Factors Affecting the Chick’s Requirement for Phosphorus

DURING investigations to develop a practical method for measuring availability of phosphorus supplements, various factors which affect the young chick’s requirement for phosphorus were studied. The NRC publication on Nutrient Requirements of Poultry (Bird et al., 1966) places the phosphorus requirement for starting chickens at 0.7% of the diet, with the further provision that at least 0.5% of the total feed should be inorganic phosphorus. This requirement is in good agreement with those found by Lillie et al. (1964), Twining et al. (1965). and Mehring and Titus (1964) in their extensive studies with broiler strain chicks on practical diets. Almquist (1954) placed the requirement, in the presence of ample vitamin D, at 0.45% for the first 4 weeks. Early attempts to study the biological value of inorganic phosphates were reviewed by Gillis et al. (1954). They used a purified diet to study phosphorus sources of moderate or high availability, and…