مطالعه سیستم ایمنی و صفات لاشه جوجه‌های گوشتی تغذیه شده با جیره‌های دارای مکمل اسیدهای آلی و آنزیم فیتاز

An experiment was conducted to evaluate the effects of organic acids and phytase enzyme supplementation on immune system and carcass characteristics of broiler chickens. The experiment was done in factorial arrangement 2×2×2 based on completely randomized design with 8 treatments, 5 replicates and 12 chicks in each to 42 d of age. Diets including natural vinegar (0 and 2%), citric acid (0 and 1%) and phytase enzyme (0 and 500 U phytase/kg of feed). All the birds were vaccinated against Newcastle disease by lasota vaccine via aye drop in 11 and 23 days. In order to study the immune system situation, blood samples of two birds of each replicate was taken in 42 day. After serum separation, the IgG of NDV was detected by HI test. One birds of each replicate (five birds of each treatment) randomly selected and were killed to evaluate lymphoid organs weigh and carcass characteristics at 42 day. The analysis of results showed that addition of vinegar and phytase significantly increased the relative weight of bursa (P<0/05). Interaction effect of citric acid with vinegar and with phytase enzyme significantly increased the relative weight of bursa (P<0/05) also vinegar significantly increased the relative weight of spleen (P<0/05). Phytase significantly increased the abdominal fat (P<0/05) while citric acid and interaction effect of citric acid with vinegar significantly decreased the abdominal fat (P<0/05). In current study treatments hasn’t any effect on internal organs relative weight (P>0/05).