A total number of 175. day-old unsexed "Arbor Acres" broiler chicks were
conducted to study the effects of phytase supplementation on growth performance.
efficiency at energ,y utilization, carcass characteristics, and tibia measurements ot
broiler chicks fed energy-deficient diets. Chicks were divided into five experimental
groups, each of 35 cttieks (7 replicates of each group) to receive one of the five
experimental diets (control, 75 kcal ME less than control, 150 kcal ME less than
control, 75 kcal ME less than control + phytase, 150 kcal ME less than control +
phytase). The feeding period was extended tor 49 days. The results obtained are summarized as follows: t-Broiler chicks fed energy-deficient diets recorded lower values (Pat live
body weight; weight gain and depressed feed conversion ratio and relative
energy efficiency compared to control diet. 2-Addition of phytase to the energy-deficient diets significantly increased live body
weight (LBW). body weight gain (8WG) and improved feed conversion ratio and
relative energy efficiency. 3-No significant effects were found on percenlages of dressing, liver, gizzard, heart, abdominal fat, total edible parts, breast meat, and thighs meat. 4- Tibia measurements (OTW, Tl, TW, TBS and tibia content of ash, Ca and P) of
birds ted the control diet refonmulated with phytase did not differ from those of birds
fed energy-deficient or control diets. In general, it could be recommended that reformulation enerqy-defcient diets by
phytase supplementation could restore body weight gain and improve feed conversion
ratio.