in eachfeeding period. The diets fo

in each
feeding period. The diets formulated to lower available
phosphorus levels utilizing either normal or low phytate
corn were mixed and then crumbled (starter diets) or
pelleted (grower and finisher diets). After crumbling or
pelleting, the diets were sprayed with sufficient phytase
to provide 500 U/kg of phytase activity. The enzyme
was mixed with a 10:1 ratio of water as a carrier just
prior to spraying; diets without phytase enzyme were
sprayed with the same amount of water. This procedure
added 0.10% water to each diet. Dicalcium phosphate
addition to the diet supplemented with phytase or
formulated using low phytate corn was reduced approximately
28%, and in the diets formulated with HAP corn
and supplemented with phytase dicalcium phosphate
supplementation was reduced approximately 56%.
Body weights and feed consumption were determined
when the chicks were 21, 42, and 49 d of age.
When the birds were 49 d of age, 15 birds per pen were
identified by having body weights closest to the mean
body weight of the pen. Five birds per pen were
randomly selected from these identified birds and were
bled by cardiac puncture. Whole blood was used to
determine red blood cell counts, hematocrit,
hemoglobin, mean corpuscular volume, mean corpuscular
hemoglobin, mean corpuscular hemoglobin concentration,
white blood cell counts, and differential leucocyte
counts using a model 3500 Cell-Dyn hematology
analyzer5 following the manufacturer’s recommendations.
Serum was collected and the clinical chemistry
analysis of serum levels of calcium, phosphorus, uric
acid, total protein, cholesterol, triglycerides, creatinine,
and the enzyme activities of alkaline phosphatase,
glutamyltransferase, and cholinesterase were measured
using an automated clinical chemistry analyzer6 following
the manufacturer’s procedures.
Five birds per pen were killed by cervical dislocation
and left tibiae were removed, and stored at 6 C. The
bones were thawed, the central diameter was measured,