1) THE DECREE NOT TO SEPARATE "MA'ASER BEHEMAH" TODAY
QUESTION: The Mishnah states that the Mitzvah of Ma'aser Behemah applies both when the Beis ha'Mikdash is standing and when there is no Beis ha'Mikdash. The Gemara asks that if the Mitzvah applies when there is no Beis ha'Mikdash, then why does it not apply nowadays?
The Gemara explains that the Mitzvah of Ma'aser Behemah does not apply today because, as Rav Huna says, the Rabanan enacted a decree that Ma'aser Behemah not be given because of the concern that one of the animals might be a "Yasom," an orphaned animal that was born after the death of its mother, which is not subject to the obligation of Ma'aser Behemah, as the Gemara later (57a) derives from the verse, "Tachas Imo" -- "with its mother" (Vayikra 22:27). The Gemara asks why such a Gezeirah was made only for the time when there is no Beis ha'Mikdash? If there is a concern that an animal is a Yasom, then the Gezeirah should have been made even in the times of the Beis ha'Mikdash!
The Gemara's questions is difficult to understand. We often find that the Rabanan made decrees for specific periods, and the Gemara never asks why the Gezeirah was not made earlier. Every Gezeirah was made according to the Ru'ach ha'Kodesh that the Rabanan received at the particular time that the Gezeirah was needed. For example, the Rabanan instituted that we not blow the Shofar on Rosh Hashanah when Rosh Hashanah occurs on Shabbos. This Gezeirah certainly did not exist in the times of Moshe Rabeinu, but was instituted later in response to the needs of the time. RASHI in Megilah (5a, DH Erev Shabbos) writes that the Gezeirah not to read the Megilah on Purim when Purim occurs on Shabbos was made after the period of the Anshei Keneses ha'Gedolah; the Chachamim instituted that the Megilah not be read on Shabbos lest one carry the Megilah four Amos in Reshus ha'Rabim in search for an expert to teach him how to read it. (The Gezeiros not to blow the Shofar and not to hold the Lulav on Shabbos were made for a similar reason.) The Gemara never asks why this Gezeirah was not made earlier, such as in the times of the Anshei Keneses ha'Gedolah or earlier.
Why does the Gemara ask only here, with regard to the Gezeirah not to separate Ma'aser Behemah lest one of the animals is a Yasom, why the Rabanan did not institute the Gezeirah earlier?
ANSWER: The MINCHAS CHINUCH (#287) explains that the Gemara's question may be understood based on another question that the Acharonim discuss. The Acharonim ask why the Rabanan prohibited blowing the Shofar on Shabbos only due to the concern that one might carry it four Amos in Reshus ha'Rabim. They should have prohibited blowing the Shofar on any day of the week on which Rosh Hashanah falls because of the Isur d'Oraisa against fixing a musical instrument! The Rabanan prohibited playing any musical instrument on Shabbos or Yom Tov, lest the instrument break and one mend it and thereby transgress an Isur d'Oraisa. Why did they not prohibit blowing the Shofar for the same reason?
The MAGEN AVRAHAM (OC 588:4) answers that the Rabanan could not make such a Gezeirah, because such a Gezeirah would prevent the Mitzvah of Shofar from being fulfilled altogether, since the Isur of mending an instrument applies on Yom Tov just as it applies on Shabbos. The Rabanan did not want to abolish the Mitzvah of Shofar entirely. By enacting the Gezeirah only on Shabbos due to the concern that one might carry the Shofar in Reshus ha'Rabim (which is an Isur that applies only to Shabbos and not to Yom Tov), the Rabanan preserved the sanctity of Shabbos while not abolishing the Mitzvah of Shofar entirely (but only in years in which Rosh Hashanah falls on Shabbos). The PRI CHADASH (OC 588:5) adds that the Rabanan could not make a Gezeirah prohibiting the blowing of the Shofar due to the concern that one might mend a broken Shofar, and apply that Gezeirah only to Shabbos but not to Yom Tov, because this would make the Rabanan's decree look senseless, since the Isur against mending an instrument applies to Yom Tov just as it applies to Shabbos. Therefore, the Rabanan made a Gezeirah not to blow the Shofar on Shabbos in order that one not carry the Shofar four Amos in Reshus ha'Rabim, an Isur that applies only on Shabbos.
Similarly, the Rabanan would not have made a Gezeirah not to separate Ma'aser Behemah out of concern that one of the animals might be a Yasom, because such a Gezeirah would abolish the Mitzvah of Ma'aser Behemah entirely. Since the Rabanan did not make such a Gezeirah during the time that the Beis ha'Mikdash stood, why did they make such a Gezeirah after the Churban? Such a Gezeirah looks senseless, because the same concern (that an animal might be a Yasom) exists before the Churban just as it exists after the Churban! Moreover, if the Rabanan were concerned about abolishing the Mitzvah entirely during the time of the Beis ha'Mikdash, then why did they effectively abolish it entirely after the time of the Churban?
