title: Measurement of true ileal digestibility of phosphorus in some feed ingredients for broiler chickens.
abstract: An experiment was conducted to estimate the true ileal digestibility of P in wheat, sorghum, soybean meal, and corn distiller's dried grains with solubles (DDGS) in broiler chickens. Four semipurified diets were formulated from each ingredient (wheat and sorghum: 236.5, 473, 709.5, and 946 g/kg; soybean meal and corn DDGS: 135, 270, 405, and 540 g/kg) to contain graded concentrations of nonphytate P. The experiment was conducted as a randomized complete block design with 4 weight blocks of 16 cages each (5 birds per cage). A total of 320 21-d-old broilers (Ross 308) were assigned to the 16 test diets with 4 replicates per diet. Apparent ileal digestibility coefficients of P were determined by the indicator method and the linear regression method was used to determine the true P digestibility coefficients. The results showed that the apparent ileal P digestibility coefficients of wheat-based diets were not influenced (P>0.05) by increasing dietary P concentrations, whereas those of diets based on sorghum, soybean meal, and corn DDGS differed (P<0.05) at different P concentrations. Apparent ileal P digestibility in broilers fed diets with soybean meal and corn DDGS linearly (P<0.001) increased with increasing P concentrations. True ileal P digestibility coefficients of wheat, sorghum, soybean meal, and corn DDGS were determined to be 0.464, 0.331, 0.798, and 0.727, respectively. Ileal endogenous P losses in birds fed diets with wheat, soybean meal, and corn DDGS were estimated to be 0.080, 0.609, and 0.418 g/kg DMI, respectively. In birds fed sorghum-based diets, endogenous P losses were estimated to be negative (-0.087 g/kg DMI). True digestible P contents of wheat, sorghum, soybean meal, and corn DDGS were determined to be 1.49, 0.78, 5.16, and 5.94 g/kg, respectively. The corresponding nonphytate P contents in wheat, sorghum, soybean meal, and corn DDGS were 1.11, 0.55, 2.15, and 4.36 g/kg, respectively. These differences between digestible P and nonphytate P contents may be suggestive, at least in part, of overestimation of P digestibility under the calcium-deficient conditions used in the regression method.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand.
authors.forename: R K
authors.initials: RK
authors.lastname: Mutucumarana
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand V.Ravindran@massey.ac.nz.
authors.forename: V
authors.initials: V
authors.lastname: Ravindran
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, Palmerston North 4442, New Zealand.
authors.forename: G
authors.initials: G
authors.lastname: Ravindran
authors.affiliation: Poultry Research Foundation, University of Sydney, Camden, NSW 2570, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Cowieson
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001835:Body Weight / Q000502:physiology; D002645:Chickens / Q000502:physiology*; D003124:Colorimetry / Q000662:veterinary; D004032:Diet / Q000662:veterinary*; D004063:Digestion / Q000502:physiology*; D002523:Edible Grain / Q000737:chemistry; D007082:Ileum / Q000502:physiology*; D016014:Linear Models; D008297:Male; D016226:Phosphorus, Dietary; D045868:Sorghum / Q000737:chemistry; D013025:Glycine max / Q000737:chemistry; D014908:Triticum / Q000737:chemistry
chemical_list: D016226:Phosphorus, Dietary
keywords: broilers; nonphytate; phosphorus; regression method; true digestibility