Times have changed. Not so many years ago, farmers were responsible for the entire life cycle of their livestock - from birth through to butchering. Then came the advent of abattoirs, allowing more rapid preparation of meat. Step by step, many industrialized countries have attempted to increase productivity by making livestock rearing more systematic. Gradually, this process has led to the advent of factory farms with huge numbers of animals.

But society is now also seeing the more destructive side of this approach. Living creatures are harder to fit to an assembly-line model, and there have been various problems in recent years. A new extensive study from the Pew Charitable Trusts makes some criticisms of current techniques in the US, while reiterating the need for large-scale livestock farming. The human population is growing rapidly and food production is a primary concern. So total eradication of huge farms is unrealistic. But there is plenty of room for improvement. Overall, the study focuses on public health risks, environmental effects, and animal conditions.

Animal welfare scientists are concerned with enhancing the short lives of livestock and other animals. Small shifts in living conditions can have huge benefits for animals, whether it is providing more comfortable floor cover, providing more feeding stations, or avoiding excessive confinement. Most factory-farmed animals suffer from overcrowding. Forced together with no options, chickens and turkeys become aggressive and may injure or kill each other. To prevent this, they are often debeaked. Physical modifications or confining methods are used in other species.

Other major concerns include the rapid spread of disease in large facilities. Not only does crowding promote transmission, but stressed animals are more susceptible to infection. Recent years have seen outbreaks of bovine spongiform encephalopathy (BSE, or mad cow disease), avian influenza, and other diseases. Many of these diseases have strict reporting programs.

Industrial farms often use antibiotics prophylactically and to promote growth. Resistant strains of bacteria may arise under such conditions. Adverse effects have been found, resulting in European bans. In addition, certain steroids are administered to promote rapid growth, with residues persisting in animal products such as meat, milk, and cheese. Some consumers prefer organic meat to avoid these additional ingredients.

Environmental issues have also been raised. Many animals produce even larger quantities of manure - exceeding its usefulness as fertilizer to become contaminating waste. Pesticides are applied to control both insects and fungal growth, while heavy metals may be deliberately added to animal feed. Nearby waterways then become flooded with nutrients, chemicals, and bacteria, resulting in eutrophication. Airborne emissions around large farms can also affect nearby communities, including pesticides, gases like methane, organic compounds, and even pathogens.

As agriculture has become industrialized, the chain of supply has become more rigid. Farmers (or producers) provide animals under contract to meat packing companies (known as integrators), becoming bound by the terms of the contract and financial obligations.

Ultimately, the commission recommends major changes to industrial farms. Improved animal welfare is important, along with banning unnecessary antibiotic use, integrated monitoring of disease, increased funding for agricultural animal research, more equitable arrangements between producers and integrators, and new waste treatment methods.

On the other hand, some critics of factory farming counter with the argument that eating meat is inherently less resource-efficient. They point at facts such as the following:
• Livestock consume much of the world’s grain production.
• Cattle excrete 40 kilograms of manure for every kilogram of beef produced.
• More land is used for livestock grazing than for growing crops.