اثر سطوح مختلف عصاره میکروجلبک کلرلا ولگاریس بر عملکرد در جوجه‌های گوشتی مواجه با تنش گرمایی

The aim of this study was to compare the levels of chlorella vulgaris microalgae extract with additives on performance, carcass characteristics and blood biochemical metabolites in heat-stressed broilers. This experiment has been done using 280 one day-old Ross 308 broiler chicks for 6 weeks. This experiment has been done in completely randomized design with 7 treatments and 4 replicates. Experimental treatments were including: 1- control; 2- diet containing 0.2 g/Kg chlorella extract; 3- diet containing 0.4 g/Kg chlorella extract; 4- diet containing 100 mg/Kg vitamin E; 5- diet containing prebiotic; 6- diet containing probiotic; 7- diet containing antibiotic. Heat stress program applied from 25-42 d.Treatment 2 caused an increase of feed intake and weight gain in comparison to other treatments (P<0.05). Treatment 3 showed the lowest conversion ratio in comparison to other treatments (P<0.05). Concentration of glucose, protein, albumin and HDL were increased with consumption of treatment2 in comparison with other treatments. The most and the least concentration of cholesterol, triglyceride and VLDL was observed in control and treatment 2, respectively. Weight of empty carcass and proventriculus had the most increase in treatments 2 and 3 (P<0.05). Generally, chlorella in concentration of 0.2 g/kg can be a suitable substitution for other additives specially antibiotics in order to improve the performance of boilers.