We have learned (see Massekhet Bekhorot, daf 15), that an animal that was consecrated for sacrifice in the Temple retains much of its sanctity, even if it develops a mum – a blemish – that precludes it from being brought as a korban. Redeeming such an animal permits it to be eaten in an ordinary manner, but deriving other benefits from it, e.g. shearing its wool or renting it for work, would remain forbidden.
The Gemara on today’s daf, quotes a Mishna from Massekhet Bekhorot (daf 31a), which teaches that nevertheless, when a redeemed sacrificial animal is sold for food, it is treated in an ordinary manner: they are sold in the itliz – the meat market – slaughtered in the itliz, and weighed by the litra – a measure of weight – like any other ordinary meat. This stands in contrast with a bekhor – a firstborn – or ma’aser – a tithed animal – that is found to have a mum that precludes it from being sacrificed. Such an animal can only be slaughtered at home and cannot be weighed and sold in the meat market.
Tosafot assume that the prohibition against selling a bekhor or ma’aser that cannot be sacrificed is Biblical, and that it is based on the unique status of animals such as these. The Ramban disagrees, arguing that it is a Rabbinic injunction. Since the profit belongs to private people, it was not permitted to sell the meat and treat it lightly like ordinary meat by selling it in the market in order to gain more profit.
The terms itliz and litra are borrowed from the Greek, with itliz meaning a market square, or a fair and litra representing a measure of weight or volume. Both words have made their way from the Mishna into modern Hebrew usage.