Non-phytate phosphorous requirements of pullets from 3 to 6 weeks of age and carryover effects of phosphorous deficiency at 18 weeks of age

The non-phytate phosphorous (nPP) requirement of 3 to 6 week old laying hen pullets was determined using body weight gain (BWG), mortality corrected feed conversion ratio (FCRm), tibia ash percent (TAP) and tibia ash weight (TAW). Potential carryover effects of early nPP deficiency at 12 and 18 wk were determined with the same parameters. A total of 1,008 Lohman LSL-Lite 3-week-old pullets were distributed across 42 cages and assigned 1 of 7 treatments (0.15, 0.22, 0.29, 0.36, 0.43, 0.49, and 0.56% nPP). There were 24 birds per cage and they were fed ad libitum. Pullets remained in respective treatment groups and phase-fed common diets from 6 to 18 wk. Body weight and FCRm were determined every 3 wk. At 6, 12, and 18 wk of age, 6, 2, and 2 pullets per pen, respectively, were euthanized for tibia ash determination. Data were analyzed using ANOVA in JMP Pro 16.0 and means were separated using Student’s t-test (P ≤ 0.05). Regression analysis from 3 to 6 wk was completed using BWG, FCRm, TAP, and TAW as response variables. The nPP requirement was 0.17% nPP for BWG, 0.14% nPP for FCRm, 0.16% nPP for TAP, and 0.14% nPP for TAW using linear broken line regression. The 0.15% nPP treatment from 3 to 6 wk reduced BW and TAW (P ≤ 0.05) at 6 wk of age. With at least 6 wk of recovery, measured parameters were not different starting at 12 wk (P > 0.05). The nPP requirement for pullets from 3-6 wk of age was 0.16% to maximize bone ash percent with no carryover effects noted by 18 wk of age when adequate nPP was fed from 6 to 18 wks.