Evaluation of Phosphated Egg Shell and Fertilizer Phosphates in Turkey Starter Diets

Three experiments of 28 days duration were conducted to evaluate phosphated egg shell and fertilizer phosphates as supplemental phosphorus sources. Large White, female poults of the Nicholas strain were used in all studies. The birds were fed a corn-soybean meal basal diet containing 28 percent protein. Phosphorus sources and calcium carbonate were added to furnish the desired levels of Ca and P. Dietary treatments and tap water were given ad libitum and birds were raised in battery brooders with raised wire floors. Bioavailability of phosphorus from two fertilizer phosphates, concentrated super phosphate (CSP) and diammonium phosphate (DAP), was high. Relative biological values for CSP and DAP were 95 and 96 percent, respectively, as compared to 100 percent for mono-sodium phosphate (NaH2PO4 · H2O), the reference standard. The relative biological value of phosphated egg shell was 99.5 and 100.1 percent in two separate experiments. CSP and DAP contained 2.35 to 2.48 percent of fluorine and were somewhat toxic, depressing body weight gain and feed efficiency when fed to supply recommended or higher than recommended levels of supplemental phosphorus. Depressions in body weight gain and feed efficiency were observed in two experiments. High fluorine levels from CSP and DAP apparently did not affect tibia breaking strength and percent tibia ash in these short term experiments. Fluorine content of tibia ash was significantly (P < 0.05) increased with CSP and DAP treatments.