washed with cow urine and then smeared with the dust raised by the movements of the cows. Then different names of the Lord were applied with cow dung on twelve different parts of His body, beginning with the forehead, as done in applying tilaka. In this way, the child was given protection.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
गोमूत्रेण स्नापयित्वा पुनर्गोरजसार्भकम् । रक्षां चक्रुश्च शकृता द्वादशाङ्गेषु नामभिः
gomūtreṇa snāpayitvā punargorajasārbhakam | rakṣāṃ cakruśca śakṛtā dvādaśāṅgeṣu nāmabhiḥ
SB 10.6.20