This study was conducted to evaluate the effects of rosemary essential oil (REO) on feed digestibility, ruminal fermentation and blood metabolites of Ghezel sheep. Four male sheep with average body weight 46 ± 2.0 kg were used in a 4 × 4 Latin square design. Treatments were control (no REO added), 100 mg d -1 of REO (low), 200 mg d -1 of REO (medium) and 400 mg d -1 of REO (high). Sheep were fed the 4 diets for 4 periods of 21 days (14 days as adaptation and 7 days for sample collection). The results showed that digestibility of dry matter, neutral-detergent fiber, aciddetergent fiber and crude protein were not affected by REO feeding (p > 0.05). The concentration of ammonia-N across sampling times was lower (p < 0.05) at low REO dosage compared with control. The molar proportion of acetate and butyrate across sampling times were lower at low REO dosage compared with control (p < 0.05). Total volatile fatty acids (VFA) concentrations at 4 h after morning feeding were reduced (p < 0.05) by adding 100 mg of REO d -1 to diet compared with the control, whereas medium REO dosage increased (p < 0.05) total VFA concentrations at 4 h post feeding compared with the control. The addition of REO had no effect on total protozoa counts across sampling times (p > 0.05). Supplementation with REO had no effect on plasma concentrations of glucose, triglyceride, cholesterol, total protein and albumin (p > 0.05). The results of this study indicate that, although a medium dose of REO may have positive effect on rumen fermentation, a low dose of REO may have adverse effects on ruminal fermentation.
1. The aim of this study was to evaluate various levels of Satureja khuzistanica essential oil (SKEO) on performance and physiological parameters of broilers fed on wheat- or maize-based diets. 2. Treatments consisted of two cereals (maize- or wheat-based diets) and three levels of SKEO)0, 250 and 500 mg/kg). 3. Feed intake (FI) and body weight gain (BWG) decreased in broilers fed on the wheat-based diets compared to the control diet. Dietary supplementation of 500 mg/kg SKEO increased FI and BWG. Dietary SKEO supplementation was effective in improving FI and BWG only in wheat-based diets and was effective in improving feed conversion ratio (FCR) in both diets. 4. Dietary supplementation of 500 mg/kg SKEO caused a significant decrease in plasma cholesterol and triglycerides. Also, plasma low-density lipoprotein concentration was decreased in broilers fed on 250 and 500 mg/kg of SKEO. Plasma cholesterol levels in birds fed on the wheat-based diets were lower than in those fed on maize-based diets. 5. Dietary supplementation of 500 mg/kg SKEO increased caecal population of Lactobacillus and reduced total bacterial and Escherichia coli count. Caecal population of Lactobacillus decreased in broilers fed on the wheat-based diets. 6. Digesta viscosity was increased in broilers fed on the wheat-based diets and decreased in broilers fed on 500 mg/kg SKEO compared to the control diet. Dietary SKEO supplementation was effective in reducing digesta viscosity values only in wheat-based diets. 7. Villus height of the duodenum and jejunum decreased in broilers fed on the wheat-based diets. Dietary supplementation of 500 mg/kg SKEO increased villus height and villus height-to-crypt depth ratios and decreased crypt depth of the duodenum compared to the control diet. 8. It can be concluded that dietary SKEO supplementation was effective in improving FI, BWG and FCR values in wheat-based diets.
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