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Lecture 2 8/31/11 E1
Water
Question | Answer |
---|---|
Why is Water Important | -vital -cheapest and most abundant nutrient -animals survive longer without feed than water (up to 60 days w/o feed, 7 days w/o water) -only 1% of the world's water is "fresh" |
Total Body Content | -45-85% (avg. 60-70%) -younger>older animals |
Water in the Body | -blood: 90-95% -tissues: 70-90% (intracellular, extracellular, urinary and gastrointestinal) |
Water Functions | -nutrient/waste transport -metabolic/chemical reactions -aids digestion/absorption -regulates body temp -regulates ionic concentrations -body structural component -lubricates/cushions |
Non-Essential Water Sources | -drinking water -water in/on feed (air dry feed has about 10%) -metabolic water (byproduct of many reactions, 5-10% of total water intake) -gastrointestinal secretions (mouth/saliva, true stomach/acid, duodenum/pancreatic & bile "juice") |
Water Loss | -urine -feces -respiration -perspiration -product (milk and eggs) |
Effects of Water Restriction | -reduced feed intake (immediate) -reduced production (especially high producers) -weight loss (dehydration) |
Effects on Water Consumption | -environmental temperature and humidity (heat stress) -dry matter (DM) intake -dietary factors (water content, fiber, salt, protein) -physiological state (lactation, etc.) |
Water Consumption | -unstressed, moderate temperature :water intake = 2-3 x DM intake :hot weather-can be 10 x DMI -average 1200 lb cow :hot summer day :eats 70lb of summer pasture :consumes 27 gallons (225lb) of water (grass and drink) |
Effects on Water Quality | -organoleptic (odor & taste) -physiochemical (pH, total dissolved solids, hardness) -toxic compounds (heavy metals, toxic minerals, hydorcarbons) -excess minerals (nitrates, sodium, sulfates, iron) -bacteria |
Essential Water Sources | -well (tank, waterers) -dugout -stream/pond -snow |