Screening for effects of plant extracts and active compounds of plants on dairy cattle rumen microbial fermentation in a continuous culture system

Rumen microbiota succession throughout the perinatal period and its association with postpartum production traits in dairy cows: A review

The transition period for dairy cows usually refers to the 3 weeks pre-calving to the 3 weeks post-calving. During this period, dairy cows undergo metabolic and physiological adaptations because of their susceptibility to metabolic and infectious diseases. Poor feeding management under these circumstances may adversely affect the health and subsequent production performance of the cows. Owing to long-term adaptation and evolution, the rumen has become a unique ecosystem inhabited by a complex microbial community closely associated with its natural host. Dietary components are metabolized by the rumen microbiota, and volatile fatty acids and microbial protein products can be used as precursor substances for synthesizing meat and milk components. The successful transition of perinatal dairy cows includes changes in diet, physiology, and the rumen microbiota. Rumen microbial profiles have been confirmed to be heritable and repairable; however, adverse circumstances affect rumen microbial composition, host digestion and metabolism, as well as postpartum production traits of dairy cows for a certain period. Preliminary evidence indicates a close relationship between the rumen microbiota and animal performance. Therefore, changes in rumen microbes during the transition period and the intrinsic links between the microbiota and host postpartum phenotypic traits need to be better understood to optimize production performance in ruminants.

Effect of nutmeg essential oil (Myristica fragrans Houtt.) on methane production, rumen fermentation, and nutrient digestibility in vitro

The study evaluated the effect of adding of nutmeg (Myristica fragrans Houtt.) essential oil (NEO) as a feed additive on methane production, rumen fermentation parameters, rumen enzyme activity, and nutrient digestibility in vitro. This study was divided into three treatments based on the level of NEO addition, which included 0 µL/L (T0), 100 µL/L (T1), and 200 µL/L (T2). The feed substrate composition consisted of king grass as forage and concentrate in a 60:40 ratio. Feed fermentation was conducted using the Menke and Steingass gas production and two-step Tilley and Terry in-vitro digestibility technique. The data obtained from the study were analyzed using one-way ANOVA and if there were differences between means, they were further assessed using DMRT. The results showed that T2 treatment significantly decreased (P < 0.05) ammonia (NH3) levels, total VFA, acetate, propionate, butyrate, and microbial protein (P < 0.05). Methane production and the activity of rumen protease enzyme significantly decreased (P < 0.05) at T1 and T2 treatment. The T2 treatment significantly reduced (P < 0.05) protein digestibility (IVCPD) at 48 h, while IVCPD at 96 h significantly increased (P < 0.05). On the other hand, the addition of nutmeg essential oil did not effect the activity of the amylase, carboxymethyl cellulase, and β-glucosidase enzymes, as well as the in-vitro digestibility of dry matter (IVDMD), crude fiber (IVCFD), and organic matter (IVOMD). The conclusion drawn from this study is that the optimum level for NEO is 200 µL/L, which can reduce methane production and increase crude protein digestibility at 96 h without any negative effect on rumen fermentation and nutrient digestibility.

Dietary Polysaccharide-Rich Extract from Noni (Morinda citrifolia L.) Fruit Modified Ruminal Fermentation, Ruminal Bacterial Community and Nutrient Digestion in Cashmere Goats

In two consecutive studies, we evaluated the effects of polysaccharide-rich noni (Morinda citrifolia L.) fruit extract (NFP) on ruminal fermentation, ruminal microbes and nutrient digestion in cashmere goats. In Exp. 1, the effects of a diet containing NFP of 0, 0.1%, 0.2%, 0.4% and 0.55% on in vitro ruminal fermentation at 3, 6, 9, 12 and 24 h were determined, whereas in Exp. 2, fourteen cashmere goats (46.65 ± 3.36 kg of BW ± SD) were randomly assigned to two treatments: the basal diet with or without (CON) supplementation of NFP at 4 g per kg DM (0.4%). The in vitro results showed that NFP linearly increased concentrations of volatile fatty acids (VFA), quadratically decreased ammonia-N concentration, and changed pH, protozoa number, gas production and the microbial protein (MCP) concentration, and was more effective at 0.4% addition, which yielded similar results in ruminal fermentation in Exp. 2. In addition, NFP increased the apparent digestibility of dry matter and crude protein and the abundance of Firmicutes, and reduced the abundance of Bacteroides and Actinobacteria. Ruminococcus_1 was positively associated with VFA concentration. The Rikenellaceae_RC9_gut_group was positively correlated with protozoa and negatively correlated with MCP concentration. Thus, NFP has potential as a ruminal fermentation enhancer for cashmere goats.

Bioprospecting essential oils of exotic species as potential mitigations of ruminant enteric methanogenesis

The inclusion of essential oils (EOs) in the diet of ruminants is one of the strategies used to alter ruminal microbial fermentation, improving feed efficiency, while simultaneously reducing enteric methane (CH4) production. This study aimed to evaluate the effects of three new EOs from plants exotic to the Azores, Pittosporum undulatum (PU), Hedychium gardnerianum (HG), and Cryptomeria japonica (CJ), on biogas production kinetics and in vitro CH4 production. Three levels of EOs (40, 80, and 120 μL/g dry matter (DM) were added to the basal diet to evaluate ruminal fermentation using the in vitro gas production technique. Added 800 mL of rumen inoculum with 5 g DM of the basal diet (BD) to all experimental units for 96 h, except for the blanks, to which only the inoculum was added. The total gas and CH4 produced by treatment incubation were recorded every hour after incubation until 96 h. The results showed that the gas production decreased significantly (P < 0.001) at 24 and 96 h after incubation, in the medium and high levels, with the essential oils PU, CJ, and HG treatment, when compared to the control treatment. The same significant differences (P < 0.001) were observed in in vitro CH4 production. The greatest reduction was noted with the addition of PUEO at the highest concentration (120 μL), which allowed a reduction in CH4 production at 24 h of 47% (P < 0.01). There was an interaction effect between EOs and concentration levels for all variables (P < 0.001). A decrease in total volatile fat acid (VFA) concentration (P < 0.05) was recorded compared to control, as well as the insoluble fraction and the potential degradation of the BD when EOs were included in the diet. In conclusion, the addition of EOs to the BD effectively reduced total enteric gas emissions and mitigated CH4 production. The most significant reduction of CH4 (47% in 24 h of incubation) occurs when 120 μL PUEO is added to each gram DM. The inclusion of OEs in the BD also affected the gas production kinetics and fermentation parameters.

