Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.3.15

2.5.3.15

athāhāgnaye sviṣṭakṛte 'nubrūhīti | sa upastṛṇīta ājyamathāsya caroḥ sakṛdavadyatyathopariṣṭāddvirājyasyābhighārayati na pratyanaktyavadānamatikrāmatyatikramyāśrāvyāhāgnim\ sviṣṭakṛtam- yajeti vaṣaṭkṛte juhoti

Thereupon he says, 'Pronounce the invitatory prayer to Agni Svishtakrit!' He then makes an under-layer of butter, takes one cutting from the pap, pours twice butter thereon, without, however, re-anointing the (place of the) cutting; and steps across. Having stepped across, and called for the Sraushat, he says, 'Pronounce the offering-prayer to Agni Svishtakrit!' and pours out the oblation, as soon as the Vashat has been uttered.
16, He then cuts off the Idâ, but no fore-portion. Having invoked (the Idâ), they (the priests) eat it. As many members of (the sacrificer's) household as are entitled to partake of the remains of sacrificial food may eat (of the pap); or the officiating priests may eat it; or, if there be abundant pap, other Brâhmans also may eat of it. The pot having then been covered, before it is quite emptied, they put it away in a safe place, for the 'full-spoon ceremony.' Thereupon they let the calves together with their mothers; and thus the cattle take that nourishment. That night he performs the Agnihotra with rice-gruel. In the morning they milk a cow, which suckles an adopted calf, for the purpose of the offering to the fathers.