Halakhah zu Rut 1:10

The commandment of sanctifying the first-born in the Land of Israel: To sanctify the first-born; meaning to say that all those that are born first, which is to say [that] come out first from the womb of the female - whether with people or with beasts - the males are holy to God; as it is stated (Exodus 13:2), "Sanctify for Me every first-born; the first issue of every womb among the Israelites - man and beast - is Mine." And specifically the beast (behamah) - which is an ox and and a sheep and a goat - but not a wild animal (chayah). And from the impure beasts, only the donkey is [included] in this commandment (Bekhorot 10a). And the content of the commandment with a pure beast is that it is a commandment upon the owners to sanctify it and say, "Behold this is holy." And they are obligated to give the first-born to the priests (Kohanim); and [the latter] offer its fat and its blood on the altar and eat the meat in Jerusalem. And he does not give it immediately when it is born, but rather takes care of it - with [sheep and goats] for thirty days; and with [cattle] for fifty days (Bekhorot 10a). And outside the Land, where we do not have a Temple - according to some commentators (Mordechai in the name of Rabbi Eliezer MiMetz on Avodah Zarah, Chapter 1) - he locks the door in front of it and it dies on its own. But there are [others] of them (Mishneh Torah, Laws of Firstlings 1:10) that said we should always kill it. And if a blemish developed upon it, he can feed it to any man and in any place that the priest wants to give it to him. And it is considered like unsanctified meat (as it is like unsanctified meat) - as it is stated (Deuteronomy 15:22), "the impure and the pure shall eat it, like the gazelle and the deer." And so wrote Ramban, may his memory be blessed, in his Laws of Firstlings (at the end of Chapter 5). And we shall explain the topics of the first-born of a man and the [first-born] of a donkey with the commandment of the redemption of each of them, with the help of God. And they are in this Order and in the Order of Vayikach Korach.