الفهرس 
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Abstract
In a feeding trial the impact of dietary fortification of an exogenous mono component protease enzyme with or without its matrix values (ME 31.5 Kcal, CP 0.84%, Methionine 0.018%, lysine 0.05%, threonine 0.034%) on growth performance traits, Crude protein digestibility, serum parameters, selected immune parameters, total counts of ileal clostridia species, carcass traits as well as duodenal histomorpholoigcal picture were studied. The economic feasibility of this enzyme supplementation was also evaluated. A total of 300 day old chicks (Cobb500) were randomly assigned to five separate floor pens equal experimental groups with three replicates (20 birds /replicate). Birds were fed either on corn–soybean meal basal diets (starter- grower and finisher) without any supplementation (G1) and served as control group, or basal diets to which protease enzyme was added on top at a rate of 200 ppm (G2), however birds in (G3) were fed on the basal diets to which protease was added at the same inclusion level but subtracting the whole matrix value of the enzyme, meanwhile birds in (G4) were fed on the fortified basal diets after subtracting only the metabolizable energy matrix value of the enzyme while birds in (G5) were reared on the fortified basal diets after subtracting only the crude protein as well as amino acids matrix value of the enzyme. The experiment was extended for five weeks.
The results revealed that, bird in groups 2 and 4 significantly ( P≤ 0.05) surpassing all groups regarding weight gain, and FCR, also these groups showed significant ( P ≤ 0.05) improvement in better dressing % and only numerical increase in the BMY. Results also indicated that G2 (protease on the top) and G4 (Low ME values) showed a significant elevation of CP digestibility and showed a significant (P≤ 0.05) reduction of total ileal clostridia species counts. Numerical non-significant improvements in immune responsiveness were noticed in all protease supplemented groups indicated by increased levels of HI against ND vaccine after 10th days post vaccination in comparison with control group (G1). In addition, G2 showed an increase in villus height and villus to crypt ratio, in comparison to the other experimental groups. On the other hand, none of the examined serum parameters were affected by any of the dietary treatments. On the basis of the above cited findings, it might be concluded that the broiler chickens respond positively to exogenous dietary supplementation of mono-component protease enzyme at the abovementioned level and method of incorporation and it can be used safely and economically of their diets.