Midrasch zu Bereschit 8:17

Bring forth (hayetze) with you every living thing that is with you…that they may swarm in the earth (Gen. 8:18). R. Yudan said: havtze is written, but it is read hayetze: that they may swarm in the earth - but not in the Ark. And be fruitful and multiply upon the earth - but not in the Ark. 'Every beast, every creeping thing, and every fowl, whatsoever moves (kol romes) upon the earth (Gen 8:19). R. Aivu said: Kol romes is written fully [with a vav] - it excludes kilayim [mixing species]. After their families: this excludes emasculation. The children of Noah were enjoined concerning seven tings: Idolatry, incest, murder, cursing the Divine Name [blasphemy], civil law, and a limb torn from a living animal. Rabbi Chanina ben Gamliel says: also concerning blood from a living animal. Rabbi Eleazar says: also against mixing species. Rabbi Shime'on ben Yochai says: also against witchcraft. Rabbi Yochanan ben Beroka says: also against emasculation. Rabbi Assi said: The children of Noah were ordered regarding everything stated in the sentence: 'There shall not be found among you any one that makes his son or his daughter to pass through the fire, etc.' (Deut. 18:10) and afterwards 'because it is an abomination for Ad-nai all that do this.' (Deut. 18:12)