Submitted to: Canadian Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2012
Publication Date: 8/8/2012
Citation: Tekippe, J.E., Hristov, A.N., Heyler, K.S., Zheljazkov, V.D., Ferreira, J.F.S., Cantrell, C.L., Varga, G.A. 2012. Effects of plants and essential oils on ruminal in vitro batch culture methane production and fermentation. Canadian Journal of Animal Science. 92:395-408. Interpretive Summary: Plants and essential oils (EO) from plants that are naturalized to, or can be successfully grown in North America, were evaluated in in vitro screening experiments as potential inhibitors of enteric methane production in ruminants. A total of 88 EO and 14 plants were tested. Ruminal inoculum from lactating dairy cows, containing microorganisms responsible for fermentation and production of methane, was collected 2 hours before animal were fed. Incubation was conducted in glass bottles containing a feeding mixture composed of alfalfa hay, corn starch, and soybean meal, a buffer solution and ruminal inoculum. Incubation was anaerobically conducted at 39 degree C for 6 hours. Parallel incubations were conducted to evaluate the effect of plants and EO on the 24-h neutral detergent fiber degradability. Essential oils were tested at four levels (as final medium concentration): 0 (control), 10, 50, and 100mg/L. Plants were tested using the same procedure, except that a portion of the alfalfa hay in the incubation bottles was replaced with the plant material to be tested (at 312.5, 1,250, 2,500, and 5,000 mg/L, final incubation medium concentration). At the end of the incubations, total gas and methane production, volatile fatty acid concentration, and fiber degradability were measured. Compared with the control, 2 of the EO increased acetate concentration (8 to 10%), 11 EO increased propionate concentration (9 to 23%), 10 EO increased butyrate concentration (24 to 29%), and 3 EO (dill weed, lavender, and basil accession#7) reduced methane production (20 to 30%;). Four EO reduced and one increased 24-h fiber degradability. Three of the plant increased acetate concentration (8 to 12%), 2 increased propionate concentration (16%), and one (oregano) decreased methane production (31%). Eight of the plants increased fiber degradability at various inclusion levels. Overall, these results indicated that some EO, or EO-producing plants could have a potential anti-methanogenic effect in the rumen, but these in vitro observations need to be confirmed in vivo and in long-term experiments.
Technical Abstract: In this study, plants (14) and essential oils (EO; 88) from plants that are naturalized to, or can be successfully grown in North America were evaluated in a batch culture in vitro screening experiments with ruminal fluid as potential anti-methanogenic additives for ruminant diets. Essential oils were tested at four inclusion levels: 0 (blank), 10, 50, and 100 mg L(-1) and plants were tested at 312.5, 1250, 2500, and 5000 mg L(-1) final incubation medium concentration. Compared with the blank, two of the EO increased acetate concentration (8 to 10%), 11 EO increased propionate concentration (9 to 23%), 10 EO increased butyrate concentration (24 to 29%), and three EO reduced methane production [20 to 30%; Anethum graveolens (dill weed oil), Lavandula latifolia, and Ocimum basilicum #7 accession]. Four EO decreased and one increased neutral detergent fiber (NDF) degradability. Three plants increased acetate concentration (8 to 12%), two increased propionate concentration (16%), and one (Origanum vulgare) decreased methane production (31%). Eight of the plants increased NDF degradability at various inclusion levels. Overall, these results indicate that some EO, or EO producing plants could have a potential anti-methanogenic effect. Further research is needed to verify these results in vivo in long-term experiments.