Dietary phosphorus levels during growth of brown egg type replacement pullets

Caged Sex-Sal (DeKalb Warren) replacement pullets were fed diets containing .30%, .35%, or .41% available phosphorus from 0 to 20 weeks of age; in a second study pullets were fed the above levels plus a level of .25% available phosphorus from 2 to 20 weeks of age. Some of the pullets were fed diets restricted by 11 to 16% from 8 weeks of age. Reducing the dietary phosphorus did no harm weight gain, feed intake, feed conversion efficiency, bone ash or total calcium and inorganic phosphorus levels in plasma. There was a very small but significant reduction in weight gain and feed intake when .30% or .35% available phosphorus was fed from 0 to 4 weeks of age, but this difference disappeared at the later ages. With the nonstimulatory lighting schedule used, plasma phosphorus decreased markedly in the latter phase of the studies at all levels of dietary phosphorus and thus represented a nondietary age effect. These results show that dietary available phosphorus for cage, brown egg type pullets on full or restricted feeding programs can be decreased to a level as low as .25% from 2 to 20 weeks, and .30% from hatching to 20 weeks without adverse effect.