I think what ZNT is getting at, and I am making an assumption which we all know what happens when we do this, is the fact that, after a certain time frame, the calf is inefficient at gaining off the cow. This isn't always the case, but that is why creep feeding usually more than pays for itself, as the calf is very efficient at gaining off of grain, only supporting itself, as opposed to a 1400 lb. animal trying to sustain itself as well as feed a live calf and grow another calf inside. This is only the case for a certain time period, but I know there has been research done to say that weaning early is better for the calf and the cow. Having said this, every situation is different, and we usually let the year dictate when we wean. This year we weaned early as we were running out of grass and the calves were eating the creep very well. Some years, if we have adequate rainfall and adequate grass, we will wait to wean until September 1.