Rashi, Targum Yonasan: They were fattened at the feeding trough. Radak - this is like "v'Eglon Ish Bari" (Shoftim 3:17) and "Lehavri'achem" (Shmuel I, 20:29).
2)
What are "Re'i"?
1.
Radak: They are from the pasture. Beri'im are fattened in the house.
3)
What are "Barburim Avusim"?
1.
Rashi, Targum Yonasan: They are fattened fowl. Radak - he did not specify which species of bird.
2.
Radak #1: Some say that they are castrated, for they are fatter than others.
3.
Radak citing Koheles Rabah 2:9: They are birds from Barberi'a. They are called Barburim based on their origin.
