Effects of Different Essential Oil Blends and Fumaric Acid on In Vitro Fermentation, Greenhouse Gases, Nutrient Degradability, and Total and Molar Proportions of Volatile Fatty Acid Production in a Total Mixed Ration for Dairy Cattle

Abstract

The present study evaluated the inclusion of fumaric acid and essential oil blends (EOBs) containing anise, cedarwood, clove, cumin, eucalyptus, garlic, ginger, lavender, lemongrass, nutmeg, oregano, and peppermint at different proportions on in vitro dry matter (DM) disappearance (DMD), fiber fraction disappearance, the efficiency of microbial production, and the total volatile fatty acids (VFAs). Ten treatments without (control treatment) or with different EOB/fumaric combinations were used in the study with eight replicates. The EOB inclusion level was 200 μL/g of feed (total mixed ration, (TMR)) while fumaric acid was administered at 3% of the TMR (DM basis). The highest DMD, in vitro true degradable DM, partitioning factor (PF24), and in vitro apparent degradable DM were recorded for the fumaric only treatment and the control. Neutral detergent fiber disappearance was reduced with the inclusion of EOB/fumaric combinations. The production of microbial mass and undegraded DM were higher (p < 0.001) for all EOBs and EOB and fumaric treatments. The inclusion of EOB and fumaric combinations reduced (p < 0.001) the total gas production, methane, and ammonia, with a higher PF24 value noted for EOB3 treatment. The inclusion of individual EOB1 containing garlic, lemongrass, cumin, lavender, and nutmeg in a ratio of 4:2:2:1:1 or combined with fumaric acid yielded the highest propionate concentration across all treatments. We concluded that EOBs decreased methane production and nutrient degradability with better results with the individual EOB1 or EOB1/fumaric combination, which showed a potential enhancement in energy production.

A Mixture of Prebiotics, Essential Oil Blends, and Onion Peel Did Not Affect Greenhouse Gas Emissions or Nutrient Degradability, but Altered Volatile Fatty Acids Production in Dairy Cows Using Rumen Simulation Technique (RUSITEC)

“…The mechanisms behind the potential synergistic effects of essential oils and prebiotics/plant extracts are not fully understood but may involve complementary modes of action. Combinations leveraging complementary modes of action show promise for improving ruminant production efficiency while mitigating environmental impacts [17,21]. Essential oils can directly inhibit certain rumen microbial groups, while prebiotics and plant compounds selectively promote the growth of beneficial microbes [13,22,29].…”

“…Several studies have investigated the potential synergistic effects of combining essential oils, fumarate, prebiotics, and other feed additives on rumen fermentation and GHG mitigation [21,39,40]. Yatoo et al [41] reported a 14% reduction in CH 4 production in EOB treated groups compared to the control group.…”

“…Patra and Yu [22] reported that combining essential oil compounds (eugenol and carvacrol) with fumarate resulted in greater reductions in CH 4 production compared to when each was used individually in an in vitro system. Similarly, Alabi et al [17] and Ike et al [21] reported that blends of essential oils along with fumaric acid decreased total VFA, CH 4 , and hydrogen sulfide (H 2 S) to a greater extent than EOB alone.…”

“…The EO blend consisted of garlic, lemongrass, cumin, lavender, and nutmeg at 4:2:2:1:1, respectively. The EOB was selected based on its efficacy to reduce CH 4 production from previous studies [17,21]. The four treatments were investigated using a completely randomized design with four replicates: The OLG treatment consisted of GOS and MOS at 1:1 (v/v).…”

“…The combination of different feed additives has gained interest as a strategy to potentially achieve synergistic effects on rumen fermentation, nutrient utilization, and mitigation of environmental impacts like GHG emissions [17,21]. Patra and Yu [22] reported that combining essential oil compounds (eugenol and carvacrol) with fumarate resulted in greater reductions in CH 4 production compared to when each was used individually in an in vitro system.…”