Effect of Level and Source of Phosphorus and Different Calcium Levels on Productivity and Phosphorus Utilization by Laying Hens

THE availability of plant phosphorus to laying hens has been a matter of controversy for the past few decades. Lowe et al. (1939), Krieger and Steenbock (1940), Spitzer et al. (1948), Gillis et al. (1949, 1957), and Matterson et al. (1946) have repeatedly reported that phosphorus extracted from plant material was poorly utilized by chicks and rats. McGinnis et al. (1944) suggested that phosphorus from plant sources had lower availability for chicks than other sources. This was in contrast to data by Singsen et al. (1950), who demonstrated by using P32 isotope as a tracer that phytin phosphorus moved freely about the body and participated in reactions requiring phosphorus. Harms et al. (1962) and Vandepopuliere et al. (1961) reported high availability of plant phosphorus for growing chicks. Recently, Singsen et al. (1967) reported no difference in the ability of various sources of phosphorus in supporting egg production. Furthermore, they indicated…