panting of cow, grunting of ox
犨 centers on the heavy, labored breathing sounds of cattle: the panting of a cow or the grunting of an ox. It describes the audible exertion of these animals.
犨 combines 雔 (a pair of birds, likely contributing sound) with 牛 (cow/ox), suggesting the sound of cattle breathing heavily. The exact historical development is uncertain.
Picture a pair of birds (雔) perched on a cow (牛), chirping loudly while the cow pants and grunts beneath them. The combined noise helps you remember the heavy breathing sounds of cattle.
For シュウ, imagine the cow letting out a long, tired "shoo" sound as it pants: "shoo" -> シュウ, like a weary exhale from the ox.
—