I posted this before, but I think it is important enough to post again. The factor in meat production that is often forgotten is water. This is from a book, by Gabriel Cousins, MD,thus no link and since the book has been published in 2000 the numbers might not be up-to-date.

Livestock use approximately 50% of all water consumption in the US. Livestock produce twenty times the excrement as the human population of the US. This increases the nitrate/nitrit water pollution. Extensive water use for livestock is pushing us closer t a clean water shortage. It requires 60-100 times more water to produce beef a pound of beef than a pound of wheat.

Livestock requires excessive water usage because the land needed to grow grain for livestock takes up 80% of the grain produced, and water is needed for the animals. When one considers the water needed for this extra grain and for the care of livestock, a flesh-food diet creates the need for 4500 gallons per day per meat-eater as compared to 300 gallons peer day for a vegan. A vegan saves approximately 1'500'000 gallons per year compared to a flesh- and diary eater.

We simply cannot escape the fact that raising animals for meat and diary has a disastrous effect on our ecological system. Us livestock regularely eat enough grain and soy to feed the US population five times over.

The total world livestock regularly eat about twice the calories as the human world population.

By cycling our plant protein through the beef, the conversion of beef protein is between one-tenth and one-twentieth of the plant protein yield. This is a 100% loss of complex carbohydrates and a 95% loss of calories, and calorie resources when so many people in this world suffer from malnutrition.