Effects of long-term supplementation of chestnut and valonea extracts on methane release, digestibility and nitrogen excretion in sheep

The effect of Asparagopsis taxiformis, Ascophyllum nodosum, and Fucus vesiculosus on ruminal methanogenesis and metagenomic functional profiles in vitro

The ruminant-microorganism symbiosis is unique by providing high-quality food from fibrous materials but also contributes to the production of one of the most potent greenhouse gases-methane. Mitigating methanogenesis in ruminants has been a focus of interest in the past decades. One of the promising strategies to combat methane production is the use of feed supplements, such as seaweeds, that might mitigate methanogenesis via microbiome modulation and direct chemical inhibition. We conducted in vitro investigations of the effect of three seaweeds (Ascophyllum nodosum, Asparagopsis taxiformis, and Fucus vesiculosus) harvested at different locations (Iceland, Scotland, and Portugal) on methane production. We applied metataxonomics (16S rRNA gene amplicons) and metagenomics (shotgun) methods to uncover the interplay between the microbiome's taxonomical and functional states, methanogenesis rates, and seaweed supplementations. Methane concentration was reduced by A. nodosum and F. vesiculosus, both harvested in Scotland and A. taxiformis, with the greatest effect of the latter. A. taxiformis acted through the reduction of archaea-to-bacteria ratios but not eukaryotes-to-bacteria. Moreover, A. taxiformis application was accompanied by shifts in both taxonomic and functional profiles of the microbial communities, decreasing not only archaeal ratios but also abundances of methanogenesis-associated functions. Methanobrevibacter "SGMT" (M. smithii, M. gottschalkii, M. millerae or M. thaueri; high methane yield) to "RO" (M. ruminantium and M. olleyae; low methane yield) clades ratios were also decreased, indicating that A. taxiformis application favored Methanobrevibacter species that produce less methane. Most of the functions directly involved in methanogenesis were less abundant, while the abundances of the small subset of functions that participate in methane assimilation were increased.

IMPORTANCE

The application of A. taxiformis significantly reduced methane production in vitro. We showed that this reduction was linked to changes in microbial function profiles, the decline in the overall archaeal community counts, and shifts in ratios of Methanobrevibacter "SGMT" and "RO" clades. A. nodosum and F. vesiculosus, obtained from Scotland, also decreased methane concentration in the total gas, while the same seaweed species from Iceland did not.

Investigating the efficacy of purified tannin extracts from underutilized temperate forages in reducing enteric methane emissions in vitro

The study investigated how the concentration and composition of purified tannin extracts, at various inclusion rates, affect the ruminal in vitro fermentation parameters. Tannin extracts were isolated from four different forage species: birdsfoot trefoil (Lotus corniculatus), sulla (Hedysarum coronarium), big trefoil (Lotus pedunculatus), and salad burnet (Sanguisorba minor). Plants extracts were purified by Sephadex LH-20 gel chromatography and analyzed by UPLC-ESI-MS/MS. The results showed a large variation among the extracts from different species in terms of tannin composition and structural features. The extracts from salad burnet were dominated by hydrolysable tannins, comprising mainly ellagitannins. The extracts derived from sulla and big trefoil contained predominantly proanthocyanidins (PA), primarily composed of prodelphinidins with high mean degree of polymerisation (mDP). Birdsfoot trefoil extracts comprised procyanidin-rich PAs with low mDP. To determine whether the combined presence of tannins and flavonoid together lead to synergistic or antagonistic effects, the tannin extracts were incubated both with or without rutin at concentrations of 10, 20, and 30 g/kg DM, using a base substrate of perennial ryegrass (Lolium perenne, control). In general, all the tannin extracts decreased methane (CH4) production compared to the control, while no significant effect of rutin was observed on both gas (GP) and CH4 production, neither pure, nor in the simultaneous presence of tannins. The highest CH4 reduction (15%, at 30 g/kg DM) was observed from sulla and big trefoil extracts compared to control, but this was also supplemented with a concomitant reduction in GP (11%) indicating a reduction in feed digestibility. The extracts from birdsfoot trefoil and salad burnet reduced CH4 by up to 12% without significantly reducing GP, indicating the importance of tannin composition on ruminal fermentation.

