Abstract
The study was conducted to determine the effects of supplemented thyme oil extract and thyme water extract, the water soluble fraction of thyme extract, on fattening performance, blood parameters, oxidative stress and DNA damage in Japanese quails. Two hundred sixteen chicks were divided into four groups: control (no antibiotic or thyme extracts (I), fl avomycin (II), thyme oil extract (III) and thyme water extract (IV). Groups II and III received 1 g/kg fl avomycin as an antibiotic and 2.5 ml/kg thyme oil extract, respectively. Birds in group IV received 100 ml/l of thyme water extract in their drinking water. There were no signifi cant differences in liveweight between the treatment groups, but feed intake differed (P<0.01) at 0-5 weeks of age. Results showed that thyme extracts decreased feed consumption during the experiment. Similarly, the survival rate differed signifi cantly (P<0.01) between groups; the lowest was in antibiotic group. The levels of plasma cholesterol, triglyceride, high density lipoprotein, very low density lipoprotein and alkaline phosphates were similar in the four treatments. The highest rate of total oxidant status and total antioxidant response were found in group III, the lowest rate of DNA damage in the thyme oil (III) and thyme water extracts (IV) groups. It was concluded that supplementing thyme extract products in the diet of quails at the doses studied does not lead to a negative effect on the growth performance of the birds. Supplemented antibiotic caused an elevation in the oxidative stress index and in DNA damage.
Highlights
As anti-microbial growth promoters, antibiotics have played a significant role in greatly increasing world poultry meat production
There were no significant differences in LW or liveweight gain (LWG) between the group means during the experiment
The feed conversion ratio (FCR) did not differ significantly when the experimental period was considered as a whole, that of group III and IV tended to be better during weeks 0-3 and 4-5
Summary
As anti-microbial growth promoters (flavomycine, avilamycine, salinomycine, avoparcin, bacitracin, virginamycine, etc.), antibiotics have played a significant role in greatly increasing world poultry meat production. Due to their side effects and the increased resistance of pathogen microorganism resulting from their use, antibiotic application has been restricted. Humans receive exposure to antibiotic residues when consuming poultry products (Tajick and Shohreh, 2006) For these reasons, some poultry producers have voluntarily removed most or all of the antibiotics from their chicken feeds. European Union has tightly regulated the use of antibiotics in chicken diets and antibiotics are restricted in the diets as growth promoter These regulations have forced breeders to find alternatives to antibiotics. Some studies have indicated that various plant extracts can improve feed conversion ratio (FCR), increase carcass quality and decrease the mortality rate (Parlat et al, 2005)
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