Essential Oil Blends with or without Fumaric Acid Influenced In Vitro Rumen Fermentation, Greenhouse Gas Emission, and Volatile Fatty Acids Production of a Total Mixed Ration

Abstract

The growing interest in improving rumen fermentation and mitigating methane emissions necessitates the use of essential oil blends (EOB) and fumaric acid (FA). This study evaluated the synergistic effect of four EOB with or without FA supplementation on in vitro dry matter digestibility, greenhouse gas emission, and total volatile fatty acid production using inoculum from three rumen-cannulated Black Angus beef cows. The study was arranged in a 4 × 2 + 1 factorial design to evaluate the effects of the four EOB and two FA levels on a total mixed ration (TMR). The EOB dosage was 100 µL while FA was added at 3% of total mixed ration. The EOB × FA interaction (p < 0.05) influenced the dry matter, neutral detergent fiber, and hemicellulose degradabilities. All the EOB and FA (EFA) treatments decreased (p < 0.001) the dry matter degradability compared to the control (TMR substrate only). The EFA4 treatment reduced the neutral detergent fiber and hemicellulose degradabilities compared to the control. The ruminal pH was influenced (p < 0.001) by both the EOB and FA inclusion, and the EOB × FA interaction was significant. The microbial mass was higher (p < 0.001) in the EFA1, EFA4, and EOB4 compared to the control and the EOB3 treatments. The EFA1 and EOB1 produced less (p < 0.001) gas than the control by 29.1 and 32.1%, respectively. Compared with the control, the EFA1 and EOB1 treatments decreased (p < 0.001) methane gas by 90.8% and 86.4%, respectively, while the carbon dioxide was reduced (p = 0.004) by 65.7 and 57.9%, respectively. The EOB × FA interaction was significant (p < 0.001) for the total and individual volatile fatty acid concentrations. The inclusion of FA increased the propionate concentration by 9.5% and decreased (p = 0.02) the acetate concentration by 4%. In summary, the synergistic effect of the EOB and FA offers an effective way to reduce greenhouse gas emission and enhance total volatile fatty acids.

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

“…The nutrient contents of the TMR are shown in Table 1. A detailed procedure on the chemical composition has been previously described by Alabi et al [15]. The dry matter (#930.15) was determined by using the AOAC procedures [23].…”

“…The dry matter (#930.15) was determined by using the AOAC procedures [23]. Nitrogen (N) quantification (#954.01), ether extract (EE; #920.39), and ash content (#942.05) were determined as described previously [15]. The neutral detergent fiber (NDF) was determined according to the procedure of Van Soest et al [24], with alpha amylase and sodium sulfite, while the acid detergent fiber (ADF; #973.18) content was analyzed according to the AOAC method [23].…”

“…Fumarate has been studied for its ability to manipulate rumen microbes and improve the fermentation process in vitro and in vivo [15]. Fumarate functions as a hydrogen acceptor and may be utilized by rumen microorganisms as a propionate precursor [16].…”

“…Fumarate functions as a hydrogen acceptor and may be utilized by rumen microorganisms as a propionate precursor [16]. Fumaric plays a key role as one of the metabolic intermediates of the propionate-succinate pathway, making it an option to increase ruminal propionate production by competing with methanogens for available hydrogen [17], resulting in lower CH 4 production [15]. Li et al [18] reported that fumaric acid reduces CH 4 emissions, total volatile fatty acids (VFAs), and the acetate-to-propionate ratio but increases the propionate concentration.…”

“…There is limited information on the synergy between EOBs and fumaric administration in the diets of dairy cows. Alabi et al [15] observed that EOBs at 100 µL/g and fumaric acid at 3% of the diet reduced DM degradability and CH 4 production but increased the microbial mass, total VFAs, and propionate in an in vitro study with inoculum from beef cattle. Similarly, Lin et al [22] observed that mixing fumarate with an EOB containing mainly clove, oregano, cinnamon, and lemon decreased the concentrations of VFAs and ammonia-N (NH 3 -N), populations of methanogens, and protozoa but increased the propionate proportion.…”