Effects of Dietary Available Phosphorus Levels and Phytase Supplementation on Performance, Egg Quality and Serum Biochemical Parameters of Hy-Line Brown Laying Hens from 40 to 60 Weeks of Age

This study was performed to evaluate the effects of available phosphorus (AP) levels with or without supplemental phytase on the performance, egg quality, and serum biochemical parameters of laying hens. A total of 540 laying hens (40-week-old) were housed in cages and assigned to 6 dietary treatments with 5 replicates each, for 20 weeks. The treatments consisted of 0.20%, 0.25%, and 0.30% AP diets with or without phytase supplementation. During the 20-week period, egg production was lowest in hens fed the 0.20% AP diet; however, phytase supplementation in the diet completely corrected the adverse effect (P<0.05). No consistent difference was observed in egg production between hens fed the 0.25% and 0.30% AP diets and those fed the 0.20% and 0.30% AP diets with phytase supplementation. Similarly, egg mass was lowest in the 0.20% AP diet-fed group, and no difference in egg mass was observed in the 0.25% and 0.30% AP diet as well as the phytase-supplemented diet groups; however, egg mass was improved in the phytase-supplemented diet groups(P<0.05). Egg quality traits did not differ with dietary treatments. Serum alkaline phosphatase level showed a linear decrease (P<0.05) in the phytase-treated groups with increasing AP levels; moreover, a numerically linear increase (P<0.05) in serum Ca and P levels was observed in the phytase-treated groups. The results of this study indicate that phytase supplementation in the diet of laying hens could increase egg production and may lead to greater mineral absorption.