Then there are the costs to do this properly (packaging the correct nutrients in bioavailable forms, for one), which will likely be much greater than simply letting a cow loose in a pasture to do what it does. This is to say nothing of the long-term testing that should be done on any such product — whether it promotes cancer, leads to misfolded proteins, thereby jetting new and interesting prions into the population, etc. The 20th century was marked by morally-unmoored technocrats allowed to run wild; why is the 21st century doubling down on this?