تاثیر افزودن آنزیم به جیره‌ غذایی بر پایه ذرت- کنجاله سویا بر مقادیر انرژی قابل متابولیسم و ابقا ظاهری نیتروژن در جوجه‌های گوشتی

Background: supplementation of exogenous enzyme can improve mtabolisable energy of broiler chicken diets. objectives: this study was conducted to evaluate the effects of supplementation of exogenous enzyme on apparent dm and cp metabolizability, apparent n retention and improvement of amen of broiler chicken diets. methods: a total of 200, one day old male broiler chicks were randomly assigned in completely randomized design, as 4×2×3 factorial arrangement (4×3×2) with 4 me levels (2750, 2850, 2950 and 3050 kcal/kg) supplemented with 2 levels (0 and 450 mg/kg of diet) of an exogenous enzyme, natuzyme –p, in diets of broilers on apparent dm metabolizability, apparent n retention and amen improvement over the starter, grower and finisher phases of growth. results: the apparent dm metabolizability of diets was increased by increasing amen levels (p < 0001) and enzyme addition increased dm metabolizabilityby as much as 1.8 percent (p < 0.0002).the apparent n retention was increased significantly with increasing me levels (p < 0.001). enzyme supplementation improved apparent n retention of diets as much as 2.63 percent (p < 0.0001). the values of amen were improved by the main effects of me levels and enzyme addition (p < 0.0001, p < 0.0027). enzyme supplementation increased mean value of amen as much as 52 kcal/kg. apparent n retention (p < 0.0001) and apparent dm metabolizability (p < 0.0007) was affected significantly by the main effect of phase growth and the highest values of apparent n retention and apparent dm metabolizability was found in grower and starter phases of growth, respectively. two and three-way interaction effects of enzyme supplementation, me levels and growth phase was not significant on amen improvement, apparent dm metabolizability and apparent n retention. conclusion: enzyme supplementation in corn-soybean meal based diet improved apparent dm metabolizability, apparent n retention and amen values.