title: Effects of phosphorus level and phytase in broiler breeder rearing and laying diets on live performance and phosphorus excretion.
abstract: The effects of a reduced dietary nonphytate phosphorus (NPP) level and inclusion of phytase on broiler breeder performance and P concentrations in the litter and manure were investigated. Ross 308 broiler breeder pullets and Ross 344 cockerels were placed sex-separate in a blackout growing house and fed standard starter and grower diets to 9 wk of age. At 10 wk of age, 4 treatments (A, B, C, D) were assigned to each of 4 floor pens of 68 pullets and 1 pen of 50 cockerels. From 10 to 21 wk, treatments A to D contained 0.37, 0.27, 0.27, and 0.17% NPP, respectively, with 300 phytase units (FTU)/kg of phytase added to treatments B and D. At 21 wk of age, birds were photostimulated and transferred to a two-thirds slat-litter breeder house with 16 pens of 60 pullets and 6 cockerels. A laying diet was fed from 22 to 64 wk and NPP levels of treatments A to D were adjusted to 0.37, 0.27, 0.19, and 0.09%, respectively, and phytase addition to treatments B and D was increased to 500 FTU/kg. Analysis of the litter from growing pens showed no effect on litter total P when phytase replaced 0.1% of NPP. However, decreasing the dietary NPP by 0.1% without phytase reduced the litter total P by 18%. Water-soluble P (WSP) and the WSP:total P ratio decreased when the grower dietary NPP level was reduced to 0.17% with added phytase and was correlated with litter moisture levels in growing pens. During the laying period, a reduction in NPP from 0.37 to 0.09% with added phytase reduced both the manure total P and WSP by 42%. Hen-day egg production was highest on the lowest NPP diet with phytase, but fertility decreased when the dietary NPP was reduced below 0.37%. Results showed that phytase inclusion in a broiler breeder laying diet at the expense of all added P from dicalcium phosphate reduced the manure total P and WSP concentrations by 42%, with no effect on the number of chicks produced per hen housed.
authors.affiliation: Department of Poultry Science, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC 27695-7608, USA.
authors.forename: P W
authors.initials: PW
authors.lastname: Plumstead
authors.forename: H
authors.initials: H
authors.lastname: Romero-Sanchez
authors.forename: R O
authors.initials: RO
authors.lastname: Maguire
authors.forename: A G
authors.initials: AG
authors.lastname: Gernat
authors.forename: J
authors.initials: J
authors.lastname: Brake
mesh_terms: D010832:6-Phytase / Q000494:pharmacology*; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001682:Biological Availability; D002645:Chickens / Q000254:growth & development*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D005243:Feces / Q000737:chemistry*; D005260:Female; D008297:Male; D010058:Oviposition / Q000187:drug effects; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*; D015430:Weight Gain / Q000187:drug effects*
chemical_list: D010758:Phosphorus; D010832:6-Phytase