Submitted to: Encyclopedia of Animal Science
Publication Type: Book / Chapter
Publication Acceptance Date: 7/1/2004
Publication Date: 10/29/2004
Citation: Brown, M.S., Cole, N.A., Greene, L.W. 2004. Water. In: Pond, W.G., Bell, A.W. editors. Encyclopedia of Animal Science. Dekker Encyclopedias. p. 871-873.
Interpretive Summary: Water is essential to the live of all plants and animals. The unique ability of water to facilitate hydration of polar and ionic molecules is critical to the flow of water and metabolites within the body. Water comprises about 50 to 80% of total body weight. About 60% of body water is within the cells and about 40% is outside the cells in the digestive tract, within other organs, and in the spaces between the cells. Saliva provides a major portion of the water within the rumen of cattle and sheep. Livestock are normally provided adequate water; however, during transport from one location to another they may experience periods within out water. Cattle may lose approximately 3% of body weight during loading and unloading for transport plus an additional 0.3 to 0.4% of body weight per hour of transport. Water may comprise 80% of this weight loss. Similar losses are seen in swine transported for 24 or more hours. Drinking water may also contribution significant quantities of minerals to livestock. Factors such as drinking water cation-anion difference may influence animal performance.
Technical Abstract: The polarity and ability of water to facilitate hydration of polar and ionic molecules are central to the flow of water and metabolites within the body. Saliva appears to be an even greater proportion of ruminal fluid than previously thought considering recent observations that some water consumed by drinking in nonsuckling cattle bypasses the rumen, but more intensive study is needed. The ability of sheep to form drier feces than cattle results from tighter junctions between colonic cells and this seems to confer a greater ability to establish an osmotic gradient to retain absorbed water. Cattle may lose approximately 3% of body weight during loading and unloading for transport plus an additional 0.3 to 0.4% of body weight per hour of transport; indirect data suggest that water may comprise 80% of this weight loss. Estimates of the contribution of drinking water minerals to overall cation-anion difference and influence of water cation-anion difference on animal performance are needed.