A Comparison of Methods to Maintain the Equine Cecal Microbial Environment In Vitro Utilizing Cecal and Fecal Material

Simple Summary

In vitro systems for the fermentation of equine gastrointestinal (GI) content provide researchers with the ability to evaluate changes which may occur due to external influences but which cannot be accessed in vivo. The objective of this study was to evaluate three fermentation systems to replicate the equine cecal environment with regard to the microbiome and metabolite profile. The microbiome and metabolome of the fecal slurry used as inocula in this study were not representative of the cecal systems and care should be taken if feces are to be used to mimic proximal hindgut regions such as the cecum. However, the microbiome of the cecal inoculum maintained in either a chemostat batch fermenter or anaerobic chamber was fairly comparable. The metabolite concentrations, but not rate of production, were significantly different between the two cecal systems. These results provide a context to determine the most appropriate methods by which to create a fermentation system to reflect the equine cecal environment. They also highlight that caution must be exercised as many factors may influence the microbial and metabolic profiles within these systems; as such, they can best be used to demonstrate trends and gross reactions to environmental stimuli.

Abstract

The equine gastrointestinal (GI) microbiota is intimately related to the horse. The objective of the current study was to evaluate the microbiome and metabolome of cecal inoculum maintained in an anaerobic chamber or chemostat batch fermenter, as well as the fecal slurry maintained in an anaerobic chamber over 48 h. Cecal and fecal content were collected from healthy adult horses immediately upon death. Cecal fluid was used to inoculate chemostat vessels (chemostat cecal, n = 11) and vessels containing cecal fluid (anaerobic cecal, n = 15) or 5% fecal slurry (anaerobic fecal, n = 6) were maintained in an anaerobic chamber. Sampling for microbiome and metabolome analysis was performed at vessel establishment (0 h), and after 24 h and 48 h of fermentation. Illumina sequencing was performed, and metabolites were identified via nuclear magnetic resonance (NMR). Alpha and beta diversity indices, as well as individual metabolite concentrations and metabolite regression equations, were analyzed and compared between groups and over time. No differences were evident between alpha or beta diversity in cecal fluid maintained in either an anaerobic chamber or chemostat. The microbiome of the fecal inoculum maintained anaerobically shifted over 48 h and was not comparable to that of the cecal inoculum. Metabolite concentrations were consistently highest in chemostat vessels and lowest in anaerobic fecal vessels. Interestingly, the rate of metabolite change in anaerobic cecal and chemostat cecal vessels was comparable. In conclusion, maintaining an equine cecal inoculum in either an anaerobic chamber or chemostat vessel for 48 h is comparable in terms of the microbiome. However, the microbiome and metabolome of fecal material is not comparable with a cecal inoculum. Future research is required to better understand the factors that influence the level of microbial activity in vitro, particularly when microbiome data identify analogous communities.

Dose-response effects of the Savory (Satureja khuzistanica) essential oil and extract on rumen fermentation characteristics, microbial protein synthesis and methane production in vitro

The objective of the present study was to investigate dose-response effects of the essential oil (EO) and dry extract (EX) of Satureja khuzistanica (SK) on in vitro gas production kinetics, rumen fermentation, ruminal methanogenesis and microbial protein synthesis. So, EO and EX were tested at 0 (as control); 150 (low dose); 300, 450 (intermediate doses) and 600 mg/L (high dose). The gas produced over 24 h of incubation (GP24) decreased linearly with both EO and EX dosages (P<0.01). In vitro methane production was reduced by both EO (14–69%, depending on the included dose) and EX (7–58%). Microbial protein (MP) as well as the efficiency of microbial protein synthesis (EMPS) were improved by EO (18.8–49.8% and 20.4–61.5% for MP and EMPS, respectively) and to a lesser extent by EX (8.3–25.7% and 4.6–24.2% for MP and EMPS, respectively). Ammonia concentration was dropped in linear and quadratic manners with EO (P<0.05), and linearly with EX dosages (P<0.01). EO and EX exhibited depressive effects (in linear and quadratic (P<0.05), and linear manners (P<0.01), respectively) on total protozoa count. A mixed linear and quadratic effect was observed from both EO and EX on total VFA concentration (P<0.01). Total VFA concentration increased at 300 mg/L of EX, but decreased at high dose of both EO and EX. The acetate proportion increased with EO intermediate and high dosages, but it decreased at the expense of propionate at low and intermediate doses of EX. In total, these findings confirmed previous research on the great capacity of plant-based feed additives in positively modulating rumen fermentation that their effects may vary depending on the used doses. Specifically, these results suggest that EO and EX have high potentials to improve rumen functions at intermediate doses, which needs to be confirmed by in vivo experiments.

Effect of Tea Tree Oil on the Expression of Genes Involved in the Innate Immune System in Goat Rumen Epithelial Cells

Simple Summary

Subacute rumen acidosis (SARA) often causes significant losses on commercial farms. SARA is mainly caused by endotoxin (LPS) produced by the lysis of Gram-negative bacteria, which causes an inflammatory response. To alleviate the inflammatory response mediated by LPS, it is important to improve animal production performance. Tea tree oil (TTO) is a plant extract that possesses good bactericidal and anti-inflammatory effects. According to this study, LPS can significantly induce inflammatory responses in goat rumen epithelial cells (GRECs), while the addition of TTO could markedly mitigate inflammatory responses mediated by LPS in GRECs. Therefore, it may be useful for the treatment of SARA.

