title: Influence of cage density and prior dietary phosphorus level on phosphorus requirement of commercial leghorns.
abstract: Two studies were conducted to determine whether cage density and prior dietary nonphytate P (NPP) level affect hens' P requirements. In Experiment 1, hens were housed at three cage densities (300, 400, and 600 cm2 or 46.5, 62.0, and 93.0 inches2/hen) and fed four levels of NPP (0.15, 0.25, 0.35, and 0.40%) for 6 wk to determine the effect of cage density on the P requirement. Egg production (EP), feed consumption (FC), egg weight (EW), and egg specific gravity (ESG) were measured to evaluate performance. Cage density influenced EP within Week 1 (P < 0.01), and during Weeks 5 and 6, there was a cage density x NPP-level interaction (P < 0.05). At 300 cm2, EP was more severely affected by 0.15 and 0.25% NPP than at 400 and 600 cm2. A linear decrease (P < 0.001) in FC was observed because of decreased NPP. Hens at 300 cm2 consumed 4 g less feed/hen per d than hens at 400 cm2. A linear decrease in EW was observed as the NPP level decreased (P < 0.01) from 0.25 to 0.15%, and there was no effect of cage density. Experiment 2 was conducted to determine the effect of prior dietary P levels on time required to create a P deficiency. Hens fed 0.4% NPP were divided into two groups and fed 0.25 and 0.4% NPP for 4 wk. At the end of 4 wk, hens fed 0.25% NPP were further divided into three groups and were fed diets containing 0.09, 0.25, and 0.30% NPP for an additional 6 wk. Hens fed 0.4% NPP were divided into three groups and fed diets containing 0.09, 0.4, and 0.45% NPP. Reduction of NPP from 0.4 and 0.25% to 0.09% reduced EP by 8.5 and 6.8%, respectively, within 3 wk. Prior NPP levels had no influence on time required to create a P deficiency in terms of EP. Reduction of NPP from 0.4 and 0.25% to 0.09% reduced (P < 0.05) FC. A decline in FC occurred 2 wk earlier in hens previously fed 0.4% than those fed 0.25% NPP. This result indicates that hens fed 0.4% NPP became P deficient more quickly than hens fed 0.25%. We concluded that cage density and prior NPP level affect the hen P requirements or time required to create a P deficiency.
authors.affiliation: Department of Poultry Science and Alabama Agriculture Experiment Station, Auburn University, 36849, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Sohail
authors.forename: M M
authors.initials: MM
authors.lastname: Bryant
authors.forename: S K
authors.initials: SK
authors.lastname: Rao
authors.forename: D A
authors.initials: DA
authors.lastname: Roland
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002645:Chickens / Q000378:metabolism / Q000502:physiology*; D004435:Eating / Q000187:drug effects; D004531:Eggs / Q000032:analysis / Q000592:standards; D005260:Female; D006799:Housing, Animal; D009751:Nutritional Requirements; D010058:Oviposition / Q000187:drug effects; D010758:Phosphorus / Q000097:blood / Q000172:deficiency*; D016226:Phosphorus, Dietary / Q000008:administration & dosage* / Q000378:metabolism; D011156:Population Density; D011897:Random Allocation; D013046:Specific Gravity; D013997:Time Factors
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus