Not many people think of wildlife displacement, rainforest destruction, pollution or world hunger when asked about the disadvantages of meat production and consumption. True, there are other factors to be considered, but there is no doubt that veganism on a large scale can make a large difference to these problems which can only worsen if little action is taken.
The meat and dairy industries produce a large amount of waste, mostly in the form of slurry and gases. Livestock production and slaughter are contributing factors in polluting water, killing fish and worsening the water quality in rivers. Ammonia, methane and nitrous oxide produced by animals and their waste make up a significant amount of the world's total output. Ammonia can help to form acid rain whilst the latter two gases play a role in the greenhouse effect whereby the atmospheric temperature is expected to rise gradually, with disastrous ecological consequences ahead.
Tropical rainforests form one of the world's most precious ecosystems, home to a variety of animals and plant species. In recent years, they have come to represent the cause of the environmental movement, with their destruction mirroring that of the planet as a whole. Huge areas are being deliberately destroyed by humans. About one-third of the area cleared is to pave way for cattle grazing land, not to mention hard wood like mahogany. Once land has been cleared, it is then subjected to overgrazing and loss in nutrient-rich topsoil over the years. The clearing of forests also contributes to the greenhouse effect by releasing carbon dioxide during burning over vast areas. Indeed, the forests help to keep the planet alive by absorbing carbon dioxide and releasing oxygen. The clearing of forests is accompanied by the displacement of wildlife as their natural habitats are destroyed.
Producing meat costs much more than growing crops. For example, livestock, especially cattle, require large amounts of water compared to the growing of crops and much of the world's grains are actually fed to animals. Demand for water and foodstuff will not decrease. More money is spent in the form of subsidies for the meat and dairy industries and also medical bills resulting from health problems related to eating too much meat.
The world's population is increasing rapidly. Although population control measures seem to be the inevitable solution, at present, there are already millions malnourished or starving and living under the poverty line. Grains can feed about ten times more people if fed directly to them, instead of being used as feed for livestock which is then slaughtered for food. This is because grains cannot be converted into animal protein very efficiently. Per acre of land, it is estimated that cereals yield five times more protein than meat. Up to 15 times as much can be obtained by growing leafy vegetables.