title: Performance of commercial laying hens fed various phosphorus levels, with and without supplemental phytase.
abstract: A 17-wk study was conducted to evaluate the effects of supplementing laying hen diets with a commercially produced microbial phytase. Hy-Line W-36 pullets (21 wk of age) were randomly allocated to 1 of 10 diets in a factorial arrangement of five levels of nonphytate phosphorus (0.1 to 0.5% NPP) and two levels of phytase (0 and 300 U/kg feed). Dietary metabolizable energy, protein, and calcium were maintained at 2,816 kcal/kg, 16.6%, and 4%, respectively. Criteria evaluated included egg production, feed consumption, egg weight, egg specific gravity, mortality, and various bone quality parameters. Feeding 0.1% NPP without supplemental phytase decreased egg production (hen-housed) 8.1% over the entire study and 29.6% over the last 4 wk, relative to other diets without supplemental phytase. Similarly, feed consumption of hens fed 0.1% NPP without phytase decreased 5.8% over 17 wk and 13.0% over the last 4 wk. Egg production and feed consumption were maintained at the level of other treatments without phytase when the 0.1% NPP diet was supplemented with phytase (82.1% and 82.4 g per hen per d, respectively). Egg weights and egg specific gravity decreased and mortality increased when hens consumed 0.1% NPP without phytase. Supplementing the 0.1% NPP diet with phytase completely corrected these adverse effects. No deficiency symptoms were observed in hens fed diets containing 0.2 to 0.5% NPP. Phytase supplementation of these diets gave no further improvements in performance.
authors.affiliation: Department of Poultry Science, Auburn University, Alabama 36849, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Gordon
authors.forename: D A
authors.initials: DA
authors.lastname: Roland
mesh_terms: D010832:6-Phytase / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002645:Chickens / Q000254:growth & development* / Q000502:physiology; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000502:physiology; D004531:Eggs / Q000032:analysis; D005260:Female; D010058:Oviposition / Q000187:drug effects / Q000502:physiology; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D013046:Specific Gravity
chemical_list: D016226:Phosphorus, Dietary; D010832:6-Phytase