Temurah, Chapter 3, Mishnah 32. The mishnah continues to discuss the temuros of various types of offerings, animal offerings, and the law that governs a temurah. It begins with the todah offering - a thanksgiving offering, which closely resembles shelamim, except that it is accompanied by four kinds of bread, ten loaves of each kind, and the time frame for eating it is shorter.
The offspring of a todah and its temurah:
"V'lad todah u'temurasah" - a todah may come from a female animal as well, so it is possible for it to have offspring; and if a person substituted an unconsecrated animal for it, there is a temurah here.
"U'valdan u'vlad valdan ad sof ha'olam" - whether the offspring of the original animal or the offspring of the temurah, and whether one generation later or countless generations later.
"Harei elu k'todah" - their status is governed by all the laws of the todah, and they are offered in exactly the same manner: like shelamim, with the waving, with the breast and the thigh, with semichah - it is all the same.
"U'vilvad she'einan te'unim lechem" - the todah offering itself requires forty loaves, whereas the temurah and the offspring are exempt from them, as is derived from the verse.
This, then, is the mishnah's first point: the law of the temurah and the offspring of a todah is the same as the law of the todah itself, except for the loaves.
The temurah of an olah and the offspring of the temurah:
The second part of the mishnah turns to the olah offering, which is burned entirely and may also be brought as a voluntary gift. It is important to note that an olah comes only from a male animal, so an ordinary olah cannot have offspring. A temurah, however, can be made with any animal, male or female, cow, goat or sheep, and therefore the temurah of an olah may well be a female. Even though that animal itself is unfit to be offered as an olah because it is female, it can have offspring, and the offspring of the temurah of an olah has the status of the olah itself, so the male offspring of the female temurah may be offered. In the next chapter we will discuss further how to handle the difference between the mother and the offspring.
And so the mishnah says: "Temuras olah u'vlad temurah, te'unim hefshet v'nituach v'chalil la'ishim" - the temurah of the olah offering, and the offspring not of the olah itself (which is male, after all) but of the female temurah. Their law is the same as that of the olah in every respect:
"Hefshet" - they require the flaying of the hide, like an olah.
"V'nituach" - a specific instruction as to how the meat is cut and into which portions.
"V'chalil la'ishim" - all of it is burned on the fire.
The mishnah does not mention the requirement of the accompanying libations or the requirement of semichah, but both apply. The point, then, is that the temurah, and the offspring of the temurah for all generations, are governed by the law of the olah.
Why did Rabbi Eliezer not issue a decree here?
Notice that Rabbi Eliezer makes no exception here: he does not establish a rabbinic law and a penalty for someone who keeps them for the next occasion, and he does not forbid bringing them in later generations. The reason is that todah offerings are not at all common the way shelamim are - a person does not raise animals for the sake of a todah; rather, he brings one when he is saved from a dangerous situation, and that is not a frequent occurrence. So too with the olah: olos come from males, and there is no reason to assume that a person will have female offspring; the temurah itself is likewise uncommon, and therefore there is no decree concerning it, and certainly no decree concerning the offspring of the temurah of an olah.