EPIBuilding a Sustainable Future
Lester R. Brown

Chapter 8. Raising Land Productivity: Raising Protein Efficiency

The second way to raise land productivity in a world where literally billions of people want to diversify their diets by consuming less plant starch and more animal protein is to produce animal protein more efficiently. With some 37 percent of the world grain harvest, or nearly 700 million tons, used to produce animal protein, the potential for more efficient grain use is large.19

World meat consumption increased from 47 million tons in 1950 to 240 million tons in 2002, more than doubling consumption per person from 17 kilograms to 40 kilograms. Consumption of milk and eggs has also risen. In every society where incomes have risen, meat consumption has too, perhaps reflecting a taste that evolved over 4 million years of hunting and gathering.20

As both the oceanic fish catch and the production of beef on rangelands have leveled off, the world has shifted to grain-based production of animal protein to expand output. And as the demand for animal protein climbs, the mix of protein products consumed is shifting toward those that convert grain into protein most efficiently, the lower-cost products. Health concerns have also prompted some people to shift consumption from beef and pork to poultry and fish.

The efficiency with which various animals convert grain into protein varies widely. With cattle in feedlots, it takes roughly 7 kilograms of grain to produce a 1-kilogram gain in live weight. For pork, the figure is close to 4 kilograms of grain per kilogram of weight gain, for poultry it is just over 2, and for herbivorous species of farmed fish (such as carp, tilapia, and catfish), it is less than 2. As the market shifts production to the more grain-efficient products, it raises the productivity of both land and water.21

Global beef production, most of which comes from rangelands, grew less than 1 percent a year from 1990 to 2002. Growth in the number of cattle feedlots was minimal. Pork production grew by 2.5 percent annually, and poultry by nearly 5 percent. (See Table 8-2.) The rapid growth in poultry production, going from 41 million tons in 1990 to 72 million tons in 2002, enabled poultry to eclipse beef in 1995, moving it into second place behind pork. (See Figure 8-1.) World pork production, half of it in China, overtook beef production in 1979 and has continued to widen the lead since then. World beef production, handicapped by inefficient feedlot conversion, is continuing to expand, but just barely. Indeed, within the next decade or so, fast-growing aquacultural output may overtake beef production.22

The big winner in the animal protein sweepstakes has been aquaculture, largely because fish are highly efficient at converting feed into protein. Aquacultural output expanded from 13 million tons in 1990 to 38 million tons in 2002, growing by more than 10 percent a year. China is the leading producer, accounting for two thirds of the global output in 2000. Its output, rather evenly divided between coastal and inland areas, is dominated by finfish (mostly carp), which are produced inland in freshwater ponds, lakes, reservoirs, and rice paddies, and by shellfish (mostly oysters, clams, and mussels), which are produced in coastal regions.23

Over time, China has evolved a remarkably efficient fish polyculture using four types of carp that feed at different levels of the food chain, in effect emulating natural aquatic ecosystems. Silver carp and bighead carp are filter feeders, eating phytoplankton and zooplankton respectively. The grass carp, as its name implies, feeds largely on vegetation, while the common carp is a bottom feeder, living on detritus on the bottom. China's aquaculture is often integrated with agriculture, enabling farmers to use agricultural wastes, such as pig or duck manure, to fertilize ponds, thus stimulating the growth of plankton. Fish polyculture, which typically boosts pond productivity over that of monocultures by at least half, also dominates fish farming in India.24

As land and water become ever more scarce, China's fish farmers are feeding more grain concentrates in order to raise pond productivity. Using this technique, China's farmers raised the annual pond yield per hectare from 2.4 tons of fish in 1990 to 4.1 tons in 1996.25

In the United States, catfish, which require less than 2 kilograms of feed per kilogram of live weight, is the leading aquacultural product. U.S. annual catfish production of 240,000 tons (or two pounds per person) is concentrated in four states: Mississippi, Louisiana, Alabama, and Arkansas. Mississippi, with easily 60 percent of U.S. output, is the catfish capital of the world.26

Public attention has focused on aquacultural operations that are environmentally disruptive, such as the farming of salmon, a carnivorous species, and shrimp. Yet these operations account for only 1.5 million tons of output. World aquaculture is dominated by shellfish and by herbivorous species
mainly carp in China and India, but also catfish in the United States and tilapia in several countries. This is where the potential for growth lies.27


Table 8-2. Annual Growth in World Animal Protein Production, by Source, 1990-2002
Annual Growth
(million tons)
(million tons)
Aquacultural output1
Oceanic fish catch1
1Oceanic fish catch and aquacultural output figures for 2001.
Source: See endnote 22.


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19. USDA, op. cit. note 1.

20. FAO, FAOSTAT, op. cit. note 2, updated 9 January 2003.

21. Feed-to-poultry conversion ratio derived from data in Robert V. Bishop et al., The World Poultry Market-Government Intervention and Multilateral Policy Reform (Washington, DC: USDA, 1990); conversion ratio of grain to beef based on Allen Baker, Feed Situation and Outlook staff, ERS, USDA, discussion with author, 27 April 1992, on Linda Bailey, Livestock and Poultry Situation staff, ERS, USDA, discussion with author, 27 April 1992, and on data taken from various issues of Feedstuffs; pork data from Leland Southard, Livestock and Poultry Situation and Outlook staff, ERS, USDA, discussion with author, 27 April 1992.

22. Table 8-2 compiled from FAO, 1948-1985 World Crop and Livestock Statistics (Rome: 1987), from FAO, FAOSTAT, op. cit. note 2, updated 9 January 2003, from FAO, Yearbook of Fishery Statistics, op. cit. note 2, and from FAO, The State of World Fisheries and Aquaculture 2002 (Rome: 2002); Figure 8-1 and concentration of pork production in China from FAO, FAOSTAT, op. cit. note 2, livestock data updated 9 January 2003.

23. FAO, Yearbook of Fishery Statistics, op. cit. note 2.

24. China's carp polyculture from Rosamond L. Naylor et al., "Effect of Aquaculture on World Fish Supplies," Nature, 29 June 2000, p. 1022; polyculture in India from W. C. Nandeesha et al., "Breeding of Carp with Oviprim," in Indian Branch, Asian Fisheries Society, India, Special Publication No. 4 (Mangalore, India: 1990), p. 1.

25. Krishen Rana, "Changing Scenarios in Aquaculture Development in China," FAO Aquaculture Newsletter, August 1999, p. 18.

26. Catfish requirements from Naylor et al., op. cit. note 24; U.S. catfish production data from USDA, ERS-NASS, Catfish Production (Washington, DC: February 2003), p. 5.

27. FAO, State of World Fisheries and Aquaculture 2002, op. cit. note 22.


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