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Improving rumen microbial fermentation profile with natural active ingredients.

M. E. Rodriguez-Prado


Improving rumen microbial fermentation profile with natural active ingredients.
R. Temmar1, M. E. Rodriguez-Prado*1, G. Forgeard2, C. Rougier2, S. Calsamiglia1. 1Animal Nutrition and Welfare Service, Univeristat Autonoma de Barcelona Bellaterra, Spain, 2Techna France Nutrition Coueron, France.

Different doses of essential oils were screened to select those able to increase propionic and/or butyric and decrease acetic acids using an in vitro batch fermentation system. Treatments were control (CTR), monensin (MON, at 1.25 and 12.5 mg/L) and 13 essential oils from: cassia, anise star, geraniol, lemongrass, limonene D-natural and thyme (at 80, 300 and 750 mg/L); tea tree and coriander seed (at 40, 150 and 375 mg/L); capsicum oleoresin and black pepper (at 0.4, 3 and 7.5 mg/L); garlic (at 30, 120 and 300 mg/L); and turmeric and ginger (at 10, 40 and 150 mg/L). Treatments were added to 50 mL of a 1:1 buffer: rumen fluid medium with 0.5g of a 50:50 forage to concentrate diet under anaerobic conditions and starting pH of 6.6. The experiment was done in triplicate in 2 independent periods. After 24 h, samples were taken for pH, volatile fatty acids and ammonia-N concentration determinations. Effects were analyzed using the PROC MIXED procedure of SAS. The majority of essential oils had no effect at low doses except for garlic and lemongrass. Garlic at 30, 120 and 300 mg/L tended to increase (P < 0.10) propionate and decreased (P < 0.05) the acetate-to-propionate ratio. Lemongrass at 80 mg/L tended to increase propionate (P < 0.10) and decreased (P < 0.05) the acetate-to-propionate ratio. Anise star and thyme (P < 0.05) at 300 mg/L and coriander seed at 150 mg/L (P < 0.10) increased the proportion of butyrate. Capsicum at 3 mg/L, coriander seed at 150 mg/L and thyme at 750 mg/L decreased (P < 0.05) ammonia-N concentration, but the rest of essential oils did not change the ammonia-N concentration. Results confirm the ability of some essential oils to modulate microbial fermentation in a direction consistent with higher propionate molar proportion, and lower acetate molar proportion, the acetate-to-propionate ratio and ammonia-N concentration without changing total VFA in effective doses between 30 and 750 mg/L depending on essential oils.

Keywords: essential oils, rumen microbial fermentation.