title: Modifying broiler diets with phytase and vitamin D metabolite (25-OH D(3)): impact on phosphorus in litter, amended soils, and runoff.
abstract: Adding phytase and 25- hydroxycholecalciferol (25-OH D(3)) to broiler diets has been shown effective at reducing total P concentrations in broiler litter. This study was conducted to determine the impact of field application of broiler litter from modified diets on P solubility in litter-amended soils and P losses in runoff. Five broiler diets and their resulting litters were evaluated: a high P diet, a low P diet, each of those basal diets with phytase added, and a low P diet with phytase and 25-OH D(3) added. A field study was initiated at two sites with each of the five broiler litters and a commercial P fertilizer (triple superphosphate [TSP]) applied at the same total P rate (150 kg P ha(-1)) and a control where no P was applied. Soil P was monitored over time at two depths (0-5 cm and 0-15 cm) soils were collected in the spring and fall to perform rainfall simulation studies. Broiler litter or TSP application increased soil water-soluble P and Mehlich 3-P concentrations relative to the control, however there were no consistent differences detected between litter treatments. Results from the rainfall simulation experiments indicate that diet modification with phytase or 25-OH D(3) does not increase the potential for P losses in runoff from amended soils relative to traditional diets. Moreover, broiler diet modification to reduce excreted P could be a potentially effective method for reducing watershed scale P surpluses in areas of intensive broiler production, without raising concerns over soluble P losses from litter-amended soils.
authors.affiliation: Dep. of Environmental Science and Technology, Univ. of Maryland, College Park, MD 20742, USA. mcgrathj@umd.edu
authors.forename: Joshua M
authors.initials: JM
authors.lastname: McGrath
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Sims
authors.forename: Rory O
authors.initials: RO
authors.lastname: Maguire
authors.forename: William W
authors.initials: WW
authors.lastname: Saylor
authors.forename: Roselina
authors.initials: R
authors.lastname: Angel
mesh_terms: D010832:6-Phytase / Q000494:pharmacology*; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002112:Calcifediol / Q000494:pharmacology*; D002645:Chickens; D004032:Diet / Q000662:veterinary*; D004784:Environmental Monitoring; D005430:Floors and Floorcoverings; D006762:Hospitals, Animal; D010758:Phosphorus / Q000737:chemistry* / Q000378:metabolism; D012987:Soil / Q000032:analysis*; D014867:Water / Q000737:chemistry*; D014872:Water Movements
chemical_list: D012987:Soil; D014867:Water; D010758:Phosphorus; D010832:6-Phytase; D002112:Calcifediol