In vitro and in vivo evaluation of thyme (Thymus vulgaris) essential oil as an alternative for antibiotic in quail diet1.

The thyme (Thymus vulgaris) essential oil was assessed as antibiotic growth promoter replacement in quail chick diet and in vitro test. In total, 250-d-old Japanese quail chicks (mixed sex) were allocated into 5 dietary treatments of 5 replications (6 females and 4 males in each cage with the size of 40× 90× 25 cm) under a completely randomized design. The dietary treatments were included the control diet, control diet without any additive, control diet plus 100 ppm flavophospholipol as an antibiotic growth promoter, control diet plus 200 ppm TVE, control diet plus 300 ppm TVE, and control diet plus 400 ppm T. vulgaris essential (TVE) oil. Feed intake, BW gain, feed conversion ratio (FCR), organs weight, morphology of intestine, serum lipids, and microbial population were measured on day 35. Lipid oxidation of stored muscle tissue was measured by TBARS test. GC-MS assay, DPPH method, and well diffusion method were evaluated for determination of components, antioxidant, and antimicrobial properties, respectively. FCR improved significantly in 400 ppm TVE compared with 200 and 300 ppm TVE (P < 0.05). The serum triglyceride decreased significantly in both sexes receiving 400 ppm TVE compared with control. Villi height increased significantly in duodenum accompanied by decreasing crypt dept at all TVE levels compared with control and antibiotic. The breast muscle tissue of quail fed on 300 and 400 ppm TVE reduced the rate of oxidation during refrigerated storage compared with control. Thymol was the main component (35.40%) of the thymus oil. The considerable antioxidant activity of TVE was identified by IC50 of 58.48 µg/mL. Moreover, zones of growth inhibition of Gram-positive bacteria and Escherichia coli were numerically greater in different doses of TVE than antibiotics. Therefore, The TVE is suitable alternative component for antibiotic growth promoters by dosing consideration. However, it is possible that antibiotic resistance would increase for these natural compounds along the time.

Effect of pennyroyal, savory and thyme essential oils on Japanese quail physiology.

An experiment was conducted to show the effects of different levels of pennyroyal, thyme and savory essential oils dietary supplementation on performance, organs weight, intestinal morphology, and serum lipids in quails. A total of 550 day-old Japanese quail chicks were allocated into 11 dietary treatments of 5 replications (10 birds in each cage) under a randomized experimental design. The treatments were a basal diet (Control), or 3 levels (200, 300, and 400 ppm) of thyme essential oil (TO), or 3 levels (200, 300, and 400 ppm) of savory essential oil (SO), or 3 levels (200, 300, and 400 ppm) of pennyroyal essential oil (PO) added separately to the basal diet, or also the basal diet supplemented with 100 ppm of flavophospholipol. Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured weekly and calculated totally for 35 d. The organs weight and morphology of intestine parts of one bird from each cage were measured on 35 d. At the same day, blood samples were collected and cholesterol and triglyceride values were separately determined for male and female quails. Although the addition of different levels of essential oils in quail's diet did not affect BWG, a significant decline in FI was observed in the group supplemented with 400 ppm of TO. At the same time, FCR significantly improved (P < 0.05) in the same group as well as in the group supplemented with the antibiotic. However, the organs weight was not significantly affected by the experimental treatments. Nevertheless, villi height of duodenum, jejunum and ileum was significantly increased and crypt depth was significantly decreased in the quails fed diets supplemented with different levels of TO and SO. The values of serum triglycerides decreased in both sexes in the groups that received diets supplemented with different levels of essential oils whereas the values of cholesterol decreased only in males of the essential oils supplemented groups. From the present observations it can be concluded that thyme and savory essential oils can improve FCR by decreasing FI through boosting the absorption of nutrients in intestine. These plant essential oils can replace antibiotic growth parameters without having any adverse effect on quail's health with thyme essential oil exerting the most effective activity.