Effect of immobilized fungal phytase on growth performance and bone traits of broilers fed with low dietary calcium and phosphorus

AIM: The aim of this study was to investigate the effects of phytase which was laboratory produced by Aspergillus foetidus on the growth performance, mineral retention, and bone traits of broilers fed with low dietary calcium and phosphorus. MATERIALS AND METHODS: The extracellular phytase enzyme secreted into the crude filtrate was concentrated by ammonium sulfate precipitation to obtain an activity of 500 phytase units (FTU). A total of 90 1-day-old chicks (Cobb 500) were randomly divided into three treatment groups with five replicates having six birds each. Dietary treatment, T1, was with 0.45% non-phytate P (NPP) during starter and 0.40% during finisher phase with 1% Ca. Dietary treatment, T2, had 0.37% NPP during starter and 0.32% in finisher phase with 1% Ca and supplemental lab phytase at 500 FTU/kg. Dietary treatment, T3, was similar to T2 with a lower Ca of 0.8%. RESULTS: There was no significant difference among the dietary treatments with regard to body weight gain, feed intake, feed conversion ratio, and Ca retention (p>0.05). However, a significant improvement in retention of P by birds was observed in phytase supplemental groups T2 and T3 (p<0.05). Dry weight of tibia (2.58-2.78 g/kg live weight) and ash content (39.7-41.8%) was comparable among treatments. A similar trend was observed for bone Ca, P, and Mn content. CONCLUSION: The study indicated that 500 FTU/kg phytase can be effectively supplemented in a broiler diet with low phosphorus (0.37% in starter and 0.32% NPP in finisher diet) and low calcium (0.8% in diet) for better growth performance and with successful replacement of dietary P by 0.08 % and reduced P excretion into the environment in broiler chicken.