<P> Water pollution due to animal waste is a common problem in both developed and developing nations . The USA, Canada, India, Greece, Switzerland and several other countries are experiencing major environmental degradation due to water pollution via animal waste . Concerns about such problems are particularly acute in the case of CAFOs (concentrated animal feeding operations). In the US, a permit for a CAFO requires implementation of a plan for management of manure nutrients, contaminants, wastewater, etc., as applicable, to meet requirements under the Clean Water Act . There were about 19,000 CAFOs in the US as of 2008 . In fiscal 2014, the EPA (Environmental Protection Agency) concluded 26 enforcement actions for various violations by CAFOs . Environmental performance of the US livestock industry can be compared with several other industries . The EPA has published 5 - year and 1 - year data for 32 industries on their ratios of enforcement orders to inspections, a measure of non-compliance with environmental regulations: principally, those under Clean Water Act and Clean Air Act . For the livestock industry, inspections focused primarily on CAFOs . Of the 31 other industries, 4 (including crop production) had a better 5 - year environmental record than the livestock industry, 2 had a similar record, and 25 had a worse record in this respect . For the most recent year of the five - year compilation, livestock production and dry cleaning had the best environmental records of the 32 industries, each with an enforcement order / inspection ratio of 0.01 . For crop production, the ratio was 0.02 . Of the 32 industries, oil and gas extraction and the livestock industry had the lowest percentages of facilities with violations . </P> <P> With good management, manure has environmental benefits . Manure deposited on pastures by grazing animals themselves is applied efficiently for maintaining soil fertility . Animal manures are also commonly collected from barns and concentrated feeding areas for efficient re-use of many nutrients in crop production, sometimes after composting . For many areas with high livestock density, manure application substantially replaces application of synthetic fertilizers on surrounding cropland . Manure was spread as a fertilizer on about 15.8 million acres of US cropland in 2006 . Manure is also spread on forage - producing land that is grazed, rather than cropped . Altogether, in 2007, manure was applied on about 22.1 million acres in the United States . Substitution of animal manure for synthetic fertilizer has important implications for energy use and greenhouse gas emissions, considering that between about 43 and 88 MJ (i.e. between about 10 and 21 Mcal) of fossil fuel energy are used per kg of N in the production of synthetic nitrogenous fertilizers . </P> <P> Manure can also have environmental benefit as a renewable energy source, in digester systems yielding biogas for heating and / or electricity generation . Manure biogas operations can be found in Asia, Europe, North America, and elsewhere . The US EPA estimates that as of July 2010, 157 manure digester systems for biogas energy were in operation on commercial - scale US livestock facilities . System cost is substantial, relative to US energy values, which may be a deterrent to more widespread use, although additional factors, such as odor control and carbon credits, may improve benefit / cost ratios . </P> <P> Grazing (especially, overgrazing) may detrimentally affect certain wildlife species, e.g. by altering cover and food supplies . However, habitat modification by livestock grazing can also benefit some wildlife species . For example, in North America, various studies have found that grazing sometimes improves habitat for elk, blacktailed prairie dogs, sage grouse, mule deer, and numerous other species . A survey of refuge managers on 123 National Wildlife Refuges in the US tallied 86 species of wildlife considered positively affected and 82 considered negatively affected by refuge cattle grazing or haying . Such mixed effects suggest that wildlife diversity may be enhanced and maintained by grazing livestock in some places while excluding livestock in some places . The kind of grazing system employed (e.g. rest - rotation, deferred grazing, HILF grazing) is often important in achieving grazing benefits for particular wildlife species . </P>

Which is not an associated affect of raising animals for food