You're not alone.... The odd cow might do it but it's coming off her back to do it. The other half of that equation is that the 100# is about 2.3% fat and 2.1% protein. My observation over the years of pasturing like that was that you could make a lot of volume but you couldn't make much of a cheque without some source of fibre going into them.... We did a lot of pasturing on Italian rye grass... and they'd milk good and sh!t through the eye of a needle... but the components were not in the milk. The same herd on good silage would make 4% + milk.