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This study investigated the effect of inclusion of dietary oligosaccharides, onion peel, and an essential oil blend (EOB; containing anise, clove, oregano, cedarwood, and ginger in the ratio 4:2:2:1:1) individually and in combinations in the total mixed ration of dairy cattle on in vitro gas production (GP), dry matter disappearance (DMD), fiber fraction disappearance, and total and individual volatile fatty acid (VFA) production. EOB was used at 200 µL g-1 of feed while the other additives were administered at 3% of the feed on a dry matter basis. The in vitro batch culture technique was used for this experiment and the design was a completely randomized design with 12 treatments replicated eight times. The total GP at 24 h was significantly (p < 0.0001) reduced by the inclusion of EOB-containing additives in the total mixed ration. The lowest gas volume was recorded for the treatment containing mannanoligosaccharide + EOB while the highest value was recorded for sole onion peel treatment. The EOB treatment had the lowest methane production while onion peel alone had the highest values for the greenhouse gas parameters. The inclusion of EOB individually and in combination with the oligosaccharides reduced (p < 0.05) propionate and increased acetate molar proportions, with the highest acetate and lowest propionate noted for the galacto-oligosaccharide and onion peel mixture treatment. Inclusion of the additives evaluated in this study had positive effects on rumen fermentation and digestibility indices with a potential for abatement of greenhouse gases when EOB is present individually or in combination with the oligosaccharides. [ABSTRACT FROM AUTHOR]

This study evaluated the synergistic effects of prebiotics containing galacto-oligosaccharides (GOS) and/or mannan oligosaccharides (MOS), essential oil blend (EOB), and onion peel (OPE) on fermentation characteristics using the rumen simulation technique (RUSITEC) system. Three rumen-cannulated, non-lactating Holstein Friesian cows were the inoculum donors. The substrate used for the study was a total mixed ration (TMR), which consisted of corn silage, alfalfa hay, and concentrate at 6:2:2, respectively. Sixteen fermentation vessels were randomly allotted to four treatments with four replicates each over a 9-day period in a completely randomized design. The treatments assessed include: control [TMR only], GEO [TMR + GOS + EOB + OPE], MEO [TMR + MOS + EOB + OPE], and OLEO [TMR + OLG + EOB + OPE]. OLG comprises GOS and MOS in equal proportion. EOB was included at 3 µL/g, while OPE, GOS, MOS, and OLG were added at 30 mg/g TMR. Results showed that pH, gas volume, effluent volume, and ammonia-N were not affected (p > 0.05) by the different additives. Similarly, greenhouse gas (GHG) emissions and nutrient digestibility were not affected by the treatments. Compared to the control, total volatile fatty acids (VFA) were decreased (p < 0.05) by 14.8, 10.8, and 8.5% with GEO, MEO, and OLEO inclusion, respectively, while the molar proportion of acetate was increased (p = 0.011) by 3.3, 1.1, and 3.8% with GEO, MEO, and OLEO inclusion, respectively. MEO increased isobutyrate (p = 0.001) and branched chain VFA (p = 0.013) contents; however, GEO and OLEO inclusion reduced them. Overall, the interaction of EOB, OPE, GOS, and/or MOS did not affect nutrient digestibility or GHG emissions but reduced VFA production. Further research is recommended to assess the dose effect of the additives on GHG emissions and VFA production; and to determine the long-term effects of these interventions on the rumen microbiome and animal performance. [ABSTRACT FROM AUTHOR]

This study investigated the combined impact of essential oil blends (EOBs) and fumaric acid (FA) on ruminal fermentation in dairy cows using the rumen simulation technique (RUSITEC) system. Three rumen-cannulated, non-lactating Holstein Friesian cows served as inoculum donors. The substrate, a total mixed ration (TMR), comprised corn silage, alfalfa hay, and a concentrate mix in a 3:1:1 ratio. The four treatments evaluated were Control (TMR without additives), EFA1 (TMR + EOB1 + FA), EFA2 (TMR + EOB2 + FA), and EFA3 (TMR + EOB3 + FA). Sixteen fermentation chambers were randomly assigned to the treatments, each with four replicates, following a completely randomized design during a 9-day experimental period. EOBs and FA were added at 10 µL/g feed and 3% of TMR, respectively. After a 4-day adaptation, samples were collected for 5 days. Results revealed that EFA1 significantly reduced (p = 0.0351) CH4 emissions by 60.2% without negatively impacting dry matter disappearance, fiber fraction digestibility, pH, or gas volume. All EFAs increased (p < 0.001) the propionate molar proportion and decreased (p < 0.001) the acetate-to-propionate ratio. EFA2 decreased (p < 0.05) the acetate proportion by 3.3% compared to the control. In conclusion, EFA1 is recommended as an effective nutritional intervention to mitigate CH4 emissions and optimize ruminal fermentation in dairy cows. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Essential oils (EO) and fumaric acid (FA) are known for their ability to reduce greenhouse gas (GHG) emissions in ruminant animals. This study aimed to investigate the combined impact of essential oil blend (EOB) and FA (EF) on in vitro fermentation, total gas and volatile fatty acid (VFA) production and GHG emissions of a calf feed in a 24 h batch culture study. Rumen-cannulated black Angus beef cows (n = 3) served as inoculum donors. The calf feed contained 910, 5.8, 70.9, 792, 111, 72 g/kg dry matter (DM), fat, ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL), respectively. The EOB contained equal proportions of ginger, anise, peppermint, oregano and thyme. FA was added at 3% along with EOB at 10, 20, 30 and 40 µL/g calf feed. Five treatments evaluated were Control (without additives), EF10, EF20, EF30, and EF40. Results showed that pH and digestibility of DM, NDF, ADF were not significantly (P > 0.05) affected by the EF treatments (Table 1). ADL digestibility decreased linearly (P < 0.001) with increasing EF dosage. EF40 increased (P < 0.05) cellulose digestibility by approximately 11% compared with EF10. Total gas, methane and carbon dioxide production decreased (linear, quadratic, P < 0.001) with EF inclusion (Table 2). Ammonia concentration decreased linearly (P = 0.009) with increasing EF dosage, while hydrogen sulfide gas was not affected. EF inclusion reduced (P < 0.001) total VFA, acetate but increased propionate and butyrate proportion (Table 3). In conclusion, the combination of EOB and FA effectively mitigated GHG emissions without compromising nutrient digestibility in calves. Therefore, incorporating EOB at 10 µL/g and FA at 3% in calf feed is recommended as an effective nutritional strategy to reduce GHG emissions in calves. [ABSTRACT FROM AUTHOR]