Explanation #1: Below (54b), Rashi explained that if it is tied from before Shabbos, it is clothing of the donkey. If it is not tied from before Shabbos, it is a load.

Explanation #2: If it is not tied from before Shabbos, it looks like he intends to be Motzi the saddle [to Reshus ha'Rabim].

Explanation #3 (Rav Pores): It looks like he intends to take the animal to a far place.

Implied question: Why didn't he ask that we learn this from the Reisha, which taught "when it is tied"? This implies that if it is not tied, no!

Answer: This is the style of Mishnayos. In Avodah Zarah (35b) it says "these matters [of Nochrim], one may not eat them - pickled foods in which they normally put wine...", and the Seifa (39b) teaches "these matters, one may eat them - pickled foods in which they do not normally put...";

In Chulin (54a), it taught "these are Kosher", and some of them we know from the Reisha!

Question: We should resolve from the Reisha that we discuss when it was tied from before Shabbos, since it needed to teach "when it is tied";

Even without [teaching] this, we know that we discuss when it is tied [now], for if it is not tied, obviously it is forbidden, lest it fall and he come to carry it, like it says here "if you will say..."! Rather, surely the Mishnah means "when it is tied from before Shabbos"!

Answer: We cannot learn from the Reisha. Just the contrary, one might have thought that it taught "when it is tied", to [permit] even if it was tied on Shabbos;

Had it not taught this, one might have thought [to permit] only when it was tied from before Shabbos, but not if it was tied on Shabbos. "When it is tied" teaches that this is not so! Therefore, we infer from the Seifa.

Implied question: We should forbid, because one may move a Kli [on Shabbos] only for something that one may move!

Answer: An animal is considered something that one may move, since he can pull it and lead it anywhere.

Suggestion: Rav Asi bar Noson asked whether it is forbidden [to put a saddle on a donkey on Shabbos] because it looks like he intends to take the animal to a far place.

Rejection: If so, how does [the Gemara] infer that the one who permits [hanging a basket on the neck], all the more so a saddle [is permitted? The reason to forbid a saddle does not apply to a basket!]

Suggestion: He wants to forbid in the Chatzer, due to Reshus ha'Rabim, like it says regarding a woman below (64b)!

Rejection: Regarding an animal they did not decree, like a Beraisa below teaches regarding a bell, and [the animal] may go with it in the Chatzer!

Explanation (Ri): Rather, [Rav Asi asked whether it is forbidden] due to exertion on Shabbos.

Note: Below (DH Tolin), Tosfos Yeshanim gives another explanation.

Implied question: One may scratch an animal [with a wooden Kli that will not make a wound. We do not forbid due to exertion!]

Answer #1: There it has excessive pain (if he will not scratch it).

Answer #2: That is permitted only on Yom Tov, but it is forbidden on Shabbos.

Question: He should untie the Ukaf (a kind of saddle) and shake, and it will fall, like it says below (154b) regarding an animal carrying Tevel! (Sefas Emes did not understand this. The Gemara there permits only to untie!)

Answer: There we discuss sacks. The animal can be harmed (if they are not removed). However, it cannot be harmed due to the Ukaf, therefore they did not permit.

Question: It should be forbidden because he uses a living being, just like it is forbidden to leave a lamp on a date tree on Shabbos, because he uses something attached!

Answer: There, he moves the branches. Here, [hanging a basket] does not move the animal;

Rav Asi bar Noson wanted to wanted to forbid [to put a saddle on a donkey on Shabbos]. Perhaps this is because lest he come to use living beings. (This is an alternate explanation to what Tosfos wrote above in DH Mahu.)

Explanation: This is the name of a king, like it says "Aryoch Melech Elasar." He used this name more than other kings, because it contains "Ari" (lion).

Implied question: The Halachah follows Rav [when he argues with Shmuel] regarding Isurim!

Answer: That is when he argues only with Shmuel. However, here R. Yochanan, whom we follow against Rav, holds like Shmuel, and also the Beraisa of Ukaf is like Shmuel, according to the answer here "this is to warm it, and this is to cool it";

Also the Beraisa "we do not anoint and preen an animal" brought below (53b) argues with Rav, like Rashi explained.

Question: What was the question? Perhaps here we discuss a basket hung from before Shabbos, but to hang on Shabbos is forbidden even in the Chatzer!

Answer: He infers from the fact that it mentioned Reshus ha'Rabim regarding a basket, and not regarding the others. All of them discuss in Reshus ha'Rabim! Rather, it mentioned Reshus ha'Rabim because in the Chatzer it is permitted in every case.

Observation: Even so, they permitted only through calling, but one may not go past the animal and chase it to the city.

Explanation: Rav Yehudah properly knew that Tana'im argue about this, but he prefers to establish the two Stam Beraisos like one Tana.

Explanation #1 (Rashi): "For milk" means that the pouch will receive milk.

Objection: Surely this is a load! According to everyone he is liable, for this is Melachah ha'Tzerichah l'Gufah! (Birkas Avraham - he is liable for Mechamer, i.e. causing an animal to work. If the person needs it, this is Tzerichah l'Gufah. Alternatively, one is liable for Melachos for which if a person did it, it would be Tzerichah l'Gufah.)

Explanation #2 (Rav Pores): "For milk" means to guard the milk in their udders, lest it flow to the ground;

The first Tana permits, for this is like ewes Kevunos. It is considered a garment, even though it is not for [the sheep] themselves, rather, to guard the wool.

Explanation #3 (Ri): "To dry" and "for milk" are both so that their udders will not get scratched, like we say below;

"To dry" is when he does not want the milk. It is permitted, for he puts it tightly [on the udder], so there is no concern lest it fall and he come to carry it;

However, "for milk" he does not want that they will be dry. He does not put it tightly [on the udder]. We can say (perhaps the text should say like in Tosfos ha'Rosh "there is concern") perhaps it will fall and he will come to carry it.

Explanation: The word "Levuvin" means that it will not get close. [Even though we said that it is an expression of closeness, we find that a word connotes the opposite of its meaning,] like "uv'Chol Tevu'asi Sesharesh" (will be uprooted with the root. Normally, Tesharesh is to take root), and many like this.

Implied question: It would have been better to bring Kevulos (the tail is tied down to prevent mating), which truly resembles this (it is to prevent mating, just like Levuvin)!

Answer: [We bring from] Shechuzos (hide is tied under the tail to enable mating) because it was taught first (before Kevulos).