عنوان مقاله [English]
Introduction: Nowadays, there is an increasing interest to use organic compounds in broiler chicken diets instead of antibiotics and other feed additives may cause deleterious effects on the poultry products consumers. Using medicinal plants have different effects on broiler life such as improving feed efficiency, augmentation of immunity, producing more desirable carcass and so on. The goal of this study was to investigate the effect of adding coneflower and thyme alcoholic extracts to diet on performance, carcass characteristics, internal organs weights and also some blood and immunity parameters of broiler chickens.
Materials and methods: One hundred-sixty 1-d-old chickens (male and female) were randomly divided into four treatment groups with four replicates in each, and reared for 42 days. The treatments were: 1- control (basal diet formulated according to Cobb500 nutrients recommendation), 2- adding 0.2% thyme extract into basal diet, 3- adding 0.2% coneflower extract into basal diet, and 4- adding 0.2% of thyme+ 0.2% of coneflower extracts into the respective basal diets; starter (1-10 d), grower (11-23 d) and finisher (24-42 d) that were fed to the birds from the beginning. Experimental plants extracts were collected via UV-extraction method by ethanol followed by the rotary evaporation to eliminate the diluent. All the feeding and vaccination programs of chickens were in accordance with Cobb500 commercial strain recommendations. Feed intake, weight gain and feed conversion ratio of chickens were weekly recorded. At the end of the study, one bird of each replicate was slaughtered for carcass analysis and blood sampling. Blood parameters were assayed via spectrophotometer. Carcass parts and internal organs weights were expressed as a percent of carcass weight. The antibody titers against Newcastle and Influenza diseases were assayed. Data were analyzed as a completely randomized design and the means comparison was performed by least significant different test.
Results and Discussion: Results showed that the effect of treatments on the amounts of feed intake and weight gain of chickens over the study. Feed conversion ratio of chickens was significantly affected by the treatments where the lowest was observed in control group and the highest in coneflower group. Carcass traits (the weights of empty carcass, breast, thighs, abdominal fat and back) and internal organs weights (liver, heart, lungs, intestines and gizzard) were not affected by the treatments. The weights of body organs are basically affected by genetic potential that the used chickens were very close in this sight of view, and weight gain also among groups was not significantly different. Effect of treatments on antibody titers against Newcastle and influenza was significant. The lowest antibody titer against Newcastle and the highest against influenza were observed in thyme group. Both of coneflower and thyme were showed having stimulatory effect on antibody production in poultry, but the different effects observed in the present study may be due to the epidemic of diseases and also the hygienic conditions of the farm. Adding coneflower and thyme into the diet increased the bursa of fabricius weight of chickens than the control, but it had no significant effects on spleen weight. It should be mentioned that the chickens in the present study were vaccinated according to the provider company recommendations and also a coccidiostat compound was used in the diet that they together can obstruct or interrupt on the expected beneficial effects of coneflower and thyme on immune parameters. Adding thyme and coneflower into the diet caused a marked decrease in blood lipids concentrations. One of the desired properties of medicinal plants is lowering the blood’s and carcass’s lipids that was observed in the present study. It is reported that these plants have some components suppressing the lipids synthesis in liver and also other ones effect on lipase enzymes activity in tissues. The treatments had no significant effects on the hematological parameters of chickens. Whereas there were no significant differences in the amount of daily feed intake and weight gain of chickens and also all of the environmental conditions for chicken were the same, therefore none of hematological parameters were affected by the treatments.
Conclusion: Generally, adding coneflower and thyme extracts into the diets of chickens had not significant effects on their growth performance in the overall period of the experiment and carcass traits as well. Using coneflower and thyme extracts in broilers diets has a booster effect on the antibody titer against influenza, while no positive effects were observed for Newcastle disease. Adding coneflower and thyme extracts into the diet of chickens prominently decreased the all types of blood lipids. No synergistic effects were observed between coneflower and thyme extracts wherever they had a significant effect on assayed parameters.