Of the grain consumed within the United States, 24% of the wheat, 50% of the soybeans 56% of the barley, 62% of the oats, 76% of the corn, and 93% of the sorghum gets fed to farm animals. Combined with the 61 million acres of hay harvested and fed to livestock, approximately 200 million acres of the United States' 334 million acres of cropland (60%) is used to feed farm animals. Another 650 million acres of land consists of pasture and range used for grazing cattle. About 35% of all the land in the United States is thus used by the animal agriculture industry! A mere 7 million acres is used to grow all the fruits, vegetables, and nuts in the US.[22]

Meat production wastes a lot of energy. A vegan diet requires 1/2 the fossil fuels to produce its food than a nonvegetarian diet. An ovo-lacto-vegetarian diet consumes an intermediate amount of fossil fuels. The number of food calories produced for each fossil fuel calorie expended is 4.2 for soybeans, 2.5 for corn, and 2.2 for wheat, but 0.15 for chicken, 0.07 for beef, and 0.04 for pork.[18] Hence, corn is 60 times more fuel efficient to produce than pork.

Animal agriculture wastes a lot of food. Animals are inefficient at converting plants to meat. Grazing cattle must eat ~20 kg of forage to produce 1 kg of beef.[22] Hay- and grain-fed cattle are more efficient (because they are confined in feed lots expending less energy) but the ratio is still 11 to 1.[1,22] Chickens (broilers) are most efficient with a 3.5 to 1 conversion efficiency.[22] To make 1 kg of milk, a dairy cow must consume 0.8 kg of feed[22] and 4-5 kg of water.[1]

Meat production wastes a lot of land. One hectare of land can produce 7500 kg of corn, 6500 kg of rice, or 1900 kg of soybeans. If instead that land is used for meat production, one gets only 490 kg of pork or a mere 70 kg of beef![18]

America's topsoil is being lost 20 times faster than it gets produced. To offset the lower productivity of cropland, large amounts of fertilizers are poured into the soil.[19]

Cattle grazing is a major source of soil erosion on range lands, causing the expansion of deserts. Seventy-five percent of the world's semi-arid range lands (ie, 25% of all land) have suffered moderate desertification -- a 25% drop in productivity.[13]

Agriculture consumes 80% of the water in the United States. Groundwater is being withdrawn 25% faster than it gets replenished.[17]

Agriculture is the number one cause of water pollution. The Environmental Protection Agency reports that 36% of rivers and streams and 39% of lakes are impaired by pollution. Agriculture is responsible for 70% of the river pollution and 49% of the lake pollution.[23]

In the US 130 times more animal manure is produced than human waste. A single hog farm being built in Utah is expected to produce more waste than the entire city of Los Angeles. Spills from waste storage lagoons on hog farms killed 10 million fish in North Carolina in 1995.[24] One spill released into a river enough waste to fill 2 Exxon Valdez oil tankers, killing nearly all aquatic life for 17 miles downstream! During the preceding 10 years, 250 other farms in North Carolina had been cited for pollution.[8]

In the Gulf of Mexico, nutrients from farm runoff, including animal waste, are linked to the formation of a 7,000 square mile "dead zone" of hypoxia (low oxygen) where most aquatic life cannot survive.[24]

Animal waste is a leading suspect for the growing numbers of toxic microbes in coastal waters. One such microbe, Pfiesteria piscicida, killed 450,000 fish in North Carolina and 30,000 fish in the Chesapeake Bay in 1997. Humans exposed to Pfiesteria have suffered memory loss, respiratory problems and skin rashes.[24] Seventy-five percent of the Pfiesteria outbreaks have occurred in waters over-enriched with nutrient (ie, manure).[23]

The growing world meat production (increase of 5-fold since 1950 and still growing) drives deforestation, due to the need for more land to grow animal feed and to graze livestock.[25] More than one-half of the forest land cleared is for agriculture.[19]

Livestock production is the largest source of human-caused methane emission. Methane is a very potent greenhouse gas contributing to global warming.[25]