Effects of Different Level of Phytase on Broilers Performance and Body Status of Phosphorus

Discussion Committee: 
Prof. Jamal Abo Omar
Dr. Rateb Aref
Prof. Adnan Shquire
Prof. Jamal Abo Omar
Rabie Ihsan Ahmad Sabha
This experiment was conducted to investigate the effect microbial phytase supplementation on broilers performance, nutrient digestibility, visceral organ mass, carcass cuts and body status of Ca and P. a total of 200 day-old Cobb 500 chicks were used in the experiment. Birds were partitioned into five experimental groups of 40 birds in each. Each treatment was composed of 4 replicates with 10 birds in each. The control group was fed a commercial starter and finisher diet. The second treatment was a phosphorus deficient diet, while the third, fourth and fifth treatments were fed a phosphorus deficient diets plus the microbial phytase. Phytase enzyme was incorporated at levels 1000, 2000 and 3000 PU/kg feed for the last three treatments, respectively. At the last week of experiment, three birds from each replicate were used in metabolic trial. However, at time of termination of the experiment, the same birds were killed for carcass cuts, visceral organ mass and tibia ash content investigations. The experiment lasted for 42 days. Results of the experiment showed that addition of phytase to P-deficient diets improved (P<0.5) broilers performance with impact starting from the beginning of the fourth week of the feeding trial. However, it has no effect on feed intake. Feed conversion ratio and dressing percent were increased (P<0.05) in birds fed P-deficient diets supplemented with phytase. Phytase supplementation had no significant effect on both male and female carcass cuts compared to birds fed the low P diets. Variable effects of phytase supplementation at different levels on gastrointestinal tract and its associated organs of both male and female broilers were observed. Male and female birds fed P-deficient diets incorporated with phytase enzyme at different levels had more (P<0.05) ash, Ca and P compared to birds fed the P-deficient diet. Also results of this investigation showed that phytase enzyme increased (P<0.05) the digestibility of dry matter, crude protein and ash. Phytase supplementation decreased the excreta content of Ca and P indicating the improvement of the retention of these two minerals. The overall results indicated that incorporation of phytase in broiler ration could be economically feasible as significant portion of P in diets could be reduced.
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