MONTREAL -- From one ecologist's perspective, the American system of farming grain-fed livestock consumes resources far out of proportion to the yield, accelerates soil erosion, affects world food supply and will be changing in the future.
"If all the grain currently fed to livestock in the United States wereconsumed directly by people, the number of people who could be fed would benearly 800 million," David Pimentel, professor of ecology in CornellUniversity's College of Agriculture and Life Sciences, reported at the July24-26 meeting of the Canadian Society of Animal Science in Montreal. Or,if those grains were exported, it would boost the U.S. trade balance by $80billion a year, Pimentel estimated.
With only grass-fed livestock, individual Americans would still get morethan the recommended daily allowance (RDA) of meat and dairy protein,according to Pimentel's report, "Livestock Production: Energy Inputs andthe Environment."
An environmental analyst and longtime critic of waste and inefficiency inagricultural practices, Pimentel depicted grain-fed livestock farming as acostly and nonsustainable way to produce animal protein. He distinguishedgrain-fed meat production from pasture-raised livestock, callingcattle-grazing a more reasonable use of marginal land.
Animal protein production requires more than eight times as muchfossil-fuel energy than production of plant protein while yielding animalprotein that is only 1.4 times more nutritious for humans than thecomparable amount of plant protein, according to the Cornell ecologist'sanalysis.
Tracking food animal production from the feed trough to the dinner table,Pimentel found broiler chickens to be the most efficient use of fossilenergy, and beef, the least. Chicken meat production consumes energy in a4:1 ratio to protein output; beef cattle production requires an energyinput to protein output ratio of 54:1. (Lamb meat production is nearly asinefficient at 50:1, according to the ecologist's analysis of U.S.Department of Agriculture statistics. Other ratios range from 13:1 forturkey meat and 14:1 for milk protein to 17:1 for pork and 26:1 for eggs.)
Animal agriculture is a leading consumer of water resources in the UnitedStates, Pimentel noted. Grain-fed beef production takes 100,000 liters ofwater for every kilogram of food. Raising broiler chickens takes 3,500liters of water to make a kilogram of meat. In comparison, soybeanproduction uses 2,000 liters for kilogram of food produced; rice, 1,912;wheat, 900; and potatoes, 500 liters. "Water shortages already are severein the Western and Southern United States and the situation is quicklybecoming worse because of a rapidly growing U.S. population that requiresmore water for all of its needs, especially agriculture," Pimentel observed.
Livestock are directly or indirectly responsible for much of the soilerosion in the United States, the ecologist determined. On lands wherefeed grain is produced, soil loss averages 13 tons per hectare per year.Pasture lands are eroding at a slower pace, at an average of 6 tons perhectare per year. But erosion may exceed 100 tons on severely overgrazedpastures, and 54 percent of U.S. pasture land is being overgrazed.
"More than half the U.S. grain and nearly 40 percent of world grain isbeing fed to livestock rather than being consumed directly by humans,"Pimentel said. "Although grain production is increasing in total, the percapita supply has been decreasing for more than a decade. Clearly, thereis reason for concern in the future."
EIGHT MEATY FACTS ABOUT ANIMAL FOOD
>From "Livestock Production: Energy Inputs and the Environment"
By David Pimentel
-- WHERE'S THE GRAIN? The 7 billion livestock animals in the United Statesconsume five times as much grain as is consumed directly by the entireAmerican population.
-- HERBIVORES ON THE HOOF. Each year an estimated 41 million tons ofplant protein is fed to U.S. livestock to produce an estimated 7 milliontons of animal protein for human consumption. About 26 million tons of thelivestock feed comes from grains and 15 million tons from forage crops.For every kilogram of high-quality animal protein produced, livestock arefed nearly 6 kg of plant protein.
-- FOSSIL FUEL TO FOOD FUEL. On average, animal protein production in theU.S. requires 28 kilocalories (kcal) for every kcal of protein produced forhuman consumption. Beef and lamb are the most costly, in terms of fossilfuel energy input to protein output at 54:1 and 50:1, respectively. Turkeyand chicken meat production are the most efficient (13:1 and 4:1,respectively). Grain production, on average, requires 3.3 kcal of fossilfuel for every kcal of protein produced. The U.S. now imports about 54percent of its oil; by the year 2015, that import figure is expected torise to 100 percent.
-- THIRSTY PRODUCTION SYSTEMS. U.S. agriculture accounts for 87 percentof all the fresh water consumed each year. Livestock directly use only 1.3percent of that water. But when the water required for forage and grainproduction is included, livestock's water usage rises dramatically. Everykilogram of beef produced takes 100,000 liters of water. Some 900 litersof water go into producing a kilogram of wheat. Potatoes are even less"thirsty," at 500 liters per kilogram.
-- HOME ON THE RANGE. More than 302 million hectares of land are devotedto producing feed for the U.S. livestock population -- about 272 millionhectares in pasture and about 30 million hectares for cultivated feedgrains.
-- DISAPPEARING SOIL. About 90 percent of U.S. cropland is losing soil --to wind and water erosion -- at 13 times above the sustainable rate.Soil loss is most severe in some of the richest farming areas; Iowa losestopsoil at 30 times the rate of soil formation. Iowa has lost one-halfits topsoil in only 150 years of farming -- soil that took thousands ofyears to form.
-- PLENTY OF PROTEIN: Nearly 7 million tons (metric) of animal protein isproduced annually in the U.S. -- enough to supply every American man, womanand child with 75 grams of animal protein a day. With the addition of 34grams of available plant protein, a total of 109 grams of protein isavailable per capita. The RDA (recommended daily allowance) per adult perday is 56 grams of protein for a mixed diet.
-- OUT TO PASTURE. If all the U.S. grain now fed to livestock wereexported and if cattlemen switched to grass-fed production systems, lessbeef would be available and animal protein in the average American dietwould drop from 75 grams to 29 grams per day. That, plus current levelsof plant-protein consumption, would still yield more than the RDA forprotein.
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The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.
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