livestock: the herds and flocks a person owns, counted as movable wealth
This word comes from the verb "to acquire" (קנה), and that origin shapes its whole sense. It does not name animals in general; it names the animals a person has gotten and now holds as property, the goats, sheep, cattle, donkeys, and camels that make up a herder's working capital. In the world of Genesis, a man's standing was measured in exactly this: Abraham was "very rich" in it, Isaac's grew until the Philistines envied him, and Job's flocks and herds were the first line in the ledger of his greatness.
Because the word already carries the idea of acquired wealth, it slides easily between two shades. Most often it points to the animals themselves, the living herds that graze, breed, and can be struck down in a plague or driven off as plunder. At other times the focus shifts from the beasts to the holding they represent, the herder's substance, what he is worth. The two are never far apart, since for these people the livestock simply was the wealth.
The word is close kin to two relatives from the same root: one names the act or price of buying (מִקְנָה), and one names acquired property in general (קִנְיָן). This word is the concrete middle term, property you can see grazing on the hillside.