To feed the nine-plus billion people projected to inhabit the earth by 2050, some are proposing that land would be best used through systems producing food consumed directly by humans. There are only two approaches by which this could be accomplished. The first is to harvest forages currently produced and feed them directly to humans. The second is to cultivate grazing land to produce other crops that could be consumed directly by humans. Both of these approaches are impractical on a large scale and have great ecological risks.
Council for Agricultural Science and Technology
Capper, Jude; Berger, Larry; Brashears, Mindy; and Jensen, Helen, "Animal Feed vs. Human Food: Challenges and Opportunities in Sustaining Animal Agriculture Toward 2050" (2013). Economics Technical Reports and White Papers. 16.