title: Phosphorus utilization and characterization of ileal digesta and excreta from broiler chickens fed diets varying in cereal grain, phosphorus level, and phytase addition.
abstract: Both intrinsic and exogenous phytase in poultry feeds can alter phytate utilization and the solubility of P excreted. This experiment determined the effects of feeding diets varying in cereal grain, P concentration and phytase addition on phytate and P utilization and P characterization of ileal digesta and excreta. Twelve treatments, consisting of diets based on corn, wheat, barley, or high fat-low lignin oat and 3 P treatments (low P with 0.30% nonphytate P; low P + 1,000 phytase units of phytase; high P with 0.45% nonphytate P), were fed to 300 broilers using a factorial design. Fresh excreta were collected at 20 and 21 d and ileal digesta was collected at 21 d. Ileal digesta and excreta were analyzed for total P, phytate P and Ca, with P composition determined by solution (31)P nuclear magnetic resonance spectroscopy. Excreta samples were also analyzed for water soluble P (WSP). Apparent ileal digestibility coefficients for phytate P and total P ranged from 0.03 to 0.42 and 0.56 to 0.71, respectively. Diets supplemented with phytase had greater phytate P hydrolysis than unsupplemented diets. Apparent total tract digestibility coefficients for phytate P and total P ranged from 0.10 to 0.73 and 0.43 to 0.61, respectively. Across cereal grains, there was almost a 3-fold increase in total tract phytate P hydrolysis with phytase supplementation. The P composition of ileal digesta was predominantly phytate P (70 to 88% of total P), whereas excreta phytate P ranged from 26 to 76% of total P. Excreta WSP ranged from 3.2 to 7.5 g kg(-1) and was least for the barley diets. There was a 25% reduction in excreta WSP from the high P to the low P + phytase diets and a 37% reduction from the high P to the low P diets. As cereal grain had little influence on phytate digestibility, it is unlikely that intrinsic phytase in grain has much influence on phytate utilization by poultry. Both total P and WSP in excreta were reduced by the low P diet and the low P + phytase diet, irrespective of cereal grain, which reduces the risk of P transfer to water bodies when excreta are applied to land as fertilizer.
authors.affiliation: USDA, Agricultural Research Service, Northwest Irrigation and Soils Research Laboratory, 3793 N 3600 E, Kimberly, ID 83341, USA. April.Leytem@ars.usda.gov
authors.forename: A B
authors.initials: AB
authors.lastname: Leytem
authors.forename: G P
authors.initials: GP
authors.lastname: Widyaratne
authors.forename: P A
authors.initials: PA
authors.lastname: Thacker
mesh_terms: D010832:6-Phytase / Q000737:chemistry / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002645:Chickens / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D002523:Edible Grain / Q000737:chemistry / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D008297:Male; D010758:Phosphorus / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010758:Phosphorus; D010832:6-Phytase