ARS | Publication request: Effects of herbs and essential oils on in vitro batch culture ruminal fermentation

Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2011
Publication Date: N/A

Technical Abstract: Medicinal herbs and essential oils were evaluated in a batch culture in vitro screening experiment as potential anti-methanogenic additives for ruminant diets. A total of 88 essential oils and 14 herbs were tested. Rumen inoculum enriched with particle-associated microorganisms was collected from a lactating dairy cow, 2 h before feeding. Incubation was conducted in serum bottles containing 1 g of a feed mixture (0.7 g alfalfa hay, 0.2 g corn starch, and 0.1 g solvent-extracted soybean meal), 1 ml of essential oils (10, 50, and 100 mg/L, final medium concentration), 19 ml of McDougall’s buffer with 5 g/L glucose and 2.5 g/L acid-hydrolyzed casein, and 20 ml of ruminal inoculum. Bottles were then flushed with CO2 and incubated at 39 deg C for 6 h. Corresponding 50 ml tubes were incubated for 24 h for NDF degradability analysis. Herbs were tested using the same procedure, except a portion of the alfalfa hay was replaced with 12.5, 50, 100, and 200 mg of plant material (air-dry basis), and NDF was tested using the DAISY apparatus. Blanks and monensin (5 mg/L, final medium concentration) were also incubated. At the end of the incubations, total gas and methane production, VFA and ammonia concentration, and NDF degradability were measured. Treatment by application level interactions were not significant for any of the essential oil treatments. Two of the essential oils increased acetate production, 12 increased propionate production, 10 increased butyrate production, 3 reduced methane production (by 20 to 30%), and 2 decreased ammonia production. With the herbs, 1 increased acetate production, 2 increased propionate production, 1 decreased methane production (by 30%), and 1 decreased ammonia production. Eight of the herbs increased NDF degradability at various inclusion levels. Overall, these results indicated that some essential oils and medicinal herbs may have a significant effect on ruminal fermentation in vivo.