Effects of Grape Pomace on Growth Performance, Nitrogen Metabolism, Antioxidants, and Microbial Diversity in Angus Bulls

Polyphenol-rich grape pomace (GP) represents a valuable processing by-product with considerable potential as sustainable livestock feed. This study aimed to investigate the effects of different levels of GP on the growth performance and nitrogen utilization efficiency, antioxidant activity, and rumen and rectum microbiota of Angus bulls. Thirty Angus bulls were allocated three dietary treatments according to a completely randomized design: 0% (G0), 10% (G10), and 20% (G20) corn silage dry matter replaced with dried GP dry matter. The results showed that the average daily gain (ADG) of the G0 group and G10 group was higher than that of the G20 group (p < 0.05); urinary nitrogen levels decreased linearly with the addition of GP (linear, p < 0.05). In terms of antioxidants, the levels of catalase (CAT) in the G10 group were higher than in the G0 and G20 groups (p < 0.05), and the total antioxidative capacity (T-AOC) was significantly higher than that in the G20 group (p < 0.05). In addition, in the analysis of a microbial network diagram, the G10 group had better microbial community complexity and stability. Overall, these findings offer valuable insights into the potential benefits of incorporating GP into the diet of ruminants.

Could natural phytochemicals be used to reduce nitrogen excretion and excreta-derived N2O emissions from ruminants?

Ruminants play a critical role in our food system by converting plant biomass that humans cannot or choose not to consume into edible high-quality food. However, ruminant excreta is a significant source of nitrous oxide (N2O), a potent greenhouse gas with a long-term global warming potential 298 times that of carbon dioxide. Natural phytochemicals or forages containing phytochemicals have shown the potential to improve the efficiency of nitrogen (N) utilization and decrease N2O emissions from the excreta of ruminants. Dietary inclusion of tannins can shift more of the excreted N to the feces, alter the urinary N composition and consequently reduce N2O emissions from excreta. Essential oils or saponins could inhibit rumen ammonia production and decrease urinary N excretion. In grazed pastures, large amounts of glucosinolates or aucubin can be introduced into pasture soils when animals consume plants rich in these compounds and then excrete them or their metabolites in the urine or feces. If inhibitory compounds are excreted in the urine, they would be directly applied to the urine patch to reduce nitrification and subsequent N2O emissions. The phytochemicals' role in sustainable ruminant production is undeniable, but much uncertainty remains. Inconsistency, transient effects, and adverse effects limit the effectiveness of these phytochemicals for reducing N losses. In this review, we will identify some current phytochemicals found in feed that have the potential to manipulate ruminant N excretion or mitigate N2O production and deliberate the challenges and opportunities associated with using phytochemicals or forages rich in phytochemicals as dietary strategies for reducing N excretion and excreta-derived N2O emissions.

Mitigation of ruminal methane production with enhancing the fermentation by supplementation of different tropical forage legumes

The aim of this research was to evaluate the influence of forage species adapted to the tropical region of Ecuador on gas production, enteric methane, digestion, and ruminal fermentation. The tree forage evaluated were C. arborea, E. fusca, B. forficata, E. poeppigiana, C. argentea, G. sepium, C. tora, and F. macrophylla. Ruminal fluid of four adult sheep fistulated with permanent cannulas in the rumen was used in the in vitro gas production technique. The in vitro gas production parameters were lower (P < 0.05) in the C. arborea (A = 41.68 mL gas/g DM, c = 0.044%/h and Lag = 1.654 h) and the average gas production rate for B. forficata was 1.017 mL/h (P < 0.05). C. arborea presented higher (P = 0.0001) effective degradation and real DM digestibility (40.461 g/kg and 82.51 mg/g, respectively). With respect to VFA, the highest (P < 0.05) proportion of acetic, propionic, and butyric was observed in C. arborea, G. sepium, and E. poeppigiana (72.52, 23.09, and 7.44 mol/100 mol, respectively) and the lowest (P = 0.0001) ratio: acetic/propionic was observed in G. sepium (2.92 mol/100 mol). The content of NH₃-N (mg/L) showed no difference. The lowest (P = 0.0001) methane production was observed in C. arborea (1.23 mL CH₄/g DM). The use of forage species of tropical climate rich in secondary metabolites in ruminant diets has the capacity to reduce the gas production and enteric methane; however, this is at the expense of the reduction of the fermentation of organic matter in the rumen.

The Utilisation of Tannin Extract as a Dietary Additive in Ruminant Nutrition: A Meta-Analysis

Simple Summary

Tannin has been extensively assessed for its potential and utilisation as a ruminant feed additive in recent years and is becoming important due to its beneficial effects on modulating ruminant performance and health and mitigating methane emissions. However, evidence concerning the effect of tannin in extracted forms on ruminants appears to be inconclusive on whether it can genuinely provide either beneficial or detrimental effects for ruminants. Moreover, the effects of various sources, types of tannin extract, or appropriate levels of supplementation on ruminants remain unclear. Therefore, there is a need for a systematic evaluation concerning the effects of tannin extract on rumen fermentation, digestibility, performance, methane emissions, and metabolism of ruminants.

