Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: September 18, 2002
Publication Date: N/A
Technical Abstract: Phosphorus entering lakes and streams from agricultural activity is a major stimulant to algae growth. The livestock industry, through soil application of manure, is a significant contributor of this phosphorus. One way to reduce phosphorus content of manure is to feed phosphorus to meet the animal's requirement, thus eliminating excess excretion from excess feeding. Excess dietary phosphorus appears in the feces of ruminant animals largely in the form of soluble phosphorus, and is especially vulnerable to runoff. Currently, dairy producers typically feed .45% phosphorus (dry matter basis). Feeding .38% phosphorus would provide sufficient phosphorus for even the highest producing dairy cows. If dairy producers would reduce dietary levels from .45 to .38% this reduction would result in a 20% reduction of excreted phosphorus and approximately a 45% reduction in excreted soluble phosphorus. Beef cows should be supplemented with phosphorus only when fed low quality forages, such as corn stalks, winter pasture, or low quality hay or silage. According to the National Research Council, 0.11 to 0.24% dietary phosphorus is sufficient for lactating beef cows. Feedlot cattle will consume excess phosphorus in the typical feedlot diet, and therefore should not be supplemented with mineral phosphorus sources.