Phosphorus. 1. Effect of breed and strain on utilization of suboptimal levels of phosphorus in the ration.

Single Comb White Leghorn cockerel chickens were able to utilize suboptimal levels of phosphorus in the ration more efficiently than broiler cockerel chickens as measured by growth, livability, and bone calcification. The superiority of the Leghorn-type over the broiler-type in utilizing suboptimal levels of phosphorus was accentuated by high levels of calcium in the ration. Among broiler strains the Athens Canadian Randombred cockerel chicken utilized suboptimal levels of phosphorus more efficiently than the two commercial strains tested. The Single Comb White Leghorn chickens showed higher retention values for calcium, phosphorus, and phytin phosphorus than the broiler strain. High calcium levels in the ration caused a much lower retention of phytin phosphorus by both Single Comb White Leghorn and broiler chickens.