Abstract

The objective of this meta-analysis was to elucidate whether there are general underlying effects of dietary tannin extract supplementation on rumen fermentation, digestibility, methane production, performance, as well as N utilisation in ruminants. A total of 70 papers comprised of 348 dietary treatments (from both in vivo and in situ studies) were included in the study. The database was then statistically analysed by the mixed model methodology, in which different experiments were considered as random effects and tannin-related factors were treated as fixed effects. The results revealed that an increased level of tannin extract inclusion in the diet lowered ruminant intake, digestibility, and production performance. Furthermore, the evidence also showed that an increased level of tannin extract decreased animal N utilisation where most of rumen by-pass protein was not absorbed well in the small intestine and directly excreted in the faeces. Due to the type of tannin extract, HT is more favourable to maintain nutrient intake, digestibility, and production performance and to mitigate methane production instead of CT, particularly when supplemented at low (<1%) to moderate (~3%) levels.

Pilot Study of the Effects of Polyphenols from Chestnut Involucre on Methane Production, Volatile Fatty Acids, and Ammonia Concentration during In Vitro Rumen Fermentation

Nutritional strategies can be employed to mitigate greenhouse emissions from ruminants. This article investigates the effects of polyphenols extracted from the involucres of Castanea mollissima Blume (PICB) on in vitro rumen fermentation. Three healthy Angus bulls (350 ± 50 kg), with permanent rumen fistula, were used as the donors of rumen fluids. A basic diet was supplemented with five doses of PICB (0%-0.5% dry matter (DM)), replicated thrice for each dose. Volatile fatty acids (VFAs), ammonia nitrogen concentration (NH3-N), and methane (CH4) yield were measured after 24 h of in vitro fermentation, and gas production was monitored for 96 h. The trial was carried out over three runs. The results showed that the addition of PICB significantly reduced NH3-N (p < 0.05) compared to control. The 0.1%-0.4% PICB significantly decreased acetic acid content (p < 0.05). Addition of 0.2% and 0.3% PICB significantly increased the propionic acid content (p < 0.05) and reduced the acetic acid/propionic acid ratio, CH4 content, and yield (p < 0.05). A highly significant quadratic response was shown, with increasing PICB levels for all the parameters abovementioned (p < 0.01). The increases in PICB concentration resulted in a highly significant linear and quadratic response by 96-h dynamic fermentation parameters (p < 0.01). Our results indicate that 0.2% PICB had the best effect on in-vitro rumen fermentation efficiency and reduced greenhouse gas production.

Effects of dietary grapeseed extract on performance, energy and nitrogen balance as well as methane and nitrogen losses of lambs and goat kids

The influence of phenol-rich dietary grapeseed extract on performance, energy and N balance and methane production was determined in sixteen lambs and thirteen goat kids (body weight 20·5 and 19·0 kg, 2 months of age, day 1 of study). Half of the animals received a concentrate containing grapeseed extract, and the others received concentrate without grapeseed extract (total extractable phenols analysed 27 v. 9 g/kg dietary DM; concentrate and hay 1:1). Diets were fed for 7 weeks with 1 week for determining intake, excretion and gaseous exchange in metabolism crates and respiration chambers. Overall, there was an adverse effect of the phenolic diet on apparent N digestibility and body N retention. Faecal N loss as proportion of N intake increased while urinary N loss declined. Relative to N intake, total N excretion was higher and body N retention lower in goat kids than lambs. Diets and animal species had no effect on methane emissions. The saliva of the goat kids had a higher binding capacity for condensed tannins (CT). Goat kids on the phenolic diet had higher CT concentrations in faeces and excreted more CT compared with the lambs (interaction species × diet P < 0·001). The lambs had overall higher (P < 0·001) urinary phenol concentrations than the goat kids (2·19 v. 1·48 g/l). The negative effect on body N retention and lack of effect on methane emissions make the use of the extract in the dosage applied not appealing. Species differences need to be considered in future studies.

