(As a foreword, thank you to R' D. Zupnik for answering my previous query regarding Erchin 18a. The following question is similar and relates to Temurah 19b.)
The gemara at the end of Temurah 19b concludes that although R'Shimon does not hold that physical sanctity devolves upon an animal just because financial sanctity has devolved upon it (unless the animal which was financially consecrated was immediately fit to be sacrificed - e.g. heekdeesh zachar lidamav), he does agree that when an animal less than 8 days old has been consecrated, it acquires physical sanctity. The basis for this latter admission is a derivation from Bechor to the laws of Ma'aser Beheimah. This derivation is identified by Bechoros 21b as a gezeira shava.
Although the gezeira shava links only the laws of bechor and ma'aser beheimah, a number of commentaries (cited by Artscroll footnote 27) hold that the same applies to all kodashim. Seemingly, all other kodashim are derived by means of a binyan av from ma'aser beheimah. My question is as follows: Zevachim 50b leaves as a Teiku the question of whether one can make an acrobatic derasha from a gezeira shava to a binyan av. But isn't
that what these commentaries are doing?
Thank you very kindly.
Shalom Spira, Montreal, Canada
Tosfos in Zevachim (114) writes that there is a Gezeirah Shavah "Tachas-Tachas" from Ma'aser. Tosfos seems to say that the Limud to other Kodshim is directly from Bechor.