We have heard that the spirits of these mountains, assuming whatever shapes they like, walk in the woods upon their own precipices. If they are displeased with those who inhabit the forests, then transforming themselves to lions and beasts of prey, they will kill the offenders. We are thus bound to worship the mountains and sacrifices to cattle. What have we to do with Indra? Cattle and mountains are our gods.

In plain words: Krishna says they have heard that the mountain spirits take any shape and roam the woods. If angry with forest people, they can become lions or wild beasts and kill them. So the cowherds should honor the mountains and their cattle, not Indra, because cattle and mountains are their true gods.