Nitrous oxide emissions from the urine of beef cattle as regulated by dietary crude protein and gallic acid1

Two consecutive trials were carried out to study the effects of dietary CP and adding gallic acid (GA) in basal rations on nitrogen (N) metabolism and nitrous oxide (N2O) emissions from the urine of beef cattle. In Trial I, eight Simmental castrated male cattle with initial liveweight of 310.5 ± 21.5 kg were used as experimental animals. Two levels of dietary CP (113.5 and 150.8 g/kg DM) and two levels of GA (0.0 and 15.2 g/kg DM) were used as experimental treatments in a 2 × 2 reversal design. Two cattle received each treatment in each of two experimental periods. Each experimental period lasted 19 d, of which the first 14 d were for adaptation and the last 5 d were for sampling. In Trial II, the urine samples collected from Trial I were used for measuring N2O-N emissions using static incubation technique. Glass jars containing soil were used as the incubation vessels. Three jars were used for each of the urine samples as replicates and two jars without urine samples were used as blanks. The incubation lasted 15 d, and the daily N2O-N emission from each jar was determined using gas chromatography. The results showed that no effects of interactions were found between dietary CP and GA on the N metabolism of beef cattle and the estimated cattle N2O-N emissions (P > 0.05). Increasing dietary CP from 113.5 to 150.8 g/kg DM increased the excretions of total N, urinary N, and urea (P < 0.001), whereas adding GA at 15.2 g/kg DM in ration did not affect these parameters (P > 0.05). Increasing dietary CP from 113.5 to 150.8 g/kg DM increased the estimated cattle urine N2O-N emissions by 36.8% (without adding GA) and 32.3% (adding GA at 15.2 g/kg DM) (P < 0.01), whereas adding GA at 15.2 g/kg DM in ration decreased the estimated cattle urine N2O-N emissions by 28.5% (dietary CP 113.5 g/kg DM) and 30.9% (dietary CP 150.8 g/kg DM) (P < 0.01). The inhibiting effects of GA on decreasing the N2O-N emissions of urine could have been resulted from the effects of GA metabolites including pyrogallol and resorcinol excreted in urine. Feeding cattle with relatively low dietary CP or adding GA in ration is effective to decrease the N2O-N emissions from the urine patches of beef cattle applied to soil.

Use of gallic acid and hydrolyzable tannins to reduce methane emission and nitrogen excretion in beef cattle fed a diet containing alfalfa silage1,2

The objective of this study was to determine the effects of different forms of hydrolyzable tannin [HT; source (chestnut, CN; tannic acid, TA); subunit (gallic acid, GA)] on apparent total-tract digestibility, methane (CH4) production, and nitrogen (N) utilization in beef cattle fed an alfalfa silage-based diet. Eight ruminally cannulated heifers with an initial BW of 480 ± 29.2 kg (mean ± SD) were used in a double 4 × 4 Latin square experiment. The experiment consisted of four 28-d periods (14-d adaptation, 14-d measurements) and a 7-d washout between periods. The animals received a basal diet with 19.8% CP (DM basis) content containing 75% alfalfa silage, 20% barley silage, and 5% supplement (DM basis) with or without different forms of HT. The dietary treatments were as follows: control (no HT), GA (1.5% of diet DM), TA (1.5% of diet DM), and CN (2% of diet DM). Animals were fed 95% of their ad libitum intake during the measurement phase. Total fecal excretion was collected for 4 d, CH4 was measured for 72 h using respiration chambers, and ruminal fermentation variables and plasma urea N (PUN) concentration were measured on 2 nonconsecutive days before and after feeding. The restricted DM (DMI; 10.79 ± 1.076 kg/d) and nutrient intakes did not differ (P ≥ 0.22) among treatments. Furthermore, apparent DM digestibility (60.3 ± 0.86%) was not affected (P = 0.20) by treatment, but CP digestibility decreased for TA and CN compared with control and GA treatments (63.1 vs. 69.0%; P < 0.001). Total VFA concentration tended (P = 0.089) to increase for GA compared with control and TA (134 vs. 125 and 126 mM) and intermediate for CN (129 mM). The PUN concentration was lower for all HT treatments compared with control (196 vs. 213 mg/L; P = 0.02). Both TA and CN increased the proportion of N excreted in feces and decreased the proportion in urine compared with control and GA (43.9% vs. 37.8% and 56.1% vs. 62.2%; respectively; P < 0.001). However, the proportion of urea N in urinary N decreased for all HT treatments compared with control (47.2% vs. 51.2%; P = 0.02). Also, GA tended to decrease CH4/DMI (20.4 vs. 22.3 g/kg DMI; P = 0.07) and decreased the proportion of GE intake emitted as CH4 (5.16 vs. 5.71%; P = 0.04) compared with control. Thus, among the different forms of HT applied to a high-protein alfalfa silage-based diet, both TA and CN had no effect on CH4 production, but decreased CP digestibility and shifted N excretion from urine to feces, whereas GA (i.e., HT subunit) decreased CH4 production and decreased the proportion of urea N in urinary N in beef cattle without affecting CP digestibility. Thus, feeding the HT subunit, GA, has the potential to decrease environment impact of ruminants (lower CH4 and ammonia emissions), without decreasing animal performance.

