The cattle upon a thousand hills
For every beast of the forest is mine - All the beasts that roam at large in the wilderness; all that are untamed and unclaimed by man. The idea is, that even if God "needed" such offerings, he was not dependent on them - for the numberless beasts that roamed at large as his own would yield an ample supply.
And the cattle upon a thousand hills - The idea is, that all - whether wild or tame - belonged to God, and he had a right to them, to dispose of them as he pleased. He was not, therefore, in any way dependent on sacrifices.