This is the meaning of the Gemara's question. If the Rabanan did not want to make a Gezeirah (due to the concern for Yasom) in the times of the Beis ha'Mikdash because doing so would abolish the Mitzvah entirely, then why were they prepared to make such a Gezeirah after the Churban?
The Gemara answers that the Gezeirah indeed was not because of the concern for Yasom, but because of the concern for "Takalah." RASHI (DH Mishum) explains that since there is no Mizbe'ach now, the Ma'aser-animal must be left until it becomes blemished. The Rabanan were concerned that leaving a sanctified animal to graze until it becomes blemished would lead to transgression of the prohibition against shearing, slaughtering, or working with a sanctified animal (before it becomes blemished). This Gezeirah does not apply at all times, and therefore it does not entirely abolish the Mitzvah, because during the times of the Beis ha'Mikdash an animal of Ma'aser Behemah is brought as a Korban right away and is not left to graze.
The Minchas Chinuch points out that it is possible that in the times of the second Beis ha'Mikdash, Ma'aser Behemah was not offered as a Korban (see TOSFOS here, end of DH Ela, and Avodah Zarah 13a, end of DH Ein Makdishin, who in fact says that it is possible that the decree was not made immediately after the Churban of the second Beis ha'Mikdash). However, the question of why the Rabanan did not make a Gezeirah to abolish Ma'aser Behemah during the times of the second Beis ha'Mikdash is not problematic, because the Mishnah in Sukah (41a) says that a number of decrees were made after the Churban of the second Beis ha'Mikdash. There were many decrees enacted at various times in history, and each one was made according to the Ru'ach ha'Kodesh of the Chachamim of that time. The Gemara in Chulin (7a) states that in certain areas of Halachah, a special place was left by the earlier generations of Chachamim so that the later generations could acquire greatness through establishing new laws. Therefore, the Gemara does not ask why the Gezeirah to abolish Ma'aser Behemah was not made during, or immediately after, the period of the second Beis ha'Mikdash. (D. BLOOM)
2) THROWING FORBIDDEN OBJECTS INTO THE SEA
QUESTION: The Gemara quotes a Beraisa that teaches that objects that are Asur b'Hana'ah must be thrown into the "Yam ha'Melach," the Sea of Salt (the Dead Sea). This implies that it is not sufficient to discard such objects in any river or body of water. However, the Gemara elsewhere (Erchin 29a) says that it suffices to throw such items into "a river," implying that they do not need to be thrown specifically into the Yam ha'Melach. How are these Gemaras to be reconciled?
(a) TOSFOS (DH Ma'os) quotes the Gemara in Pesachim (28a) that states that one may discard an object that is Asur b'Hana'ah into any river as long as he first grinds the object into fine pieces, in order to ensure that no one will find the object and use it. When the Gemara in Erchin and elsewhere says that an object that is Asur b'Hana'ah may be thrown into a river, it refers to an object that was ground into fine pieces. If one does not grind the object into fine pieces, then he must throw it into the Yam ha'Melach.
(b) RAV YAKOV KAMINETSKY zt'l (in EMES L'YAKOV, Parshas Mas'ei) points out that the RAMBAM (in Perush ha'Mishnayos to Kelim 15:1, and in Hilchos Tzitzis 2:2) seems to use the term "Yam ha'Melach" to refer to any salt-water ocean. Since rivers feed into the ocean (as the verse says in Koheles 1:7), whatever is thrown into a river will reach the ocean eventually. Accordingly, the two statements in the Gemara do not contradict each other at all.
3) AN ANIMAL SANCTIFIED AS A KORBAN NOWADAYS
QUESTION: The Beraisa teaches that if one sanctifies an animal as a Korban nowadays, when there is no Beis ha'Mikdash, he must lock the animal in a pen and let it starve to death ("Ikur").
The Gemara earlier (35a) discusses old Bechoros which were cared for until they became blemished by themselves. Why were they not starved in the manner that the Beraisa here describes with regard to an animal sanctified as a Korban?
ANSWER: TOSFOS (DH v'Iy) explains that since a Bechor may be eaten once it becomes blemished, by letting it starve to death one causes a loss to the Kohanim. In contrast, no one will suffer a loss if one starves an animal that was sanctified to be a Korban when the Beis ha'Mikdash is not standing. Even if it becomes blemished and redeemed, the money used to redeem it must be destroyed.