Abstract

In subacute rumen acidosis (SARA), the rumen epithelium is frequently attacked by endotoxin (LPS), which is caused by the lysis of dead Gram-negative bacteria. However, the rumen epithelium innate immune system can actively respond to the infection. Previous studies have demonstrated that tea tree oil (TTO) has good bactericidal and anti-inflammatory effects. Therefore, the aim of this study was to investigate the effect of TTO on the expression of genes involved in the inflammatory cytokines in goat rumen epithelial cells (GRECs) triggered by LPS. Our study shows that rumen epithelial cells isolated from goat rumen tissue can be cultured in vitro in 0.25% trypsin for a long time. These cells were identified as epithelial cells by the expression of cytokeratin 18, monocarboxylate transporter 4 (MCT4), Na[+]/H[+] hydrogen exchanger 1 (NHE1), putative anion transporter 1 (PAT1), vH⁺ ATPase B subunit (vH⁺ ATPase), and anion exchanger 2 (AE2). The mRNA expression of IL-1β, IL-6, TNF-α, TLR-2, NF-κB, CXCL6 and CXCL8 genes was significantly increased when LPS was used compared to untreated controls. In addition, mRNA expression of IL-1β, IL-6, TNF-α, TLR-2, NF-κB, CXCL8, CXCL6 and interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) genes was also significantly higher in the LPS group compared to the 0.05% TTO group. However, the expression of IL-1β, IL-6, TNF-α, TLR-2, CXCL6 and IFIT3 genes was significantly lower in the LPS and 0.05% TTO group compared to the 1 μg/mL LPS group. These results suggest that TTO can inhibit LPS-induced inflammatory cytokines expression in GRECs.

Evaluation of Terpenes' Degradation Rates by Rumen Fluid of Adapted and Non-adapted Animals

The aim of the present study was to evaluate terpenes degradation rate in the rumen fluid from adapted and non-adapted animals. Four castrated healthy animals, two rams and two bucks, were used. Animals were daily orally dosed for 2 weeks with 1 g of each of the following terpenes, α-pinene, limonene and β-caryophyllene. At the end of each week, rumen fluid (RF) samples were assayed in vitro for their potential to degrade terpenes over time. For each animal, a 10 mL reaction medium (RM) at a ratio 1:9 (v/v) was prepared and a terpenes solution at a concentration of 100 μg/ml each, was added in each RM tube. Tubes were incubated at 39 °C under anaerobic conditions and their contents sampled at 0, 2, 4, 8, 21 and 24 h. RF could degrade terpenes as it was shown by the significantly (P < 0.05) higher overall degradation rates. Individual terpene degradation rates, were significantly (P < 0.05) higher in week 5 for limonene and marginally (P = 0.083) higher also in week 5 for α-pinene. In conclusion, the findings of the present preliminary study suggest that terpenes can be degraded in the rumen fluid.

Effects of supplementation levels of Allium fistulosum L. extract on in vitro ruminal fermentation characteristics and methane emission

BACKGROUND

Ruminants release the majority of agricultural methane, an important greenhouse gas. Different feeds and additives are used to reduce emissions, but each has its drawbacks. This experiment was conducted to determine the effects of Allium fistulosum L. (A. fistulosum) extract on in vitro ruminal fermentation characteristics, and on methane emission.

METHODS

Rumen fluid was taken from two cannulated rumen Hanwoo cow (with mean initial body weight 450 ± 30 kg, standard deviation = 30). Rumen fluid and McDougall's buffer (1:2; 15 mL) were dispensed anaerobically into 50 mL serum bottles containing 300 mg (DM basis) of timothy substrate and A. fistulosum extracts (based on timothy substrate; 0%, 1%, 3%, 5%, 7%, or 9%). This experiment followed a completely randomized design performed in triplicate, using 126 individual serum bottles (six treatments × seven incubation times × three replicates).

RESULTS

Dry matter degradability was not significantly affected (p-value > 0.05) by any A. fistulosum treatment other than 1% extract at 24 h incubation. Methane emission linearly decreased A. fistulosum extract concentration increased at 12 and 24 h incubation (p-value < 0.0001; p-value = 0.0003, respectively). Acetate concentration linearly decreased (p-value = 0.003) as A. fistulosum extract concentration increased at 12 h incubation. Methanogenic archaea abundance tendency decreased (p-value = 0.055) in the 1%, 7%, and 9% A. fistulosum extract groups compared to that in the 0% group, and quadratically decreased (p-value < 0.0001) as A. fistulosum extract concentration increased at 24 h incubation.

CONCLUSION

A. fistulosum extract had no apparent effect on ruminal fermentation characteristics or dry matter degradability. However, it reduced methane emission and methanogenic archaea abundance.

Impact of a fumaric acid and palm oil additive on beef cattle performance and carcass characteristics in diets containing increasing concentrations of corn silage1

A feedlot study was conducted comparing a natural feed additive at varying corn silage (CS) inclusions on receiving and finishing cattle performance. The study utilized 480 crossbred steers (initial shrunk body weight [BW] = 296 kg; SD = 24.1 kg) in 48 pens with 10 steers/pen and 8 pens per treatment. Treatments were designed as a 2 × 3 factorial with 3 inclusions of CS (14%, 47%, 80%; dry matter [DM] basis) with or without (+, −) the inclusion of a feed additive containing fumaric acid and palm oil (FAPO). All treatment diets contained 16% modified distillers grains plus solubles and 4% supplement with dry-rolled corn replacing CS on a DM basis. All steers were fed the 80 CS diet and adapted to 47% and 14% CS over a 10- and 24-d period, respectively. Cattle fed 80 CS were fed for 238 days, 47 CS for 195 days, and 14% CS were fed for 168 days to a common backfat of 1.28 cm (P ≥ 0.59). There were no interactions for CS inclusion and the inclusion of FAPO on final body weight (FBW), DMI, ADG, G:F, hot carcass weight (HCW), LM area, marbling, or calculated yield grade (CYG; P ≥ 0.15). There was no significant difference for FBW, DMI, ADG, G:F, HCW, marbling, or CYG for cattle fed with or without FAPO (P ≥ 0.13). However, there was a quadratic response for FBW, ADG, G:F, HCW, marbling, and CYG with increased inclusion of CS (P ≤ 0.04). Inclusion of FAPO had no effect on performance. Feeding CS at greater inclusions decreased daily gain and feed efficiency but increased FBW when fed to an equal fat endpoint. CS gave greater returns ($/animal) when fed at 80% of diet DM. Feeding greater amounts of CS can be an economical way to finish cattle. In this study, FAPO did not affect animal performance, carcass characteristics, or economic return.

