I don't know if even USDA would give you an absolute answer to your question. Yes, IMHO, 100% organic would mean from birth an animal would not have been exposed to any pesticides or herbicides (directly or residue), animal protein, vaccines and medications. If diseases are indiginous to your area, you may not have to vaccinate. If you have stool tests done and they don't show a worm (internal parasite) load, you may not need to deworm (or you can perhaps use a substitute such as DE or Shaklee Basic-H).
I rather doubt one can get 100%, however, it can be approached.
One of my favorate sayings is 80% of the results come from the first 20% of the effort. That may apply here also. You might not have difficultly going up to perhaps 95% just by grazing on unsprayed pastures and using whole grains as a supplement (including if they are chopped). I would avoid cotton-seed and soybean meal just on the off chance they may have herbicide or pesticide residue. Buy isn't corn also sprayed. Yes, not only in late stages of development, such as cotton and soybean plants may be. In cotton, I'm told some spray something to help the bolts open up for more efficient harvesting. If soybeans have been taken over by grasses, some spray to kill down the grasses before harvesting. Don't buy in any hay unless you known where it come from and how it was grown. The producer may have sprayed for weed control in it.
I differentiate between 'organic' and 'grown under organic conditions'.
Ken S. in WC TN