Kaushitakagrihyasutra 5.6.3

5.6.3

pravasatastu pretasyāpi vānyavatsāyāḥ payasā tūṣṇīṃnyāyamagnihotram \3\

If [he dies] while on a journey, the deceased [man's] Agnihotra is performed silently with the milk of a cow that has another calf;