title: Use of the regression analysis technique to determine the true phosphorus digestibility and the endogenous phosphorus output associated with corn in growing pigs.
abstract: The objectives of this study were to determine true phosphorus (P) digestibility and the endogenous P output associated with corn for growing pigs using the regression analysis technique. Four barrows, average initial body weight of 25 kg, were fitted with a T-cannula and fed four diets according to a 4 x 4 Latin square design. Four cornstarch-based diets, containing four levels of P at 0.7, 1.5, 2.2 and 2.8 g/kg dry matter intake (DMI), were formulated from corn. Each experimental period comprised 8 d with 4-d adaptation and 4-d collection of ileal digesta and fecal samples. The apparent ileal and fecal P digestibility values in corn were affected (P < 0.05) by P contents in the assay diets. The apparent ileal and fecal P digestibility values increased from -51.0 to 33.3% and from -41.4 to 39.1%, respectively, as P content increased from 0.7 to 2.8 g/kg DMI. Linear relationships (P < 0.05), expressed as g/kg DMI, between the apparent ileal and fecal digestible P and the total intake of dietary P, suggested that true P digestibility and the endogenous P outputs associated with corn can be determined by the regression analysis technique. There were no differences (P > 0.05) in true P digestibility values (54.0 +/- 6.5 vs. 59.8 +/- 8.5%) and the endogenous P outputs (0.693 +/- 0.128 vs. 0.670 +/- 0.160 g/kg DMI) between the ileal and the fecal determinations. The endogenous fecal P output represented 12.3% and 25.8% of the daily total and available P requirements in growing pigs recommended by the National Research Council in 1998. The present literature data of apparent digestibility and availability underestimate the true digestive utilization of P in corn for growing pigs by approximately 35%. Current diet formulation on the bases of total, apparent P digestibility and availability values in corn inevitably leads to P overfeeding and excessive P excretion in pigs.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Yingran
authors.initials: Y
authors.lastname: Shen
authors.forename: Ming Z
authors.initials: MZ
authors.lastname: Fan
authors.forename: Ayodele
authors.initials: A
authors.lastname: Ajakaiye
authors.forename: Tania
authors.initials: T
authors.lastname: Archbold
mesh_terms: D000818:Animals; D001682:Biological Availability; D004063:Digestion; D005243:Feces / Q000737:chemistry; D007082:Ileum / Q000378:metabolism*; D007408:Intestinal Absorption; D008297:Male; D010758:Phosphorus / Q000378:metabolism*; D016226:Phosphorus, Dietary / Q000008:administration & dosage* / Q000378:metabolism / Q000493:pharmacokinetics; D012044:Regression Analysis; D013552:Swine / Q000254:growth & development / Q000378:metabolism*; D003313:Zea mays / Q000737:chemistry
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus