........."The Atri Smriti also mentions homosexuality as a sin and prescribes an expiation measure for the same:
By discharging semen into inhuman females except a cow, into a woman in [her] menses, into others that have no female organs (i.e., a man or a eunuch), or into water one should perform the penance of Santapanam.
(Atri Smriti, Chapter 1, Verse 268)"...........
[Taken from Rickross' answer]
Why a man should not be discharging semen in inhuman females "except for cow"? Can a man discharge semen in a cow.?