title: Efficacy of an Escherichia coli phytase in broilers fed adequate or reduced phosphorus diets and its effect on carcass characteristics.
abstract: Five experiments (EXP) were conducted to assess the efficacy of an Escherichia coli phytase compared with 2 commercially available fungal phytases. In EXP 1 and 2, male broiler chicks were fed experimental diets that included a P-deficient control (0.13% available P; 0.88% Ca) alone or with graded levels of KH(2)PO(4) (0, 0.05, 0.10, or 0.15%) or phytase at levels of 250, 500, 1,000, 2,000, or 4,000 phytase units/kg of E. coli phytase (EXP 1 and 2), fungal phytase 1 (EXP 2), or fungal phytase 2 (EXP 2). In EXP 1 and 2, weight gain and tibia ash (mg/chick and %) responded linearly (P < 0.05) to inorganic P addition. In EXP 2, each level of E. coli phytase released more P than either fungal phytases 1 or 2, whether based on tibia ash weight (mg/chick) or percentage. In EXP 3, 4, and 5, dietary treatments containing adequate or deficient levels of P were fed with or without supplemental E. coli phytase. In EXP 3, weight gain and tibia ash were reduced (P < 0.05) by P deficiency, but gain and tibia ash of chicks fed E. coli phytase (250, 500, or 1,000 phytase units/kg) did not differ (P > 0.05) from that of chicks fed the P-adequate diet. In addition, carcass yield of broilers fed E. coli phytase was not reduced (P > 0.05). In EXP 4, E. coli phytase effectively supported weight gain, tibia ash, breast yield, and leg yield compared with birds fed the P-adequate diet, but clavicle breakage during processing was increased in birds fed E. coli phytase. In EXP 5, E. coli phytase again effectively supported weight gain, and no differences (P > 0.05; compared with the P-adequate diet) were noted for clavicle ash, diameter, or breaking strength. No differences (P > 0.05) in bone breakage during processing were noted among treatments. These results indicate that the addition of E. coli phytase to P-deficient broiler diets improves growth, bone, and carcass performance and is more effective at releasing phytate-bound P than the other phytase products that were tested.
authors.affiliation: Department of Poultry Science, University of Arkansas, Fayetteville 72701, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Pillai
authors.forename: T
authors.initials: T
authors.lastname: O'Connor-Dennie
authors.forename: C M
authors.initials: CM
authors.lastname: Owens
authors.forename: J L
authors.initials: JL
authors.lastname: Emmert
mesh_terms: D010832:6-Phytase / Q000494:pharmacology*; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition / Q000187:drug effects*; D015519:Bone Density / Q000187:drug effects; D001862:Bone Resorption; D002645:Chickens / Q000254:growth & development*; D004032:Diet / Q000662:veterinary; D004926:Escherichia coli / Q000201:enzymology*; D005658:Fungi / Q000201:enzymology; D008297:Male; D008460:Meat / Q000592:standards; D010758:Phosphorus / Q000008:administration & dosage / Q000172:deficiency* / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D010758:Phosphorus; D010832:6-Phytase