Exploring Additive, Synergistic or Antagonistic Effects of Natural Plant Extracts on In Vitro Beef Feedlot-Type Rumen Microbial Fermentation Conditions

Six Essential oils (EO) (tea tree oil-TeTr, oregano oil-Ore, clove bud oil-Clo, thyme oil-Thy, rosemary oil-Ros, and sage oil-Sag) in Experiment 1; and different combinations of selected oils in Experiment 2, were evaluate at four doses in an in vitro microbial fermentation system using ruminal fluid from beef cattle fed a 10:90 straw: Concentrate diet. In Experiment 1, TeTr, Ore, Clo and Thy improved rumen fermentation profile in a direction consistent with better feed utilization. In Experiment 2, TeTr mixed with Thy, Ore, Thy + Ore or Clo at 200 and 400 mg/L increased the molar proportion of propionate and decreased that of acetate, and the acetate to propionate ratio. However, the size of the effect was similar to that obtained with TeTr alone, suggesting that effects were not additive. When Thy, Ore or Thy + Ore where mixed with Clo, most effects on rumen fermentation profile disappeared, suggesting an antagonistic interaction of Clo with Thy and Ore. Results do not support the hypothesis of additivity among the EO tested, and antagonistic effects of Clo mixed with Thy or Ore were demonstrated at least in a low pH, beef-type fermentation conditions.

Effects of oregano essential oil on in vitro ruminal fermentation, methane production, and ruminal microbial community

Different inclusion rates of oregano essential oil (OEO) were investigated for their effects on ruminal in vitro fermentation parameters, total gas, methane production, and bacterial communities. Treatments were (1) control, 0 mg/L of OEO (CON); 13 mg/L (OEO1); 52 mg/L (OEO2); 91 mg/L (OEO3); and 130 mg/L (OEO4), each incubated with 150 mL of buffered rumen fluid and 1,200 mg of substrate for 24 h using the Ankom in vitro gas production system (Ankom Technology Corp., Fairport, NY). Treatment responses were statistically analyzed using polynomial contrasts. Digestibility of DM, NDF, and ADF increased quadratically with increasing OEO inclusion rates. Digestibility of DM and NDF were highest for OEO2, whereas ADF digestibility was highest for OEO3, compared with CON, with the remaining treatments being intermediate and similar. Ammonia nitrogen concentrations decreased from CON at a quadratic rate with increasing OEO inclusion rates, and OEO2 had the lowest concentration compared with the other groups. Total VFA, acetate, propionate, butyrate, valerate, and isovalerate concentrations linearly decreased with increasing OEO inclusion rates. Total gas production levels by CON and OEO4 were greater than those of OEO1, OEO2, and OEO3 in a quadratic response, and methane production linearly decreased from CON, compared with OEO4, at a decreasing rate with OEO inclusion rates. As determined by 16S rRNA sequencing, the α biodiversity of ruminal bacteria was similar among OEO inclusion rates. Increasing OEO inclusion rates linearly increased the relative abundance of Prevotella and Dialister bacteria. Several bacteria demonstrated different polynomial responses, whereas several bacteria were similar among increasing OEO inclusion rates. These results suggested that OEO supplementation can modify ruminal fermentation to alter VFA concentrations and reduce methane emissions by extensively altering the ruminal bacterial community, suggesting an optimal feeding rate for future animal studies of approximately 52 mg/L for mature ruminants.

Feeding oregano oil and its main component carvacrol does not affect ruminal fermentation, nutrient utilization, methane emissions, milk production, or milk fatty acid composition of dairy cows

Because of their antimicrobial properties, essential oils and their components have been suggested as alternatives to other antimicrobials (e.g., monensin) that are commonly fed to ruminants to improve nutrient utilization and enhance feed efficiency and milk performance. In this study, we evaluated the potential of oregano oil and its main component (carvacrol) as rumen modifiers. For this purpose, 8 ruminally cannulated lactating dairy cows (92 ± 11 d in milk, 36.5 ± 7.6 kg of milk yield, and 703 ± 74 kg of body weight) were used in a double 4 × 4 Latin square (28-d periods). Cows were fed 1 of the 4 following treatments: (1) control (CTL, no additive); (2) monensin [MON, 24 mg/kg of dry matter (DM)]; (3) oregano oil (ORE, 50 mg/kg of DM); and (4) carvacrol (CAR, 50 mg/kg of DM). Cows were fed (ad libitum intake) a total mixed ration consisting of 60% forages (corn silage and alfalfa silage) and 40% concentrates, on a DM basis. Feeding ORE and CAR had no effect on nutrient total-tract apparent digestibility, N utilization, rumen fermentation (i.e., pH, ammonia, volatile fatty acids), protozoa counts, or milk performance. Feeding MON increased the molar proportion of propionate and tended to increase total-tract apparent digestibility of crude protein. None of the feed additives evaluated affected enteric methane production (491 g/d, 21.1 g/kg of DM intake, 6.14% of gross energy intake on average). Milk fatty acid composition was not changed by ORE or CAR, but MON increased the proportion of trans-10 18:1, an intermediate of ruminal biohydrogenation. Thus, when included at 50 mg/kg of dietary dry matter, neither oregano oil nor carvacrol favorably altered rumen fermentation, improved nutrient utilization or milk performance, or mitigated enteric methane emissions in dairy cows.

