Cereal grains contain almost two-third of the P that is present in phytate form. Phytate possesses anti-nutritive properties as it binds other nutrients like amino acids and carbohydrates. Birds are unable to use P bound with phytate complex. The phytate P is excreted into the environment causing pollution. To compensate requirements expensive inorganic P sources like DCP and rock phosphate are used in poultry diets, which ultimately increase the ration cost. Exogenous phytase is capable of degrading phytate into lower esters having less chelating capacity. Commercially phytase enzymes are being added in the poultry diets to hydrolyze the phytate P that can replace the expensive inorganic P addition. In the industry, phytase is being added in the poultry diets at 500 FTU/kg. Use of phytase at this rate still leaves some gap. Keeping this thing in view present study was planned to use the super dose of phytase from two different sources (Buttiauxella and E.coli) to minimize the anti-nutritive aspects of phytate and use the phytate P at maximum. For this purpose 35 day feeding trial was conducted to evaluate the effect of super dosing of phytate from two different origins on growth performance, phosphorus utilization and carcass characteristics of broilers. For this in total, 672 one-day old broiler chicks were randomly selected& assigned to 8 dietary treatments, each having 3 replicates of 28 birds. One group was reared on positive control diet formulated according to the Hubbard strain recommended guides with adequate P without any phytase addition. Second group was offered NC diet (deficient in Av.P). While other six diets were formulated with three levels (500, 1000, 1500 FTU/kg) of E.coli and Buttiauxella origin supplemented in NC diet. The FI, BWG and FCR were recorded at the end of each week. At the end of experiment n=3 birds per replicate were selected randomly, weighed and slaughtered to estimate plasma P, ileal digestibility of P, tibia ash, organ weight and dressing percentage. The data collected were analyzed using analysis of variance (ANOVA)
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technique in a Completely Randomized Design (CRD) and means were be compared through Duncan’s multiple range test (DMR) (Duncan 1955) by using SAS (version 9.1; SAS Inst. Inc., Cary, NC).
Results of the experiment revealed that FI, BWG and FCR was higher 48%, 11% and 64.5% respectively in phytase supplemented diet best treatment T8, when compared to the NC. Phytase supplementation had no effect on organ weights. Organ weight was higher in diet low in NPP. Phytase supplementation had no effect on gizzard weight even at higher doses. Similarly phytase supplementation had positive effects on bone mineralization. Phytase addition in the diets improved tibia ash, Ca and P% at all levels (P <0.01). Plasma P level was significantly increased at higher level of phytase. The AIDC of P was linearly increased by phytase supplementation. Considering the economics phytase supplemented diets at higher level 1500 FTU/kg were most economical when cost of feed calculated to attain 1kg of live weight.
From this experiment it can be concluded that phytase supplementation at higher dose than the standard ensures the maximum break down of phytate P and reduce its anti-nutritive aspects apart from the source of phytase used in the experiment. Dietary inclusion of phytase at super dose economically generates the bio-available P and reduces the P load in the environment improve growth performance, and bone mineralization.
To replace the highly expensive phosphorus sources super dose of phytase can be used instead of standard dose. It can replace the expensive source of inorganic P and economically can generate more profit. Optimum level of phytase in the diet need to be reevaluated to replace inorganic P to some extent, minimize the anti-nutritive aspects of phytate and reduce P load in the environment.