According to various studies (e.g. check out http://www.independent.co.uk/life-style/health-and-wellbeing/health-news/the-big-question-is-changing-our-diet-the-key-to-resolving-the-global-food-crisis-809566.html , 100 million tons of grain are being diverted to make biofuel this year, but over seven times as much (760 million tons) will be used to feed animals to produce meat. Depending on the type of animal, it takes up to, and sometimes more than, 10 plant calories to deliver 1 meat calorie. Meat consumption is therefore by far the biggest waste of grain globally.

Possible ways of future nutrition without livestock are presented at http://www.futurefood.org