Essential oils from Lippia turbinata and Tagetes minuta persistently reduce in vitro ruminal methane production in a continuous-culture system

The aim of the present study was to evaluate the impact of essential oils (EO) from Lippia turbinata (LT) and Tagetes minuta (TM) as well as the rotation of both EO on fermentation parameters in vitro. Daily addition of LT, TM, or a 3-day rotation between them (TM/LT), as well as a control (without EO), was evaluated using the rumen simulation technique (Rusitec). The experiment lasted 19 days, with a 7-day adaptation period, followed by 12 days of treatment (Days 0–12). The EO were dissolved in ethanol (70% vol/vol) to be added daily to fermenters (300 μL/L) from Day 0. Daily measurements included methane concentration, total gas production, apparent DM disappearance and pH, which started 2 days before the addition of treatments. On Days 0, 4, 8 and 12 apparent crude protein disappearance and neutral detergent fibre disappearance, ammonia and volatile fatty acid concentration and composition were determined. Methane production was significantly inhibited shortly after addition of both EO added individually, and persisted over time with no apparent adaptation to EO addition. The TM/LT treatment showed a similar effect on methane production, suggesting that rotating the EO did not bring further improvements in reduction or persistency compared with the inclusion of the EO individually. Gas production, total volatile fatty acid concentration and composition and apparent crude protein disappearance were not affected by EO addition. Compared with the control, a 5% reduction of apparent DM disappearance and a 15% reduction of neutral detergent fibre disappearance were observed with the addition of EO. Only TM and TM/LT reduced ammonia concentration. Given the significant and persistent antimethanogenic activity of both EO, and the potential of T. minuta to modify nitrogen metabolism, EO from these plant species are of interest for developing new feed additives with potential application in ruminant nutrition that are also likely to be acceptable to consumers.

Effects of eucalyptus oil and anise oil supplementation on rumen fermentation characteristics, methane emission, and digestibility in sheep

The objective of this study was to evaluate antimethanogenic activity of eucalyptus oil (EUC) and anise oil (ANI) in vitro and in vivo using sheep as a model. In vitro study was conducted using batch culture technique, each of EUC and ANI were added at 0, 50, 100, 200, or 400 mg/L of fermentation media with substrate containing 60% corn-based concentrate and 40% hay (DM basis). Total gas production (GP) linearly (P < 0.01) decreased with increasing ANI, whereas the GP was not affected with EUC addition. Supplementation of ANI and EUC linearly (P < 0.01) decreased total methane production and methane proportion in total gas. Total VFA and ammonia-nitrogen (NH3-N) concentration linearly (P < 0.01) decreased with increasing ANI supplementation. For the in vivo study, a replicated 3 × 3 Latin square design was carried out using six ruminal cannulated Du Han hybrid sheep (BW, 64.5 ± 8.56 kg) with 22 d of periods. Three treatments were control diet (consisted of 60% corn-based concentrate and 40% Chinese wildrye hay), EUC (control diet supplemented with 0.5 g EUC/d per head), and ANI (control diet supplemented with 0.5 g ANI/d per head). Each period consisted of 14 d for adaption and 8 d for sampling and data collection. Supplementation of EUC and ANI had no effects on feed intake and apparent nutrient digestibility. Ruminal NH3-N concentration was greater with EUC (P < 0.01) and ANI (P = 0.03) than control. Urinal allantoin output was less (P < 0.05) in sheep fed EUC and ANI than control animals. Methane emission was less (P = 0.03) in sheep fed ANI than sheep fed EUC, and a tendency of decrease for an eduction in this parameter was found for sheep fed with ANI (P = 0.08) compared to control. The in vitro results indicated a reduction of methane production with both EUC and ANI but in a dose-dependant manner. Supplementation of ANI tended to reduce ruminal methane production without adversely affecting rumen fermentation characteristics, nutrient intake, and digestibility, suggesting potential inhibition of ruminal methane emission in sheep supplemented with ANI.

In vitro Screening of Essential Oil Active Compounds for Manipulation of Rumen Fermentation and Methane Mitigation

The objective of this study was to investigate the effects of 11 active compounds of essential oils (ACEO) on rumen fermentation characteristics and methane production. Two trials were conducted. In trial 1, ACEO (eugenol, carvacrol, citral, limonene, 1,4-cineole, p-cymene, linalool, bornyl acetate, α-pinene, and β-pinene) at a dose of 1,000 μL/L were incubated for 24 h in diluted rumen fluid with a 70:30 forage:concentrate substrate (16.2% crude protein; 36.6% neutral detergent fiber). Three fistulated Holstein cows were used as donors of rumen fluid. The reduction in methane production was observed with nine ACEO (up to 86% reduction) compared with the control (p<0.05). Among these, only limonene, 1,4-cineole, bornyl acetate, and α-pinene did not inhibit volatile fatty acid (VFA) production, and only bornyl acetate produced less methane per mol of VFA compared with the control (p<0.05). In a subsequent trial, the effects on rumen fermentation and methane production of two concentrations (500 and 2,000 μL/L) of bornyl acetate, the most promising ACEO from the first trial, were evaluated using the same in vitro incubation method that was used in the first trial. In trial 2, monensin was used as a positive control. Both doses of bornyl acetate decreased (p<0.05) methane production and did not inhibit VFA production. Positive effects of bornyl acetate on methane and VFA production were more pronounced than the effects of monensin. These results confirm the ability of bornyl acetate to decrease methane production, which may help to improve the efficiency of energy use in the rumen.

Effects of essential oils from African basil on fermentation ofAndropogon gayanusgrass in the Artificial Rumen (RUSITEC)

Kouazounde, J. B., Gbenou, J. D., He, M., Jardim, T., Jin, L., Wang, Y., Beauchemin, K. A. and McAllister, T. A. 2015. Effects of essential oils from African basil on fermentation of Andropogon gayanus grass in the Artificial Rumen (RUSITEC). Can. J. Anim. Sci. 95: 425–431. Essential oils (EO) from African basil (Ocimum gratissimum) have shown the potential to modify rumen microbial fermentation and reduce ruminal methane production from grass forages in in vitro batch cultures. However, it is not known whether the effects of EO on rumen microbial fermentation attenuate over time. The objective of this study was to examine the effects of African basil EO at 0 (control), 100, 200 and 400 mg L−1incubation medium on microbial fermentation and methane production in the Rumen Simulation Technique (RUSITEC) using Andropogon gayanus grass as a substrate. African basil EO quadratically affected (P<0.05) methane production gas production and the pH of fermenter liquid. Total volatile fatty acid (VFA) production was linearly decreased (P<0.05) by African basil EO along with a shift in VFA profile towards less propionate and more acetate and butyrate. African basil EO quadratically altered (P<0.05) apparent dry matter, neutral detergent fiber digestibility,15N incorporation into total microbial protein and the total production of microbial protein. This study confirms that EO from African basil quadratically affected methane emissions arising from the ruminal fermentation of A. gayanus grass mainly by reducing overall digestibility of the forage.

