What are the ramifications of the Torah's comparison of B'chor Beheimah to Chazeh ve'Shok?
Rashi: It teaches us that it 1 may be eaten (by Kohanim exclusively
This refers to a B'chor Tam, but not to a Ba'al-Mum (See Torah Temimah, note 81).
Rashi writes that the Hekesh teaches that it may be eaten for two days. We should know this from (Devarim 15:20) "Sochalenu
Riva: The Hekesh is needed to disqualify it after more than two days.