|NEWTON, G.L. - U. OF GA
|HILL, GARY - U. OF GA
Submitted to: American Association of Animal Scientists Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2003
Publication Date: 8/20/2003
Citation: HUBBARD, R.K., NEWTON, G., HILL, G. WATER QUALITY AND THE GRAZING ANIMAL. AMERICAN ASSOCIATION OF ANIMAL SCIENTISTS SYMPOSIUM. ABSTRACT P. 128. 2003.
Technical Abstract: Grazing animals and pasture production impact water quality both through urine and feces dropped by the animals and through fertility practices associated with production of high quality pasture. The two nutrients of primary concern relating to animal production are nitrogen (N) and phosphorus (P). Nitrogen is of concern because high concentrations in drinking water in the nitrate form cause methemoglobinemia (blue baby disease) while other forms of N (primarily nitrite) are considered to be potentially carcinogenic. Phosphorus in the orthophosphate form is of concern because it causes eutrophication of surface water bodies. The impact of grazing animals on soil and water quality is best evaluated at the watershed scale. Such evaluation must include both direct input of animal wastes from the grazing animal and also applications of inorganic fertilizers to produce quality pastures. Watershed scale studies have primarily used the approach of nutrient loadings per land area and nutrient removals as livestock harvests. A number of studies have measured nutrient loads in surface runoff from grazed land and compared loads with other land uses. Concentrations in discharge have been regressed against standard grazing animal units per land area. Watersheds with concentrated livestock populations have been shown to discharge 5 to 10 times more nutrients than watersheds with other land uses. Another major concern with animal production including grazing animals is pathogens which may move from the wastes into surface water bodies. Major surface water quality problems associated with pathogens have been associated with grazing animals, particularly when they are not fenced out from the streams and farm ponds. This paper presents an overview of water quality findings and concerns relating to grazing animals.