Effect of combination of citric acid and microbial phytase on digestibility of calcium, phosphorous and mineralization parameters of tibia bone in broilers
This experiment was conducted to evaluate the combined effects of citric acid (CA) and microbial phytase (MP) on digestibility of calcium, phosphorus and mineralization parameters of tibia bone in broilers chicks. A total of 360 Ross-308 male broiler chicks were used in a completely randomized design with a 3 × 2 factorial arrangement (0, 2.5 and 5% CA and 0 and 500 FTU MP). Four replicate of 15 chicks each were fed dietary treatments including: (i) P-deficient basal diet [0.2% available phosphorus (aP)] (NC); (ii) NC + 500 FTU MP per kilogram of diet; (iii) NC + 2.5% CA per kg of diet; (iv) NC + 2.5% CA + 500 FTU MP per kg of diet; (v) NC + 5% CA per kg; and (vi) NC + 5% CA + 500 FTU MP per kg of diet. The content of calcium, phosphorus and length of tibia bone and digestibility of calcium and phosphorus was evaluated. The results show that interaction effect of CA × MP on tibia calcium content and low available phosphorus diets was significant (p<0.01). Adding of CA to P-deficient diets increased tibia phosphorus content of broilers when compared with the control group (p<0.01). Adding MP to P-deficient diets based on corn-soybean meal, cause increased digestibility of calcium, phosphorus and also, length of tibia in broilers (p<0.01). Also, adding of CA to broiler diets deficient in available phosphorus, significantly increased digestibility of phosphorus (p<0.01) and length of tibia (p<0.001) when compared with the control group. From this study, it could be deduced that adding MP to low available phosphorus diets can cause improvement of utilization of phytate phosphorus. Also, adding CA as a chelator to diet can improve tibia mineralization parameters in broilers.
Key words: Available phosphorus, calcium, citric acid, microbial phytase.