The phosphorus needs of young broiler chicks in relationship to dietary nutrient density level.

A study was conducted to determine if the dietary need of the broiler chick for available phosphorus remained in constant ratio to the energy content of the diet. Corn-soybean meal diets were prepared with dietary energy levels of 2970, 3190 and 3410 M.E. kcal./kg. with inorganic P levels from 0.13 to 0.63% in increments of 0.10%. Least squares analyses were used to determine points of maximum response for body weight tibia ash, and efficiency of feed utilization through 28 days of age. Small but consistent reductions were observed in available phosphorus energy ratios as the dietary energy level increased. For maximum response chicks needed the following levels of inorganic phosphorus per 1000 M.E. kcal./kg. at 2970, 3190 and 3410 M.E. kcal./kg., respectively: (a) for body weight, 0.159, 0.153, 0.144%; (b) for tibia ash, 0.170, 0.168, 0.151%; (c) for feed utilization, 0.153, 0.145, 0.138%.