Response of Two Breeds of Chickens to Graded Levels of Dietary Phosphorus

BREEDS of chickens may differ in utilization and metabolism of various nutrients (Nesheim and Hutt, 1962; Thornton and Whittet, 1962; Daghir and Balloun, 1963; Donovan, 1965; Yoshida et al., 1966). This may be the reason for a wide variation (Peeler, 1963) in the recommendations in the dietary phosphorus requirements. Although Lillie et al. (1964) concluded that phosphorus requirement did not differ between strains of chickens, they used relatively high levels of phosphorus and strains with similar growth rates which might have prevented differences in response to certain criteria from being exhibited. The purpose of the present experiments was to study the effects of low levels of dietary phosphorus on growth, feed efficiency, bone-ash, mortality, and plasma inorganic phosphorus of two breeds of chickens of both sexes. PROCEDURE Two breeds of chickens were studied in a 3 × 2 × 2 × 2 factorial experiment involving three levels of added dietary…