is rising faster than any other region over the past decade, are similarly instituting factory farming (FAO Food and Agriculture Organisation of U.N., Report, 2008). A major byproduct of livestock farming is animal waste. Thus, animal husbandry leads to point source pollution. One of the major problems associated with animal farming involves the movement of excessive nutrients from manure and other byproducts to soil, water and air causing significant environmental problems. In the U.S., the production of livestock and their feedcrops transports about one-third of the nitrogen and phosphorous discharged (from all sources) into freshwater. Besides the nutrients, the other major polluting agents resulting from livestock farming are pathogens and antibiotics and hormones, fertilisers, and the pesticides used to spray feed crops.
Elements present in animal waste such as nitrogen, phosphorus, potassium, and other minerals are essential nutrients for plant growth. However, the manure may run-off during rainfall and pollute the waterways if inadequately contained. Uncontrolled and prolonged discharge of animal waste into waterways can add excessive amounts of nutrients to the waterways causing excessive growth of algae or algal blooms which may be toxic and consume large amounts of oxygen when decaying, thereby reducing the dissolved oxygen concentration in water, and killing fish and other organisms through the process of eutrophication.
Pathogens including protozoan parasites such as Cryptosporidium parvum and Giardia duodenalis, bacteria such as Salmonella, Campylobacter, Escherichia coli, and Listeria monocytogenes and viruses are commonly present in manure and may runoff to surface waters with the possibility of their eventual transmission to animals and humans (USDA, United States Department of Agriculture, 2008).
Animal wastes including wastewater and manure can have large concentrations of pharmaceutically active compounds such as hormones and antibiotics