effect of different levels of marigold (calendula officinails) oil extract on performance, blood parameters and immune response of broiler chickens challenged with ccl4

introduction although use of antibiotic as growth promoter in poultry and animal nutrition have led to positive effects, researches indicated that antibiotic residues in animal and poultry products caused resistance of bacteria and fungi strains and a resistance to antibiotics as a treatment tool for human diseases. herbal extracts, probiotics and enzymes are suggested as replacers for antibiotics in animal and poultry nutrition. plants and their active substances with their variety of functions are used as medicinal plants for years to prevent and treat many diseases in human, animal and poultry. oil extracts of marigold has many active substances such as saponins, flavonoids and antioxidants and serve as a strong antioxidant to control free radicals. therefore, the extract of marigold was used to test its curing effects on challenged birds with tetra hydrochloride (ccl4), an inducer for liver damage. material and methods this experiment was conducted to evaluate the effects of marigold oil extracts (moe) on performance, blood parameters and immune response of broiler chickens in a 42-day period. a total of 200 ross 308 male broiler chickens were allocated to five dietary treatments with four replicates of 10 birds each. treatments consisted of 1) control (without marigold extract and ccl4), 2) ccl4, 3-5) 150, 300, and 450 mg/kg marigold oil extract as supplement + ccl4 (1 mg/kg body weight). ccl4 was injected intraperitoneally from 21 to 30 days of age in a 2- day intervals. during this period sodium chloride (0.9%) was added to control group. at day 33, one chick from each replicate of treatments was selected, and their blood and internal organs were used for different bio assays. results and discussion no significant differences detected among treatments for performance. however, the highest and the lowest feed intake at starter and grower periods obtained from the treatments used moe and control groups, respectively (table 2). the highest and the lowest weight gain were also observed for the birds received 300 mg /kg moe + ccl4 and ccl4 groups, respectively. many studies have revealed that phytobiotics had no effect on performance of the birds when marigold, cinnamon and garlic powder were applied as supplements into the diets. the results are in agreement with those of this study. birds fed different levels of moe + ccl4 had higher liver weights than those of birds received only ccl4. however, this effect was not significant. in control group, liver weight was lower (p> 0.05) than that of the birds received ccl4 (1.581 vs 1.451) and moe alleviated the negative effect of ccl4 on this trait (table 5). the relative weight of the thymus at 33 days of age (table 4) and the igg level (table 3) at 28 and 35 days of age in the group received 300 mg/kg of moe + ccl4 were significantly higher (p> 0.05). levels of blood metabolites (sgot and sgpt) were increased when ccl4 was added to the diets (table 5) and moe was able to reduce the negative effects of ccl4. levels of cholesterol and triglycerides were significantly decreased in the birds received moe when compared with those of the birds in positive control group (p< 0.05). moe again was able to decrease the negative effect of ccl4 on blood metabolites of bilirubin, cholesterol, and triglyceride. moe possess hepatoprotective property that might be attributed to its active substances (flavonoids) present in the flower of marigold. plants and plant extracts having flavonoids and phenolic compounds are able to have the most antioxidant properties. the extracts of marigold contain abundant amounts of active biological metabolites of flavonoids and terpenoids and the alleviating effect of moe on organ weights, blood metabolites and immunological indices might be due to these substances. conclusion under the conditions of this study, it was concluded that marigold oil extract at moderate levels is able to decrease the negative effects of ccl4 induced hepatic cell injuries and can be used as a suitable natural antioxidant in poultry nutrition.