We feed 20% free choice post rut through shed of velvet. We have a little over 300 acres with a 3k lb feeder in the dead center of the place and a 300 lb feeder in the center of each quadrant of the property. The big one stays full for a long time. The little ones last about 2-2.5 weeks if conditions are bad and they are hitting it hard. If range conditions are good they don't eat much of it, and the little ones may last a couple months.
We started working this property with protein, so we don't have any info on how it was with/without, but in the bad years we have had the past couple seasons we had deer raise twins and never saw a rib except the ones that are so old they have to gum their feed into submission.
It's hell eatin em live