تأثیر جایگزینی جو به جای ذرت ، با و بدون استفاده از آنزیم در تغذیه جوجه های گوشتی

Barley consumption is limited in broiler chicken diet due to their β. glucanas polysaccharide content. The application of synthetic enzymes in poultry diet can increase the barley content. The purpose of this experiment is to study the effect of enzyme supplement-β-glucanas on the performance of broiler chickens, percentage of abdominal fat, intestine weight and economic evaluation of production of one kilogram of meat in diets including different levels of barley and corn. Five hundred forty-one-day-old commercial broiler chickens (Arian) were divided into 45 groups, 12 chickens per group Each one of the 15 experimental diets, in which barley was substituted for corn at levels 0, 25, 50, 75 and 100% with 2 levels of enzymes (0.025 and 0.05%) was fed to 3 groups of chickens for 49 days. All diets were isoenergetic and isonitrogenous. Plant oil was used to make diets isoenergetic. The results showed that the rate of weight increase of broiler chickens decreased as each level of free enzyme barley was replaced at 0.83, 6.08, 12.9, 16.1 %, respectively. The weight gain of the chickens fed with diets including a large amount of barley and 0.05% enzyme didn’t have any significant difference (P < 0.01) with the control group. The chickens fed with diet including barley and 0.025% enzyme didn’t have any significant difference either (except at 75% and 100% barley replacements). Enzyme supplementary at 0.025% and 0.05% levels (especially at 0.05%) caused significant improvement (P < 0.01) in food consumption and feed conversion ratio of chickens fed with diets including barley. Analysing the carcass of these chickens showed that the enzyme used at both levels, especially at 0.05 %, caused a significant decrease (P < 0.01) in abdominal fat (3.62% vs. 4%). It was also seen that the weight of chickens fed with enzyme decreased significantly (P < 0.01) in comparison with chickens fed with free enzyme barley diets (9.57% vs. 14.81 %). The economic calculation results of producing meat in this experiment pointed out that using barley and corn caused reduction in production expenses. The general results of this study showed that barley with enzyme is a suitable replacement for enzyme and further that 0.05% level of enzyme is better than 0.025% level due to its performance and better economic results.