Precipitated bone phosphate in broiler chick diets

Day-old Cobb x Cobb broiler chicks were housed in battery brooders for 21-day feeding periods during two experiments. Dietary treatments consisted of a corn-soybean starter feed (.37% total; .14% nonphytin phosphorus) supplemented with 0, .05, .10, .15, or .28% phosphorus in the form of dicalcium phosphate, precipitated bone phosphate, or a mixture of soft and precipitated phosphates (each providing 50% of the phosphorus addition). Total dietary calcium was held constant at .90%. Comparable dietary phosphorus from precipitated bone and the soft-precipitated mixture supported body weights statistically equivalent to those of dicalcium phosphate treatments. Tibia ash results at suboptimal phosphorus levels, with one exception, indicated statistically equal utilization from the soft-precipitated combination. Slope-ratio techniques using tibia ash and total nonphytin phosphorus intake established the bioavailability of phosphorus from precipitated bone was 120% when dicalcium phosphate was the standard. The data indicate that precipitated bone phosphate for broilers was fully equivalent in performance to dicalcium phosphate. Providing one-half the supplemental phosphorus from both soft phosphate and precipitated bone seemed to be an acceptable method of meeting practical phosphorus requirements.