An experiment was conducted to evaluate the influence of the drying temperature of the di-calcium phosphate (DCP) on its X-ray diffraction patterns (XRD), spatial structure and solubility, retention of calcium and phosphorus, growth performance, tibia mineralization and strength in broiler chickens fed diets supplemented with phytase. A total of 500, 1-d-old Ross 308 female broiler chickens were randomly allocated to a 5 × 2 factorial arrangement and fed diets contained DCPs dried at 5 different temperatures (60, 90, 110, 160 and 200°C) and two levels of phytase enzyme supplementation (0 or 1000 FYT/kg). There were 10 treatments and 5 cages with 10 chicks per each treatment. XRD pattern of DCP showed sharp peaks in lower temperature which indicting good crystallinity of DCP particles. Increasing the drying temperature resulted in amorphous solid with a XRD pattern typical for amorphous solid with reduced peaks height. Field emission scanning electron microscope (FESEM) images revealed considerable agglomeration and clustering of the DCP particles by increasing the drying temperature especially at 160 and 200°C compared to the DCP dried at 60°C. Solubility of DCP in 2 % citric acid (CA) was reduced by increasing the drying temperature linearly (P < 0.01). The solubility of DCPs dried at 60, 90, 110, 160 and 200°C were 96.2, 91.4, 88.1, 82.6 and 78.2 % respectively. Chicks fed diets supplemented with DCP dried at 160 and 200°C had lower BW and higher FCR (P ≤ 0.01) compared to the other chicks fed diet supplemented with DCP dried at 60, 90 and 110°C. Plasma Ca and P concentration was significantly higher (P ≤ 0.01) in chicks fed diets supplemented with DCP dried at 110°C on day 20. At day 30, plasma P concentration was significantly higher (P ≤ 0.01) in chicks fed diets supplemented with DCP dried at 60°C. Phytase supplementation had no significant effect on Ca, P and serum alkaline phosphatase (ALP) activity throughout the experiment. No significant difference in serum ALP activity were found among chicks fed different DCPs, however, intestinal ALP activity was higher (P ≤ 0.05) in chicks fed diets contain DCP dried at 110°C. Intestinal ALP activity was reduced significantly (P ≤ 0.05) by inclusion of exogenous phytase. Birds fed diet contained DCP dried at 60°C had the highest (P ≤ 0.01) level of P retention at both 10 and 32 days of age. Increasing the drying temperature of DCP reduced P retention significantly (P ≤ 0.05). Calcium retention were not affected (P > 0.05). The proximal length and proximal head thickness of femur bone, tibia ash and P content was higher (P ≤ 0.05) in birds fed diets contained DCP dried at 60°C. Tibia breaking strength was reduced in birds fed diets contained DCP dried at 160°C (P ≤ 0.05). In conclusion, the results of this study indeed showed that higher drying temperature of DCP negatively affect its structure and reduced its crystallinity and solubility which was illustrated by XRD diffraction patterns and FESM images.
