Shabbos, Chapter 5, Mishnah 2. We continue the discussion of which items an animal may go out with on Shabbos and which it may not.
"HaChamor yotzei b'mardaas bizman shehi keshurah lo":
The mardaas is a covering that was placed on a donkey's back to keep it warm. The donkey may go out with it, but only on condition that it is tied onto him; if it is merely resting on him, that is not enough. The reason: when it is not tied, we are concerned that it may fall off, and then the driver will pick it up and carry it himself four cubits in a public domain, a labor forbidden by Torah law.
The Gemara explains that the mardaas must be tied on from before Shabbos, since by doing so the owner demonstrates through his actions that the animal needs this covering, and it is therefore no longer considered a burden upon it. Tying the mardaas on Shabbos itself involves a further problem: the one tying it needs to lean on the animal, and leaning on animals or making use of them is rabbinically forbidden on Shabbos. Therefore, even if he did tie it on Shabbos, it would not be permitted to take the donkey out with the mardaas.
The males and the ewes:
"Zecharim yotz'in levuvin" - the rams, which are the males, go out with a piece of leather tied over their male organ, in order to prevent them from mating with the females.
The ewes - the female sheep go out with their fat tail tied: sometimes they would tie it upward, in a raised position, so that the males would be able to mate with them; and sometimes, the opposite, they tie it downward so that the males will not be able to mate with them, all depending on the season of the year.
"Kevunos" - ewes with abundant wool go out with a covering that protects the wool, so that it will remain soft and white and will not get dirty.
"Ha'izim yotz'os tzerurot":
The goats go out with their udders tied up, in a covering resembling a glove fitted to the udders. Sometimes this is done in order to dry up the udders and stop the production of milk, and sometimes it is tied more loosely, merely so that the milk should not drip onto the ground.
The dispute of the Tannaim:
"Rabbi Yosi oser b'chulan chutz min haRechelin haKevunos" - in Rabbi Yosi's opinion, with all the items listed until now in the Mishnah an animal may not go out on Shabbos. He permits one case alone: ewes going out with the covering that protects their wool, the kevunos.
"Rabbi Yehudah omer: izim yotz'os tzerurot liyabesh, aval lo lechalav" - goats go out with the udder covering when it is tied on tightly in order to dry up the milk, and in that manner it is permitted on Shabbos. But if it was tied on only in order to preserve the milk, it is forbidden, since a loose tie is liable to fall off, and the person will come to pick it up and carry it on Shabbos.
In summary: in this Mishnah we learned that a donkey goes out with a mardaas only when it is tied onto him from before Shabbos, for then it is evident that it is for his needs and is not a burden; the males go out levuvin, the ewes with their tails tied and with the kevunos covering, and the goats with their udders bound. Rabbi Yosi forbids all of these except for the ewes with the wool covering, and Rabbi Yehudah permits goats specifically with a tie meant for drying up the milk, and not with a loose tie meant to preserve the milk.