title: Extra-phosphoric effects of superdoses of a novel microbial phytase.
abstract: An experiment was conducted to evaluate the influence of a novel microbial phytase on broiler performance from d 0 to 42 and tibia ash at d 21. Male Cobb 500 broilers (n = 2,016) were fed 1 of 7 experimental diets: positive control (PC) formulated to meet or exceed nutrient recommendations; PC plus dicalcium phosphate (PC+DCP) formulated to provide Ca and P at 0.10% above the PC; PC plus 500 U/kg of microbial phytase (PC+500); negative control (NC) with Ca and P reduced from the PC by 0.16 and 0.15%, respectively; and NC plus 500 (NC+500), 1,000 (NC+1,000), or 1,500 (NC+1,500) U/kg of microbial phytase. Diets were fed in 3 phases from d 0 to 21, d 22 to 42, and d 43 to 49 to 32 birds/pen and 9 replicate pens/diet. From d 0 to 21, broilers fed the NC diet had decreased (P ≤ 0.05) BW gain and tibia ash compared with broilers fed all other diets, except tibia ash in birds fed PC+500. Phytase supplementation at 500, 1,000, or 1,500 U/kg to the NC improved (P ≤ 0.05) BW gain and tibia ash comparable with the PC. Feed conversion ratio (FCR) was improved (P ≤ 0.05) in broilers fed NC+1,500 compared with broilers fed all other diets. From d 0 to 49, growth performance was not influenced (P > 0.05) by diet. However, FCR was improved (P ≤ 0.05) in broilers fed 1,500 U/kg of microbial phytase compared with broilers fed the PC, PC+DCP, and NC. There were no differences in performance or tibia ash between broilers fed the PC or PC+DCP, which would indicate the PC diet was sufficient in Ca and P. Therefore, the improvements in FCR in the NC+1500 may be associated with mitigation of the antinutrient effects of phytate rather than improved P utilization.
authors: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, UK. Carrie.Walk@abagri.com
authors: C L
authors: CL
authors: Walk
authors: M R
authors: MR
authors: Bedford
authors: T S
authors: TS
authors: Santos
authors: D
authors: D
authors: Paiva
authors: J R
authors: JR
authors: Bradley
authors: H
authors: H
authors: Wladecki
authors: C
authors: C
authors: Honaker
authors: A P
authors: AP
authors: McElroy
mesh_terms: D010832:6-Phytase / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D002645:Chickens / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D008297:Male; D010758:Phosphorus / Q000378:metabolism*
chemical_list: D010758:Phosphorus; D010832:6-Phytase