Non-phytate phosphorus requirements of egg laying pullets from 0 to 3 weeks of age and carryover effects of phosphorus deficiency at 6, 9, 12, and 18 weeks of age

The objectives were to determine the non-phytate phosphorus (nPP) requirement in 0 to 3- wk-old laying hen pullets using body weight (BW), mortality corrected feed conversion ratio (FCRm), tibia ash expressed as weight (TAW) and percentage (TAP), and total body bone mineral content (BMC) and to understand the longer term effects of early phosphorus deficiency on pullets over time. Hy-Line W36 pullets were distributed across 42 cages resulting in 7 dietary treatments (0.15, 0.22, 0.29, 0.36, 0.43, 0.49, and 0.53% nPP and 1.0% Calcium) fed across 6 replicate cages of 30 chicks. After 3 wk, all birds were switched to common corn-soybean meal diets that contained 0.49, 0.48, 0.45, 0.48% nPP and 1.0, 1.0, 1.0, 2.5% Ca from 3 −6, 6-12, 12−15, 15−18, respectively. Pullets were euthanized at 3, 6, 9, 12, and 18 wk of age for BMC and tibia ash determination. Linear and quadratic broken-lines were used to estimate nPP requirements of 0 to 3-wk-old pullets. The nPP requirement was 0.31% nPP for BW; 0.27% nPP for FCRm; 0.31% for TAP; 0.31% for TAW; 0.32% for BMC using linear broken line analysis. Low concentrations of dietary nPP fed over the 0 to 3 wk period reduced BW at 6 wk (P ≤ 0.05), but after 9 wk no response criteria were different among the dietary nPP treatments (P > 0.05). These data indicate that the nPP requirement for pullets from 0 to 3 wk is between 0.27 and 0.32% nPP dependent on response criteria used, and that there are few to no long-term effects of low phosphorus feeding when pullets are provided an adequate nPP diet over time.