Broiler Breeder Diets to Reduce Phosphorus: Manure Composition and Corn Response.
Shaun Casteel, P.O. Box 7619, North Carolina State University-Crop Science Dept., Box 7619, NCSU - Williams Hall, 100 Derieux Street, Raleigh, NC 27695, Daniel Israel, 3131 Williams Hall, Box 7619, USDA-ARS, North Carolina State University, Soil Science Dept. USDA-ARS, Raleigh, NC 27695, Carl Crozier, N. C. State University-Soil Science Dept., 207 Research Station Road, Vernon James Research & Extension Ctr., Plymouth, NC 27962, John T. Brake, Poultry Science, North Carolina State University, Scott Hall 261, Box 7608, Raleigh, NC 27695, and Rory Maguire, Virginia Tech, Dept. of Crop and Soil Env. Sci. (0404), Smyth Hall, Blacksburg, VA 24061.
Poultry diet modification studies have evaluated the effect of altering phosphorus (P) sources, forms, and amendments on poultry performance and P excretion. In one particular study, broiler breeders were fed available P rations at standard and reduced rates of non-phytate P (NPP) with and without the addition of phytase. Manure of the standard and the reduced NPP diets yielded 21.7 and 15.7 g P kg dry manure-1 where calcium (Ca) concentrations were not different. However, standard diet yielded lower Ca:P than the reduced NPP diet, (5.0 and 7.0, respectively). This study examined P availability to corn at rates of 7.5, 15, 30 and 60 mg of total P kg-1 for the low and the high Ca:P broiler breeder manures and triple superphosphate (TSP). Height and leaf area were not different among P sources at the same rates. Greater P rate hasten node development at 30 and 60 mg P kg-1. Shoot:root was lowest for high Ca:P manure at 30 and 60 mg P kg-1 due to the greater root dry matter accumulation. Few differences in leaf and stalk dry matter accumulations were exhibited among P sources. Enhanced root development was linked to greater Ca uptake with high Ca:P manure. Whole plant P uptake was significantly greater for the two manures than TSP at the rate of 60 mg P kg-1. Whereas, water soluble P in the soil was 0.85 mg P kg -1 greater for TSP than for high Ca:P at 60 mg P kg-1. Soil pH increased as P rate increased for both manures, where high Ca:P manure was higher than the untreated control and TSP at 60 mg P kg-1 (6.3 vs. 5.75 and 5.90, respectively). Future research will evaluate P transformation of soils amended with manures of variable Ca:P ratios as related to environmental concerns and bioavailability.