title: Adding wheat middlings, microbial phytase, and citric acid to corn-soybean meal diets for growing pigs may replace inorganic phosphorus supplementation.
abstract: Three experiments were conducted with 96 growing Landrace x Yorkshire x Duroc crossbreds to determine the collective effectiveness of cereal phytase from wheat middlings, microbial phytase, and citric acid in improving phytate-P bioavailability in corn-soy diets. In Exp. 1, 40 gilts (7 wk old) were fed five diets for 8 wk. Diets 1, 2, and 3 were low-P, corn-soybean meal diets (CSB) + 0, .1, or .2% inorganic P (Pi) as calcium phosphate, respectively. Diet 4 was a similar corn-soy diet that included 15% wheat middlings (461 cereal phytase U/kg). Diet 5 was the CSB + microbial phytase (1,200 U/kg; Natuphos, BASF, Mount Olive, NJ). In Exp. 2, 16 barrows (8 wk old) were fed two diets for 6 wk. Diet 1 was the same as Diet 3 of Exp. 1 (.2% Pi). Diet 2 was Diet 4 of Exp. 1 + microbial phytase (300 U/kg). In Exp. 3, 40 barrows and gilts (6 wk old) were fed four diets for 6 wk. Diets 1 and 2 were the same as those in Exp. 2. Diet 3 was Diet 2 of Exp. 2 + 1.5% citric acid. Diet 4 was similar to Diet 3 but contained 10 instead of 15% wheat middlings. In Exp. 1, pigs fed the low-P, CSB (Diet 1) had lower (P < .05) ADG, ADFI, plasma Pi concentration, bone strength, and mobility score than pigs of the other four treatments. Measurements for pigs fed the 15% wheat middlings diet were not significantly different from those of pigs fed the CSB + .1% Pi or microbial phytase. In Exp. 2, ADG (P=.06) during wk 1 to 3 and gain:feed ratio (P < .02) and plasma Pi concentration (P < .005) during all weeks favored pigs fed the CSB + .2% Pi compared with the other diet including 15% wheat middlings. In Exp. 3, identical ADG during all weeks and similar plasma Pi concentrations at wk 4 and 6 were observed between pigs fed the two citric acid diets (Diets 3 and 4) and the CSB + .2% Pi (Diet 1). Pigs fed Diet 4 (10% wheat middlings) had even higher (P < .02) gain:feed ratio during wk 1 to 3 than those fed Diet 1. It seems feasible to completely replace calcium phosphate with 10 to 15% wheat middlings, 300 U microbial phytase/ kg, and 1.5% citric acid in the corn-soy diets for growing pigs.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Y M
authors.initials: YM
authors.lastname: Han
authors.forename: K R
authors.initials: KR
authors.lastname: Roneker
authors.forename: W G
authors.initials: WG
authors.lastname: Pond
authors.forename: X G
authors.initials: XG
authors.lastname: Lei
mesh_terms: D010832:6-Phytase / Q000008:administration & dosage*; D000821:Animal Feed; D000818:Animals; D001682:Biological Availability; D015519:Bone Density; D019343:Citric Acid / Q000008:administration & dosage*; D004032:Diet / Q000662:veterinary*; D005260:Female; D008297:Male; D010758:Phosphorus / Q000097:blood; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics; D010833:Phytic Acid / Q000008:administration & dosage / Q000378:metabolism; D013025:Glycine max; D013552:Swine / Q000254:growth & development*; D014908:Triticum; D015430:Weight Gain; D003313:Zea mays
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus; D019343:Citric Acid; D010833:Phytic Acid; D010832:6-Phytase