Essential oils for dairy calves: effects on performance, scours, rumen fermentation and intestinal fauna

The first cause of death of dairy calves is often diarrhea which is mainly caused by pathogenic bacteria, which can result in excessive use of antibiotics. However, facing the increase concern by the industry and consumers, the use of antibiotics not only to control pathogens, but also to manipulate growth, has become a challenge. Alternative additives, such essential oils, have the potential to decrease antibiotic use, without reducing performance or increasing mortality of dairy calves. The objective of this study was to evaluate the use of a commercial blend of essential oils, incorporated into the calf starter and/or milk replacer to monitor the effect on overall calf performance, fecal scores and rumen fermentation parameters. A total of 30 Holstein calves received 6 l/day of a liquid diet, consisting of a commercial milk replacer containing 20% CP : 15% fat (EE). Calves had free choice access to water and calf starter. Weaning occurred at week 8, and calves were followed until the 10th week of age. Calves were assigned to one of the three treatment groups in a randomized block design.

TREATMENTS

(1) control without essential oils supplementation (C); (2) essential oils blend in the milk replacer at 400 mg/kg (MR) and (3) essential oils blend in the milk replacer (200 mg/kg) and starter feed (200 mg/kg) (MRS). From the 2nd week, calves were weighed and body measurements were taken, while concentrate intake and fecal scores were monitored daily. Blood samples were drawn weekly for determination of glucose and β-hydroxybutyrate. Fecal samples were collected weekly and analyzed for lactic acid bacteria and Enterobacteria; and ruminal fluid for determination of pH, short chain fatty acids, ammonia-N and counts of amylolytic and cellulolytic bacteria, and protozoa. Performance, fecal scores and intestines microorganisms were not affected by the essential oils supplementation. Ruminal and blood parameters were also not affected, with the exception the rumen ammonia-N concentration, with higher values when essential oils were supplemented in a combination of milk replacer and starter feed. Most of the evaluated parameters were affected by age of calves, mainly as a response to the increase in concentrate intake as animals' aged. Essential oils are promising substitutes for antibiotics. However, the dose and routes of administration deserve further studies, allowing a better animal performance and health to be achieved.

Short Communication: Assessment of lemongrass oil supplementation in a dairy diet on in vitro ruminal fermentation characteristics using the rumen simulation technique

Nanon, A., Suksombat, W., Beauchemin, K. A. and Yang, W. Z. 2014. Short Communication: Assessment of lemongrass oil supplementation in a dairy diet on in vitro ruminal fermentation characteristics using the rumen simulation technique. Can. J. Anim. Sci. 94: 731–736. A study using a rumen simulation technique (Rusitec) was conducted to investigate the effect of increasing lemongrass oil (LMO) supplementation on ruminal fermentation characteristics of a dairy cow diet. Increasing LMO from 0, to 100 to 200 mg kg−1 dry matter did not affect volatile fatty acid concentration, whereas LMO supplementation increased large and small peptide N and reduced ammonia N concentration. Adding 200 mg of LMO kg−1 dry matter also increased microbial N production. However, feed digestibility was not affected by LMO supplementation. These results suggest that the addition of LMO may inhibit deamination in the rumen.

Plant-derived antimicrobials reduce E. coli O157:H7 virulence factors critical for colonization in cattle gastrointestinal tract in vitro

This study investigated the effect of subinhibitory concentrations (SIC) of five plant-derived antimicrobials (PDAs), namely, trans cinnamaldehyde, eugenol, carvacrol, thymol, and β-resorcylic acid, on E. coli O157:H7 (EHEC) attachment and invasion of cultured bovine colonic (CO) and rectoanal junction (RAJ) epithelial cells. In addition, PDAs' effect on EHEC genes critical for colonization of cattle gastrointestinal tract (CGIT) was determined in bovine rumen fluid (RF) and intestinal contents (BICs). Primary bovine CO and RAJ epithelial cells were established and were separately inoculated with three EHEC strains with or without (control) SIC of each PDA. Following incubation, EHEC that attached and invaded the cells were determined. Furthermore, the expression of EHEC genes critical for colonization in cattle was investigated using real-time, quantitative polymerase chain reaction in RF and BICs. All the PDAs decreased EHEC invasion of CO and RAJ epithelial cells (P < 0.05). The PDAs also downregulated (P < 0.05) the expression of EHEC genes critical for colonization in CGIT. Results suggest that the PDAs could potentially be used to control EHEC colonization in cattle; however follow-up in vivo studies in cattle are warranted.

Lactobacillus plantarum IFPL935 impacts colonic metabolism in a simulator of the human gut microbiota during feeding with red wine polyphenols

The colonic microbiota plays an important role in the bioavailibility of dietary polyphenols. This work has evaluated the impact on the gut microbiota of long-term feeding with both a red wine polyphenolic extract and the flavan-3-ol metabolizer strain Lactobacillus plantarum IFPL935. The study was conducted in the dynamic Simulator of the Human Intestinal Microbial Ecosystem (SHIME). The feeding of the gut microbiota model with red wine polyphenols caused an initial decrease in the counts of total bacteria in the ascending colon (AC), with Bacteroides, Clostridium coccoides/Eubacterium rectale and Bifidobacterium being the most affected bacterial groups. The bacterial counts recovered to initial numbers faster than the overall microbial fermentation and proteolysis, which seemed to be longer affected by polyphenols. Addition of L. plantarum IFPL935 helped to promptly recover total counts, Lactobacillus and Enterobacteriaceae and led to an increase in lactic acid formation in the AC vessel at the start of the polyphenol treatment as well as butyric acid in the transverse (TC) and descending (DC) vessels after 5 days. Moreover, L. plantarum IFPL935 favoured the conversion in the DC vessel of monomeric flavan-3-ols and their intermediate metabolites into phenylpropionic acids and in particular 3-(3'-hydroxyphenyl)propionic acid. The results open the possibilities of using L. plantarum IFPL935 as a food ingredient for helping individuals showing a low polyphenol-fermenting metabotype to increase their colonic microbial capacities of metabolizing dietary polyphenols.

