A Triple Response Method for Determining Biological Value of Phosphorus Sources with Young Turkeys

A NUMBER of studies have been conducted to determine the availability of phosphorus or biological value of phosphorus sources for chicks and poults. Several research avenues have been followed in the evaluation of phosphorus sources. In spite of these research efforts, or perhaps because of them, there is presently no standard phosphorus assay technique or procedure. Commercial feed manufacturers at times may have difficulty recognizing real differences in phosphorus sources relative to availability or biological value. REVIEW OF PHOSPHORUS BIOASSAY RESEARCH Researchers have tended to disagree on three or four main factors pertinent to phosphorus bioassays. These factors include: (1) type of basal diet, (2) response criterion or criteria used, (3) specie of animal or bird, and (4) length of assay period. It is interesting to note how these factors have varied in previous studies. Gillis et al. (1948) used a purified diet composed largely of corn starch, dried blood …