Food Security: The Challenge of Feeding 9 Billion People

In a wide-ranging review of a broad and complex subject we had limited space to explore fully all the factors affecting resource use in livestock production systems, their relative sustainability and broader impact on the environment ("Food security: The challenge of feeding 9 billion people," H. C. J. Godfray et al., Reviews, 12 February 2010, p. 812). The data in our Table 2 was primarily derived from Food and Agriculture Organization of the United Nations and IPCC reports and were quoted to illustrate some of the issues with livestock production that must be considered in food policy debates. We were aware of the complexities and concluded by stating "[o]f the five strategies we discuss here, assessing the value of decreasing the fraction of meat in our diets is the most difficult and needs to be better understood." We welcome G. Flachowsky's informative analysis, which elaborates some of these complexities and, we think, emphasizes the need for more and better data. There is no clear consensus on how we should compare the impacts of different livestock production systems on processes as diverse as fresh water consumption, provision of human macro and micro nutrients, gaseous emissions, eutrophication of aquatic ecosystems, biodiversity, animal welfare, and human cultural richness. Livestock policy is politically highly charged and the challenge to the research community is to develop disinterested metrics to inform debates on dietary choice, animal health, human physical and economic wellbeing, and environmental sustainability.

H. Charles J. Godfray

Department of Zoology and Institute of Biodiversity at the James Martin 21st Century School, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK.

John R. Beddington

UK Government Office for Science, 1 Victoria Street, London, SW1H OET, UK.

Ian R. Crute

Agriculture and Horticulture Development Board, Stoneleigh Park, Kenilworth, Warwickshire, CV8 2TL, UK.

Lawrence Haddad

Institute of Development Studies, University of Sussex, Falmer, Brighton, BN1 9RE, UK.

David Lawrence

Syngenta AG, CH-4002 Basel, Switzerland.

James F. Muir

Institute of Aquaculture, University of Stirling, Stirling, Stirlingshire, FK9 4LA, UK.

Jules Pretty

Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK.

Sherman Robinson

Institute of Development Studies, University of Sussex, Falmer, Brighton, BN1 9RE, UK.

Sandy M. Thomas

Foresight, UK Government Office for Science, 1 Victoria Street, London SW1H OET, UK.

Camilla Toulmin

International Institute for Environment and Development, 3 Endsleigh Street, London, WC1H 0DD, UK.

I was happy to see the 12 February 2010 special section on Food Security. Unfortunately, as an animal nutritionist, I am disappointed in the livestock portion (pp. 816–817) of H. C. J. Godfray et al.'s Review ("Food security: The challenge of feeding 9 billion people," 12 February 2010, p. 812). Animal scientists involved in breeding, nutrition, keeping, health, and welfare were underrepresented in the group of 10 authors.

Godfray et al.'s Table 2 (p. 817) contains unrealistic values for the drinking water intake, the feed required to produce 1 kg of meat, and methane emissions. It is not clear to me why pigs, sheep, and chickens should consume the same water amounts, independent of keeping form (grazing or intensive), whereas intensively kept cattle should consume about 5 times as much water as grazing animals. Roughly calculated, the water intake of animals amounts to about 3 to 5 times their dry matter (DM) intake, depending on animal performance—diet composition, ambient temperature, and other factors (1–3). A laying hen consumes about 100 g of DM per day and drinks about 300 to 500 g of water per day (not 1.3 to 1.8 liters; this is nearly the body weight of such a hen). No attention was given to animal performances. For example, 1 liter of milk contains nearly 87% water; milk yield, therefore, is an important influencing factor on water intake. Why did the authors not consider the data of various countries' scientific societies, such as the National Research Council in the United States or the Society of Nutrition Physiology in Germany, which deduce and update energy and nutrient requirements for food-producing animals?

Apart from water intake, meat yield is not a clearly defined term. It is not measurable under field conditions. Normally, the hot standard carcass weight, or the empty body weight [meat plus bones (4)] is registered in the slaughtering houses and given as a value to the statisticians. What happens to the other edible fractions such as liver, heart, and, lungs? The values given for cereal to produce 1 kg of meat seem to be unrealistic. Not only cereals, but also food industry by-products are fed to animals. We can produce 1 kg of beef (cattle) without any cereal and only roughage, whereas in the case of broiler chicken meat, more than 1 kg (not only cereals) is required.

The main objective of animal husbandry in North America, Europe, and other regions is the production of edible protein in milk, meat, fish, and eggs. Therefore, the estimation of edible protein of animal origin is better suited as a measure for scientific studies to assess animal production, feed input, and efficiency, as well as outputs of environmental relevance. Our Institute of Animal Nutrition data (5, 6) shows some values on this topic dependent on animal yields measured under European conditions.

Gerhard Flachowsky

Institute of Animal Nutrition, Friedrich-Loeffler-Institute (FLI), Bundesallee 50, D-38116 Braunschweig, Germany.

References

1. J. Kamphues et al., FAL Agricultural Research 57, 255 (2007).

2. U. Meyer, M. Everinghoff, D. Gaedeken, G. Flachowsky, Livest. Prod. Sci. 90, 117 (2004).

3. U. Meyer, W. Stahl, G. Flachowsky, Livest. Sci. 103, 186 (2006).

4. G. M. Peters et al., Environ. Sci. Technol. 44, 1327 (2010).

5. G. Flachowsky, J. Appl. Anim. Res. 22, 1 (2002).

6. G. Flachowsky, S. Hachenberg, J. Consumer Prot. Food Safety 4, 1190 (2009).