If a b'chor attended (or made) a siyum on taanis bechoros but did not partake of any food does he need to fast?
The OP asks about attending the siyum and only eating later at a different place and time?
The Minchas Yitzchak (vol.9:45) and Rav Elyashav (I heard this from Rav Smith) both say (as do others) that the simchah of the siyum is what releases the fast. Therefore, you may eat later and elsewhere. One idea for this is the Gemara (Shabbos 118) that says when there was a siyum on a masechta, they would make a "yom tov". The entire day was infused with the spirit of the siyum.
Of course, since other authorities seem to require the firstborn to also partake of enough food at the siyum itself, it should be done if possible.
As to the opposite, (if the person missed the siyum, but arrived for the food only) there are poskim that say it does not help (Rav Elyashav above and others) however, according to the Minchas Yitzchak above, and others (Minchas Yitzchak (9:45); Harav M. Shternbuch in Teshuvos v'Hanhagos (1:300) quoting Harav Y.Y. Kanievsky who says that it is customary to be lenient in this matter, provided that the person is really "happy" with the siyum taking place.) It is permitted to be lenient.
Of course it is better to attend the siyum.
However, in both cases, it seems the world is lenient.
If a firstborn attending a siyum does not hear the completion of the tractate, or if he does not understand what he hears, or if he is in the shiva period of mourning and is thus forbidden from listening to the Torah material being taught, some authorities rule that subsequent eating would not qualify as a seudat mitzvah and he would therefore be forbidden to break his fast (Ben Ish Chai 1:96:25; Rabbi Shlomo Yosef Elyashiv, Siddur Pesach K'hilchaso, p. 168; Rabbi Ovadia Yosef, Chazon Ovadiah, p. 99). Other authorities allow a firstborn to break his fast under such circumstances (Minchas Yitzchak 9:45; Teshuvos V'hanhagos 1:300, 2:210 in the name of Rabbi Yaakov Yisrael Kanievsky). The Minchas Yitzchak (ibid.) suggests that a firstborn in such a position should at least try to contribute to the siyum in some way, such as by sponsoring or helping to prepare the meal.
In order to break one's fast on a seudat mitzvah, many authorities rule that one must partake of at least a kotevet of food (around 1.5 to 2 oz.) or a melo lugmav of liquid (at least around 1.7 oz.) at the seudah (Minchas Yitzchak, ibid.; Chazon Ovadiah, ibid.; Teshuvos V'hanhagos, ibid.). Other authorities rule that a firstborn need not eat anything at the siyum itself, and that he may break his fast anytime after the siyum (Siddur Pesach K'hilchaso, ibid; Rabbi Yehoshua Menachem Mendel Ehrenberg, Devar Yehoshua 2:81).
This is an interesting question.
Many shuls in my neighborhood have no food at all. Two reasons for that:
- People are hurrying to get to work on time
- The shul kitchen & kiddush room, etc. is usually closed for the week, so there is no place to comfortably make a meal
The main part of the siyum is the "siyum" which means the finishing of the masechta. The meal part is called "se'udah". It is the siyum that exempts the person from fasting, not the se'udah. As a matter of fact, it is the siyum that turns the meal into a se'udat mitzvah, not the other way around.
So, technically, if someone attends the siyum, he is allowed to eat at home or wherever he wants.
Some proof to this concept, can be found in one of the paragraphs said at the end of the siyum. Rav Papa's 10 sons are mentioned because Rav Papa used to make a lavish meal at the end of completing every masechta, and he invited his 10 sons who were also great scholars. Perhaps, it was not that customary to make a meal after the siyum, and he was considered somewhat exceptional for making a bigger deal about this.