Abstract

Abstract
Background
The efficacy of replacing conventional dicalcium phosphate (DCP) with nano-hydroxyapatite (NHA), with or without phytase, in the diets of broiler chickens was investigated over a 35-day feeding period.
Methods
A total of 250 one-day-old Ross 308 broiler chicks (as hatch) were randomly allocated into four different dietary groups, each with five replicates (12 chicks/replicate). The control (CON) group was fed the basal diet only, whereas two treatment groups were fed diets containing 0.1% NHA (NHA 0.1%) or 0.2% NHA (NHA 0.2%) without DCP or phytase. A fourth group (Phy + NHA 0.1%) was fed 0.1% NHA combined with phytase 5000 FTU/g (0.01%), also without DCP. Growth performance, carcass traits, tibia mineralization, mineral excretion, and blood biochemical indices were evaluated.
Results
Dietary supplementation of 0.1% NHA with 0.01% phytase 5G showed significant improvements (p ≤ 0.05) in body weight, weight gain, feed conversion ratio (FCR), and European Production Efficiency Factor (EPEF) compared to other groups. Moreover, tibia Ca and P % were maintained (p > 0.05) as a ratio of 2:1 among all groups, indicating that NHA could improve Ca and P bioavailability in bone. However, Ca (p = 0.002) and P (p = 0.003) excretion were significantly reduced in all NHA-fed groups compared with the control. Serum calcium concentration increased (p = 0.009) in birds receiving NHA diets, while the combination of 0.1% NHA with 0.01% phytase 5G resulted in the greatest enhancement of serum phosphorus (p = 0.001) compared with the NHA-only groups.
Conclusion
Conclusively, replacing DCP with 0.1% NHA, particularly when supplemented with phytase, enhanced growth performance, improved feed efficiency, and increased P utilization while preserving bone mineralization in broiler chickens. These findings support NHA as a promising alternative mineral source in poultry nutrition.

Key words: Nano-hydroxyapatite, Phytase, Tibia, Phosphorus excretion, Serum calcium