How do cows obtain stomach bacteria?

Rumen bacteria has been obtained when they were young calves when they mouthed, licked or eaten various things that contain bacteria that another cow or calf has also mouthed, licked or eaten, thus directly transferring bacteria and thus swallowing it into their digestive tracts. A calf will also get bacteria from suckling on a calf nipple from a bottle or bucket that has not been sterilized, and also from the teat of his dam. Mature cows (and bulls) will ingest bacteria much the same way as a calf will, minus the suckling from a bottle or momma's udder.
Rumen bacteria has been obtained when they were young calves when they mouthed, licked or eaten various things that contain bacteria that another cow or calf has also mouthed, licked or eaten, thus directly transferring bacteria and thus swallowing it into their digestive tracts. A calf will also get bacteria from suckling on a calf nipple from a bottle or bucket that has not been sterilized, and also from the teat of his dam. Mature cows (and bulls) will ingest bacteria much the same way as a calf will, minus the suckling from a bottle or momma's udder.