title: Minimum phosphorus requirement of one-cycle and two-cycle (molted) hens.
abstract: In experiment 1 (one cycle), hens were fed diets containing 0.10, 0.115, 0.125, 0.135, 0.15, or 0.45% available P (AP) from 40 to 56 wk of age, with the last diet being a positive control. Egg production, egg mass, and BW were reduced (P < 0.05) by all lower AP levels except 0.15% AP when compared with the 0.45% AP treatment. In the second experiment (two cycles with a molt), hens were initially fed diets containing 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, or 0.45% AP from 21 to 63 wk of age. Diets containing 0.10, 0.12, and 0.14% AP were terminated at 35, 39, and 50 wk, respectively, due to low egg production and increased mortality. Hens fed 0.16% AP also had significantly lower production performance than hens fed 0.45% AP during the first cycle. Hens on the 0.16 to 0.45% AP treatments were induced molted at 64 wk of age by 10 d of feed removal. The hens were then returned to the same AP layer diet they had been fed from 21 to 63 wk. For the 68 to 108 wk postmolt second-cycle period, hens fed the 0.16 to 0.20% AP diets (166 to 209 mg/d) had significantly lower egg production, egg mass, and feed efficiency than hens fed 0.45% AP. The results of our study indicated that first-cycle hens required approximately 0.18% AP or 198 mg AP/hen per day, and molted hens in their second cycle had a requirement that was greater than 0.20% AP or 209 mg AP/hen per day.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Snow
authors.forename: M W
authors.initials: MW
authors.lastname: Douglas
authors.forename: K W
authors.initials: KW
authors.lastname: Koelkebeck
authors.forename: A B
authors.initials: AB
authors.lastname: Batal
authors.forename: M E
authors.initials: ME
authors.lastname: Persia
authors.forename: P E
authors.initials: PE
authors.lastname: Biggs
authors.forename: C M
authors.initials: CM
authors.lastname: Parsons
mesh_terms: D000375:Aging; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D004032:Diet; D004531:Eggs; D005260:Female; D018978:Molting; D009751:Nutritional Requirements; D010058:Oviposition; D016226:Phosphorus, Dietary / Q000008:administration & dosage*
chemical_list: D016226:Phosphorus, Dietary