The Environmental Food Crisis

How many people can be fed with the cereals allocated to animal feed?

effective manner, wood glucose can, to a large extent, replace cereals as a feed source for both ruminants and monogastric animals. Other fibrous plant sources such as straw, leaves and nutshells are also available in large quantities. Finding ways to feed the world’s livestock is therefore a primary challenge (Keyzer et al ., 2005). Other sources for feed that are not fully exploited include sea- weed, algae and other under-utilized marine organisms such as krill. However, their potential is uncertain, since technological challenges still remain. In addition, the impact of their harvest- ing on the ecosystem is of concern. The use of waste provides a much greater potential for alternative sources of animal feed. By 2050, 1,573 million tonnes of cereals will be used annually for non-food (FAO, 2006a), of which at least 1.45 million tonnes can be estimated to be used as animal feed. Each tonne of ce- real can be modestly estimated to contain 3 million kcal. This means that the yearly use of cereals for non-food use repre- sents 4,350 billion kcal. If we assume that the daily calorie need is 3,000 kcal, this will translate into about 1 million kcal/year needed per person. From a calorie perspective, the non-food use of cereals is thus enough to cover the calorie need for about 4.35 billion people. It would be more correct to adjust for the energy value of the animal products. If we assume that all non-food use is for food- producing animals, and we assume that 3 kg of cereals are used per kilogram animal product (FAO, 2006b) and each kilogram of animal product contains half the calories as in one kg cereals (roughly 1,500 kcal per kg meat), this means that each kilogram of cereals used for feed will give 500 kcal for human consump- tion. One tonne cereals used for feed will give 0.5 million kcal, and the total calorie production from feed grains will thus be 787 billion kcal. Subtracting this from the 4,350 billion calorie value of feed cereals gives 3,563 billion calories. Thus, taking the energy value of the meat produced into con- sideration, the loss of calories by feeding the cereals to animals instead of using the cereals directly as human food represents the annual calorie need for more than 3.5 billion people.

availability of cereal for human consumption. For other feed sources to become a sustainable alternative to the current use of cereals, their exploitation must not be resource-demanding. This poses a big challenge, since most of the easily available feed sources have already been fully exploited, although some alternatives still exist. Cellulose is the most abundant biological material in the world, but the energy it contains is not readily available for ani- mal production. Due to the interest in using this material for bioethanol production, there are currently large research pro- grams underway to chemically and enzymatically degrade this cellulose into glucose. If this becomes possible and in a cost-

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