(Mishnah): The same applies to an ox or any Behemah (domestic animal) for the following:

Falling into a pit, keeping animals from ascending Mount Sinai (when the Torah was given), Kefel (the double payment of a thief), and returning a lost animal;

Unloading an animal, muzzling an animal, Kil'ayim (working with or crossbreeding diverse species), and (letting it rest on) Shabbos.

And the same applies to Chayos (wild animals) and fowl. If so, why did the Torah say "ox or donkey''? The Torah discusses a usual case.

(Gemara): We learn falling into a pit from "v'Nafal Shamah Shor Oh Chamor'' (this is an inclusion we learn to all animals).

We learn separating from Har Sinai from "Im Behemah Im Ish Lo Yichyeh.''

We learn Kefel from "mi'Shor Ad Chamor'' (an inclusion).

We learn Hashavas Aveidah from "Hashev Teshivem.''

We learn unloading from "Azov Ta'azov.''

We learn muzzling from "Lo Sachsom Shor b'Disho.'' (We learn from a Gezeirah Shavah; elsewhere it says Shor, and the same applies to all animals.)

We learn Kil'ayim from "Behemtecha Lo Sarbi'a Kil'ayim.''

We learn Shabbos from "l'Ma'an Yanu'ach Shorcha v'Chamorcha.''

(Mishnah): And the same applies to Chayos and fowl.

(Shmuel): A sea goose with a domestic goose are Kil'ayim together.

Question (R. Yosi): A Tosefta says unlike this! Rather, an ox and a wild ox, and a donkey and a wild donkey, are Kil'ayim with each other. (If even a sea goose with a domestic goose were Kil'ayim, it should have taught so!)

Answer (Reish Lakish): Rebbi taught a complete Mishnah - "and the same applies to Chayos and fowl'' (even a sea species is Kil'ayim with a land species).

Answer #2 (R. Yochanan): I learned this from [a Beraisa of] Beis Levi. A chicken with a partridge, or a chicken with a peacock, even though they resemble each other, they are Kil'ayim with each other.