Phenolic plant extracts are additive in their effects against in vitro ruminal methane and ammonia formation

Objective

The methane mitigating potential of various plant-based polyphenol sources is known, but effects of combinations have rarely been tested. The aim of the present study was to determine whether binary and 3-way combinations of such phenol sources affect ruminal fermentation less, similar or more intensively than separate applications.

Methods

The extracts used were from Acacia mearnsii bark (acacia), Vitis vinifera (grape) seed, Camellia sinensis leaves (green tea), Uncaria gambir leaves (gambier), Vaccinium macrocarpon berries (cranberry), Fagopyrum esculentum seed (buckwheat), and Ginkgo biloba leaves (ginkgo). All extracts were tested using the Hohenheim gas test. This was done alone at 5% of dry matter (DM). Acacia was also combined with all other single extracts at 5% of DM each, and with two other phenol sources (all possible combinations) at 2.5%+2.5% of DM.

Results

Methane formation was reduced by 7% to 9% by acacia, grape seed and green tea and, in addition, by most extract combinations with acacia. Grape seed and green tea alone and in combination with acacia also reduced methane proportion of total gas to the same degree. The extracts of buckwheat and gingko were poor in phenols and promoted ruminal fermentation. All treatments except green tea alone lowered ammonia concentration by up to 23%, and the binary combinations were more effective as acacia alone. With three extracts, linear effects were found with total gas and methane formation, while with ammonia and other traits linear effects were rare.

Conclusion

The study identified methane and ammonia mitigating potential of various phenolic plant extracts and showed a number of additive and some non-linear effects of combinations of extracts. Further studies, especially in live animals, should concentrate on combinations of extracts from grape seed, green tea leaves Land acacia bark and determine the ideal dosages of such combinations for the purpose of methane mitigation.

Energy utilization, nitrogen balance and microbial protein supply in cattle fed Pennisetum purpureum and condensed tannins

The aim of the experiment was to assess the effect of condensed tannins (CT) on feed intake, dry matter digestibility, nitrogen balance, supply of microbial protein to the small intestine and energy utilization in cattle fed a basal ration of Pennisetum purpureum grass. Five heifers (Bos taurus × Bos indicus) with an average live weight of 295 ± 19 kg were allotted to five treatments consisting of increasing levels of CT (0, 1, 2, 3 and 4% CT/kg DM) in a 5 × 5 Latin square design. Dry matter intake (DMI) was similar (p > 0.05) between treatments containing 0, 1, 2 and 3% of CT/kg DM and it was reduced (p < 0.05) to 4% CT (5.71 kg DM/day) with respect to that observed with 0% CT (6.65 kg DM/day). Nitrogen balance, purine derivatives excretion in urine, microbial protein synthesis and efficiency of synthesis of microbial nitrogen in the rumen were not affected (p ≥ 0.05) by the increase in the levels of condensed tannins in the ration. Energy loss as CH₄ was on average 2.7% of the gross energy consumed daily. Metabolizable energy intake was 49.06 MJ/day in cattle fed low-quality tropical grass with a DMI of 6.27 kg/day. It is concluded that concentrations of CT between 2 and 3% of DM of ration reduced energy loss as CH₄ by 31.3% and 47.6%, respectively, without affecting intakes of dry and organic matter; however, digestibilities of dry and organic matter are negatively affected.

Development of methodology for identification the nature of the polyphenolic extracts by FTIR associated with multivariate analysis

Tannins are polyphenolic compounds of complex structures formed by secondary metabolism in several plants. These polyphenolic compounds have different applications, such as drugs, anti-corrosion agents, flocculants, and tanning agents. This study analyses six different type of polyphenolic extracts by Fourier transform infrared spectroscopy (FTIR) combined with multivariate analysis. Through both principal component analysis (PCA) and hierarchical cluster analysis (HCA), we observed well-defined separation between condensed (quebracho and black wattle) and hydrolysable (valonea, chestnut, myrobalan, and tara) tannins. For hydrolysable tannins, it was also possible to observe the formation of two different subgroups between samples of chestnut and valonea and between samples of tara and myrobalan. Among all samples analysed, the chestnut and valonea showed the greatest similarity, indicating that these extracts contain equivalent chemical compositions and structure and, therefore, similar properties.