He says food supplies are not growing enough to meet the demand of seven billion people.
他说，粮食供应的增加，尚不能满足70亿人口的需要。
The world is expected to add two billion more by the middle of the century. And people in emerging economies like China are eating more meat, which requires more animal feed.
预计到本世纪中期全世界会新增人口20亿，诸如中国的新兴经济体会消费更多肉类，这就需要饲养更多动物。
But in twenty-eleven, for the first time, the United States used more maize, or corn, for biofuels than for animal feed.
但2011年，美国在制造生物燃料上用的玉米量首次超过了饲养动物。
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