When someone takes a vow not to eat meat, what is included in his statement?
Our Gemara quotes a baraita that teaches that aside from fish and grasshoppers (which are kosher), all other meat would be included in the vow. This means poultry as well as parts of the animal that ordinarily are not eaten. Rabbi Shimon ben Gamliel argues that only ordinary meat would be included in the neder. According to this ruling, not only would the flesh of poultry, fish and grasshoppers be permitted, but the innards of the animal (e.g. its liver, heart, etc.) would also be excluded from the prohibition that the person accepted on himself.
Not only in Talmudic times, but even until relatively recently, the internal organs of an animal were not considered edible under ordinary circumstances. At best, the innards of the animal were viewed as being “lower grade” in comparison with the main parts of the animal that were eaten – the muscular part, and, to a lesser extent, the fat of the animal. This applies not only to the windpipe, but even to the liver and spleen, heart, lungs and other inner organs, which were eaten only by poor people who could not afford to purchase regular meat. Traditional “Jewish foods” that are made from these parts of the animal were either made specifically by the poor, or were specially prepared for particular needs (e.g. for someone who was ill).
The baraita continues with an even more difficult statement made by Rabbi Shimon ben Gamliel – “kravayim (innards) are not considered meat and one who eats them is not a person.” This difficult line is simply removed from the Gemara by many commentators. Rashi explains that Rabbi Shimon concedes that for those people who eat these parts of the animals, their vow against eating meat will apply here, too. Nevertheless, someone who pays full price for such meat has removed himself from the normative community.