Tuesday, 8 November 2005 - 8:00 AM
139-1

A Potpourri of Options to Reduce Phosphorus in Broiler Meat Production: Phytase, Electrolytes, Low Phytate Grain; Which Will Get the Job Done?.

John Brake, Peter Plumstead, and Rory Maguire. NC State University, Department of Poultry Science, Campus Box 7608, Raleigh, NC 27695-7608

Broiler meat production in the USA involves both 60 million parent broiler breeders and 9 billion broilers reared each year. Results to date indicate that most of the 4,000 Mg of inorganic phosphate added to breeder laying, but not rearing, feeds can be removed with the addition of phytase if the broiler progeny receive adequate dietary phosphorus for the first 21 days of life. Broilers have a significant environmental impact in terms of phosphorus as each million broilers produces about 16 Mg of fecal phosphorus, of which 80% would normally be produced after 21 days of age. Thus, the opportunity to reduce environmental impact without adversely affecting animal welfare (poor bone quality, higher mortality) or food safety (broken bones, secondary bacterial contamination) should be best accomplished by focusing on the later part of broiler rearing. The use of phytase in broiler feeds has given equivocal results in terms of the reduction in fecal water soluble phosphorus (WSP) because the efficacy of phytase was not precisely known in some cases. Further, even when phytase works correctly and reduces fecal WSP by 35%, the amount of total fecal phosphorus originating from corn and soybean meal remains at 80%. Thus, significant reduction in WSP will require modification of the phytate phosphorus content of common animal feed ingredients and/or innovative approaches to feed formulation such as changing the dietary electrolyte balance (DEB) of broiler diets that historically has been maintained near 250 mEq. Supplemental ammonium chloride was added to reduce the DEB to 160 mEq and increase dietary chloride from 0.32% to 0.56% in a low phosphorus feed. Low phosphorus alone decreased body weight gain but with supplemental ammonium chloride present there was no negative effect on growth while WSP was reduced a further 30%. Thus, new approaches must be explored.

Back to Symposium--Environmental Impact of Strategies to Reduce Dietary Phosphorus
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