The mitzvah of Giving the foreleg cheeks and abomasum to a kohen is one of the 248 positive mitzvot, but who’s responsibility is it? is it the Rav-hamachshir? the consumer? the meat-retailer?
Halacha mandates (Yoreh Deah, 61:28) that the shochet is the personality obligated give the gifts to the kohen – this is true even if the animal is not his. Yet, the owner of the animal is given the choice of which kohen to give it to (Based on the Gemara, Chullin 131a, Bet Din instructs the shochet to give the gifts to a kohen talmid-chacham).
As one of the 24 aveirot that excommunication is levied, Halacha authorizes bet-din to excommunicate the shochet who refuses to give these gifts (Rambam, Hilchot bikkurim u’matnos kehuna). In any event, it is recommended that the shochet refuse to slaughter the animal until he verifies that the owner agrees to give the gifts (Responsa of Rabbi Avrohom ibn Tzayat, published in אבקת רוכל of the בית יוסף).
When are the gifts to be given?
Shulchan Aruch states that the shochet is to separate these parts from the animal immediately after the slaughter (even before the animal is checked for kashrut, this is so since the giving of these parts is a מצוה דאורייתא while the checking is only מדרבנן).
Why the shochet?
So, what it is about the shochet that this mitzvah is placed on his shoulders where we essentially tell him to place his job on the line??
The reasoning here is straightforward; since Shochet is mandated to be generally well versed in torah laws – a talmid chochom- and particularly knowledgeable in the laws of Shechitah (“Dinnei Shechita”), Bet-Din deems him accountable to withhold his shechita so long as the owner refuses to give the foreleg cheeks and abomasum to the kohen. The shulchan gavoah commentary explains the logic;
The obligation of giving the gifts lay upon the Shochet to separate the parts due to the Kohanim. Apparently, the reasoning is that since the average Shochet is a Talmid Chacham, since he completed the prerequisite of understanding the (complex) laws of Shechita and Bedikah. It is assumed that he -as well- is knowledgeable in the details of the laws of giving the foreleg cheeks and abomasum, and will not put the Mitzvah aside. This, however, is not the case with the animal’s owner, since the average owner is an Am ha-aretz not wholly knowledgeable in the laws of the gifts -and procrastinates in completing the Mitzvah (shulchan gavoah to yoreh deah).
The shochet is the one held accountable to do this mitzvah and get it done.