1)
Why will Hashem not desire their Korbanos?
1.
Radak: It is like it says in Yeshayah "Lamah Li Rov Zivcheichem" (1:11).
2.
Malbim: Even though they are obligated to offer Olas Re'iyah, Shalmei Chagigah and Menachos, He does not desire them. Even though Olah atone for [Bitul of a] Mitzvas Aseh or transgressing a Lav ha'Nitak l'Aseh (an Aseh fixes transgression of the Lav), He will not accept it, and all the more so Shelamim! So Yirmeyah said "Oloseichem Lo l'Ratzon v'Zivcheichem Lo Arvu Li" (6:20).
2)
What are "Shelem Meri'eichem"?
1.
Rashi: Shelamim of fattened animals. Radak - Shelem is one of them. Meri'eichem is like "v'Chelev Meri'im" (Yeshayah 1:11).
