Aims: To evaluate the effect of garlic oil and turmeric extract on rumen fermentation and methane emission using an in vitro gas production technique. Study Design: Completely randomized design. Place and Duration of Study: Department of animal science, Faculty of agriculture, Ferdowsi University of Mashhad, between November 2012 and June 2013. Methodology: Treatments were: control (no additives); 10 mg/L of cultural fluid of monensin (MO) as a positive control; 20, 40 and 80 mg/L of cultural fluid of garlic oil (GA20, GA40 and GA80 respectively); 20, 40 and 80 mg/L of cultural fluid of turmeric extract (TU20, TU40 and TU80 respectively). All treatments were incubated for 96 h and gas production was recorded by a pressure transducer at 2, 4, 6, 8, 12, 24, 48, 72 and 96 h of incubation. At 24 h post incubation, pH of cultural medium and methane production were determined. Results: Supplementation of MO and GA80 resulted in a significant reduction in total gas production compared with the control. Furthermore, addition of garlic oil at 80 mg/L strongly decreased methane production during 24 h post incubation (43% lower than the control). Mid and high concentrations of turmeric extract (TU40 and TU80) caused to increase in vitro dry matter disappearance (IVDMD) in comparison with the control. Partitioning factor (PF = mg DM disappeared/ ml gas produced after 24 h incubation) and pH of the cultural medium were higher using MO, TU20 and GA80 compared with that of the control. Lower extent of gas production (b) and gas production rate (c) were observed in MO and GA80 compared with those of the control. Conclusion: Present data indicated that using natural additives might alter rumen fermentation pattern as observed in methane emission from a mixed diet.

Keywords