عنوان مقاله [English]
The addition of various substances such as probiotics and prebiotics and synbiotics and herbs and their extracts as possible alternatives to antimicrobial growth stimulants have positive effects on the host.The aim of this experiment was to investigate the effect of different levels of barley extract and synbiotic on yield, carcass characteristics and blood parameters of Ross 308 broilers. The experiment was conducted in a completely randomized design with 5 treatments, 5 replications and 10 chickens in each experimental unit for a total of 250 one-day-old chickens. Experimental treatments including control (without additive), barley extract 0.1%, barley malt extract 0.2%, barley extract 0.3% and soluble synbiotic in water were tested on broilers for 42 days. Feed-intake, weight gain and feed conversion ratio were recorded in initial, growth, final pahse and throughout the experiment. In order to determine the characteristics of the carcass and measurement of blood parameters, at 42 days of age, two male chickens were selected from each experimental unit and slaughtered after weighing. The results showed that the addition of barley malt extract at the levels of 0.1, 0.2, 0.3% and synbiotic alone on feed intake, weight gain and feed conversion ratio of broilers compared to the control was not significant. Also, adding 0.3% barley malt extract to drinking water caused a significant increase in triglyceride and VLDL-c serum levels of broiler chickens compared to the control (p <0.05), but other levels of malt extract barley and synbiotic had no significant effect on other blood parameters of broilers compared to controls. The present study showed that different levels of malt extract and synbiotic alone could not significantly improve the performance index and carcass efficiency throughout the experiment compared to the control group.