I might think that even all offerings (i.e., individual peace-offerings) were subject to priestly gifts, and that this followed a fortiori, viz.: If chullin (non-consecrated animals), which are not subject to (the giving to the Cohein of) breast and thigh, are subject to priestly gifts (of chullin), then consecrated animals, which are subject to breast and thigh, how much more so should they be subject to priestly gifts!
It is, therefore, written (Vayikra 7:34) "and I have given them (breast and thigh) to Aaron the Cohein." Nothing in addition to what is stated herein. I might think that chullin, too, are subject to (the giving to the Cohein of) breast and thigh, and that it follows a fortiori, viz.: If consecrated animals, which are not subject to priestly gifts (shoulder, cheeks, and maw), are subject to breast and thigh, then chullin, which are subject to priestly gifts, how much more so should they be subject to breast and thigh! It is, therefore, written "And this (shoulder, cheeks, and maw) shall be the judgment of the Cohanim."