The priests who served in the temple shared in the gifts that were given to God. While the burnt offering was to be burned whole on the altar, portions of other sacrifices were given to the serving priests for their own sustenance (Leviticus 7:35, 2 Chronicles 31:4). Because of the economic hardships that the returned exiles experienced, they were inclined to keep the best of the flock to build up their flocks and herds. Instead, they offered what they felt they could afford. The priests accepted this compromise, fearing that if they insisted on the perfect, they (and God) might receive nothing at all.
8 When you offer blind animals in sacrifice, is that not evil? And when you offer those that are lame or sick, is that not evil? Present that to your governor; will he accept you or show you favor? says the LORD of hosts.