Influence of Albizia lebbeck Saponin and Its Fractions on In Vitro Gas Production Kinetics, Rumen Methanogenesis, and Rumen Fermentation Characteristics

The present study was undertaken to investigate the effect of crude seed powder (CSP) and gross saponins extract (GSE) of seeds of Albizia lebbeck on antimicrobial activity by taking two Gram-positive (Staphylococcus aureus and Bacillus cereus), two Gram-negative (Escherichia coli and Salmonella Typhi) bacteria, and two fungi species (Aspergillus niger and Candida butyric) were taken at 25, 50, 100, 250, and 500 µg levels using agar well diffusion method. Zone of inhibition was increased with increasing of concentration of CSP and saponins which indicates that Gram-negative bacteria (E. coli), Gram-positive bacteria (B. cereus), and A. niger were significantly susceptible to inhibition. Another experiment was conducted to study the effect of GSE and saponins fraction A and B of A. lebbeck supplementation at 6% on DM basis on methane production and other rumen fermentation parameters using in vitro gas production test, by taking three different type diets, that is, high fiber diet (D1, 60R : 40C), medium fiber diet (D2, 50R : 50C), and low fiber diet (D3, 40R : 60C). Significant (P ≤ 0.05) increase was seen in IVDMD, methane production; however ammonia nitrogen concentration decreased as compared to control. The methane production was reduced in a range between 12 and 49% by saponin supplemented diets except in case of GSE in D2. Sap A showed the highest methane reduction per 200 mg of truly digested substrate (TDS) than other treatment groups. Results in relation with quantification of methanogens and protozoa by qPCR indicated the decreasing trend with saponins of A. lebbek in comparison with control except total methanogen quantified using mcr-A based primer.

Eremophila glabra reduces methane production and methanogen populations when fermented in a Rusitec

Eremophila glabra Juss. (Scrophulariaceae), a native Australian shrub, has been demonstrated to have low methanogenic potential in a batch in vitro fermentation system. The present study aimed to test longer-term effects of E. glabra on rumen fermentation characteristics, particularly methane production and the methanogen population, when included as a component of a fermentation substrate in an in vitro continuous culture system (Rusitec). E. glabra was included at 150, 250, 400 g/kg DM (EG15, EG25, and EG40) with an oaten chaff and lupin-based substrate (control). Overall, the experiment lasted 33 days, with 12 days of acclimatization, followed by two periods during which fermentation characteristics (total gas, methane and VFA productions, dry matter disappearance, pH) were measured. The number of copies of genes specifically associated with total bacteria and cellulolytic bacteria (16S rRNA gene) and total ruminal methanogenic archaeal organisms (the methyl coenzyme M reductase A gene (mcrA)) was also measured during this time using quantitative real-time PCR. Total gas production, methane and volatile fatty acid concentrations were significantly reduced with addition of E. glabra. At the end of the experiment, the overall methane reduction was 32% and 45% for EG15 and EG25 respectively, compared to the control, and the reduction was in a dose-dependent manner. Total bacterial numbers did not change, but the total methanogen population decreased by up to 42.1% (EG40) when compared to the control substrate. The Fibrobacter succinogenes population was reduced at all levels of E. glabra, while Ruminococcus albus was reduced only by EG40. Our results indicate that replacing a portion of a fibrous substrate with E. glabra maintained a significant reduction in methane production and methanogen populations over three weeks in vitro, with some minor inhibition on overall fermentation at the lower inclusion levels.

Effects of plants and essential oils on ruminal in vitro batch culture methane production and fermentation

Tekippe, J. A., Hristov, A. N., Heyler, K. S., Zheljazkov, V. D., Ferreira, J. F. S., Cantrell, C. L. and Varga, G. A. 2012. Effects of plants and essential oils on ruminal in vitro batch culture methane production and fermentation. Can. J. Anim. Sci. 92: 395–408. In this study, plants (14) and essential oils (EO; 88) from plants that are naturalized to, or can be successfully grown in North America were evaluated in a batch culture in vitro screening experiments with ruminal fluid as potential anti-methanogenic additives for ruminant diets. Essential oils were tested at four inclusion levels: 0 (blank), 10, 50, and 100 mg L−1and plants were tested at 313, 1250, 2500, and 5000 mg L−1final incubation medium concentration. Compared with the blank, two of the EO increased acetate concentration (8 to 10%), 11 EO increased propionate concentration (9 to 23%), 10 EO increased butyrate concentration (24 to 29%), and three EO reduced methane production [20 to 30%; Anethum graveolens (dill weed oil), Lavandula latifolia, and Ocimum basilicum #7 accession]. Four EO decreased and one increased neutral detergent fiber (NDF) degradability. Three plants increased acetate concentration (8 to 12%), two increased propionate concentration (16%), and one (Origanum vulgare) decreased methane production (31%). Eight of the plants increased NDF degradability at various inclusion levels. Overall, these results indicate that some EO, or EO-producing plants could have a potential anti-methanogenic effect. Further research is needed to verify these results in vivo in long-term experiments.

Assessment of in vitro digestibility and fermentation parameters of alfalfa hay-based diet following direct incorporation of fenugreek seed (Trigonella foenum) and asparagus root (Asparagus officinalis)

This study was completed to evaluate the effect of fenugreek seed (Trigonella foenum; FS) and asparagus root (Asparagus officinalis; AR) on in vitro nutrient digestibility and fermentation patterns. Different levels [0%, 5%, 10%, 15% and 20% of dry matter (DM)] of the medicinal plants were included using alfalfa hay (AH) as a basal substrate at different incubation times (12, 18, 24 and 48 h). Total phenolic components of AH, FS and AR were 5.9, 10 and 8.3 g/kg DM, whereas total tannins were 0.4, 3.8 and 1.5 g/kg DM, respectively. Corresponding values for saponins were 10.4, 27.3 and 40.3 g/kg DM. Fenugreek seed increased (p<0.05) in vitro organic matter (OM) digestibility at different incubation times and decreased (p<0.05) crude protein (CP) digestibility at 18 and 24 h of incubation. Asparagus root also increased (p<0.05) in vitro OM digestibility and decreased (p<0.05) CP digestibility at different incubation times. Neutral detergent fibre digestibility was increased (p<0.05) by the addition of AR or FS at low levels, but decreased (p<0.05) noticeably by increasing level of two plants in the basal substrate. Ammonia-N concentration was markedly reduced (p<0.05) by the addition of AR at different incubation times, and this reduction was accompanied by the decrease in CP digestibility. True DM degradability and partitioning factor (ratio of substrate DM truly degraded to gas volume produced at different times of incubation) were increased, and total volatile fatty acid concentration and total gas production were decreased (p<0.05) with the addition of FS (at 10% and 15% DM levels) or AR (at 5%, 10% and 15% DM levels) at different incubation times. Results suggest that FS and AR may have potential as feed additives to increase the efficiency of nutrients' utilization, particularly of nitrogen in ruminant diets.

Effects of cinnamon leaf, oregano and sweet orange essential oils on fermentation and aerobic stability of barley silage

BACKGROUND

Silage additives are marketed with the primary aim of improving the fermentation and/or aerobic stability of silage. The objective of this study was to evaluate the impact of three different essential oils (EOs; cinnamon leaf (CIN), oregano (ORE) and sweet orange (SO)) on the fermentation characteristics and stability of barley silage. Chopped whole-plant barley (Hordem vulgare L.) forage was ensiled either untreated (0 mg kg⁻¹ dry matter (DM)) or treated with CIN, ORE or SO (37.5, 75 and 120 mg kg⁻¹ DM).

RESULTS

Moulds were not detected in any treatments, including the control, after 7 days of air exposure. All EOs at a concentration of 120 mg kg⁻¹ silage DM decreased (P = 0.001) yeast populations in comparison with the control during air exposure. Net gas, methane and ammonia concentrations in vitro did not differ among treatments. Changes in volatile fatty acid concentrations were small, and in situ data showed no changes in DM and neutral detergent fibre digestion rates for CIN, ORE or SO at concentrations up to 120 mg kg⁻¹ DM.

CONCLUSION

The findings from this study show that a concentration of 120 mg EO kg⁻¹ DM decreased yeast counts during aerobic stability tests. However, all EO treatments had minimal effects on data from in vitro and in situ incubations.

Rumen fermentation and production effects of Origanum vulgare L. leaves in lactating dairy cows

A lactating cow trial was conducted to study the effects of dietary addition of oregano leaf material (Origanum vulgare L.; OV; 0, control vs. 500 g/d) on ruminal fermentation, methane production, total tract digestibility, manure gas emissions, N metabolism, organoleptic characteristics of milk, and dairy cow performance. Eight primiparous and multiparous Holstein cows (6 of which were ruminally cannulated) were used in a crossover design trial with two 21-d periods. Cows were fed once daily. The OV material was top-dressed and mixed with a portion of the total mixed ration. Cows averaged 80 ± 12.5 d in milk at the beginning of the trial. Rumen pH, concentration of total and individual volatile fatty acids, microbial protein outflow, and microbial profiles were not affected by treatment. Ruminal ammonia-N concentration was increased by OV compared with the control (5.3 vs. 4.3mM). Rumen methane production, which was measured only within 8h after feeding, was decreased by OV. Intake of dry matter (average of 26.6 ± 0.83 kg/d) and apparent total tract digestibly of nutrients did not differ between treatments. Average milk yield, milk protein, lactose, and milk urea nitrogen concentrations were unaffected by treatment. Milk fat content was increased and 3.5% fat-corrected milk yield tended to be increased by OV, compared with the control (3.29 vs. 3.12% and 42.4 vs. 41.0 kg/d, respectively). Fat-corrected (3.5%) milk feed efficiency and milk net energy for lactation (NE(L)) efficiency (milk NE(L) ÷ NE(L) intake) were increased by OV compared with the control (1.64 vs. 1.54 kg/kg and 68.0 vs. 64.4%, respectively). Milk sensory parameters were not affected by treatment. Urinary and fecal N losses, and manure ammonia and methane emissions were unaffected by treatment. Under the current experimental conditions, supplementation of dairy cow diets with 500 g/d of OV increased milk fat concentration, feed and milk NE(L) efficiencies, and tended to increase 3.5% fat-corrected milk yield. The sizable decrease in rumen methane production with the OV supplementation occurred within 8h after feeding and has to be interpreted with caution due to the large within- and between-animal variability in methane emission estimates. The OV was introduced into the rumen as a pulse dose at the time of feeding, thus most likely having larger effect on methane production during the period when methane data were collected. It is unlikely that methane production will be affected to the same extent throughout the entire feeding cycle.

Synthetic and natural polyphenols with antioxidant properties stimulate rumen microbial growth in vitro

This trial compared the effects of two antioxidant phenols, butyl-hydroxyl-toluene (BHT) and a blend of polyphenols extracted from red chicory, on in vitro degradability, gas production (GP), volatile fatty acids, and microbial nitrogen production, using meadow hay and corn grain as fermentation substrates. A batch culture system with automated gas pressure detectors was used. Four replicates of each feed were incubated for 72 h without additive (Control, CTL) or with the addition of low (0.15 mg/g feed) or high (1.5 mg/g feed) dosages of BHT or red chicory. GP curves were fitted to estimate the time at which half of total GP (t1/2) was achieved. The t1/2 values for meadow hay and corn grain were ~16 and 9 h, respectively. A second incubation, conducted using the same experimental design, was stopped at t1/2. Compared with CTL, degradability and GP kinetics were not affected by the two dosages of BHT, except for GP, which increased after 48 h of incubation (P < 0.01). In the second incubation, BHT increased acetate at the expense of butyrate proportion (P < 0.01). Red chicory extract did not influence GP, feed degradability, or volatile fatty acids production in either incubation. Both BHT and red chicory induced a dosage-dependent increase in microbial nitrogen production at t1/2 (P < 0.05), on average from 7.0 to 13.9 mg/g DM. Collectively, our data suggest that increasing dosages of the two additives with antioxidant properties could have induced a shift in the partition of energy, with a higher proportion of nutrients channelled towards microbial protein synthesis.