Methane emissions by goats consuming Sericea lespedeza at different feeding frequencies

Characterization of the ruminal microbiota in sheep and goats fed different levels of tannin-rich Sericea lespedeza hay

Understanding ruminal microbiota and diet-host breed interactions under forage feeding conditions is essential for optimizing rumen fermentation and improving feed efficiency in small ruminants. This study aimed to investigate the effects of different ratios of condensed tannin-rich Sericea lespedeza (SL; Lespedeza cuneata) in the diets on changes and interactions of ruminal microbiota and host species (i.e., sheep and goats). Katahdin sheep (n = 12) and Alpine goats (n = 12) at approximately 10 to 12 mo of age were blocked by body weight (BW = 30.3 and 25.5 kg, respectively) and randomly assigned to one of the 3 treatments. Diets contained 75% coarsely ground forage and 25% concentrate. The forages were 1) 100% alfalfa hay (AL), 2) 100% SL, and 3) 50% AL + 50% SL (ASL). In the present study, the diversity and composition of ruminal microbiota differed between sheep and goats fed similar diets. Based on the taxonomic analysis, there was a distinct clustering pattern (P < 0.05) for sheep by diets, but such a pattern was not observed for goats (P > 0.1). The most predominant phyla were Firmicutes, Bacteroidetes, Ascomycota, and methanogen species of Methanobrevibactor sp. in the rumen of sheep and goats, regardless of diets. The Bacteroidetes and Ascomycota were enriched in sheep fed AL and ASL. In contrast, these microbial phyla were enhanced in goats fed tannin-rich SL diets, with the diet-by-host species interaction (P < 0.02) for the Bacteroidetes phylum. Sheep rumen fluid samples showed a higher degree of variability in microbial community composition compared to goat rumen fluid samples. The relative proportion of the Aspergillus fungi population was reduced to 90.7% in the SL group compared with the AL group, regardless of host species. The antimicrobial activity of tannins and greater sensitivities of selected microbiota species to these tannin compounds during SL feeding in sheep and goats perhaps caused this difference. The results from this study suggest that differences in the microbiota were associated with differences in diets and host species. Therefore, this study provides a better understanding of ruminal microbiota and diet-host species interactions under various tannin-rich diets, which could advance consolidative information on rumen microbiome community diversity changes and may improve sheep and goat production.

Anthelmintic activity of Carica pubescens aqueous seed extract and its effects on rumen fermentation and methane reduction in Indonesian thin-tailed sheep: An in vitro study

Background and Aim

Seeds from Carica pubescens were observed to be abundant as waste. This waste contains active plant compounds whose utilization has not been studied in the livestock sector. This study was conducted to evaluate the potential of an aqueous seed extract of Carica pubescens (ASE) as an anthelmintic agent during rumen fermentation and methane reduction.

Materials and Methods

Aqueous seed extract of Carica pubescens was prepared from C. pubescens cultivated in Wonosobo, Indonesia. Phytochemical analyses were performed to quantify the secondary metabolite content of ASE. In vitro adult worm mortality tests, scanning electron microscopy, and gas production tests were conducted to evaluate rumen characteristics, methane reduction, and the potential of ASE as an anthelmintic against Haemonchus contortus. Adult worms and ruminal fluid were collected from Indonesian thin-tailed sheep. Two-way analysis of variance followed by Tukey's test was performed using the Statistical Package for the Social Sciences® 21.0 software to detect significant differences.

Results

In vitro study results showed that 1-5% ASE inhibited H. contortus after the 1st h of incubation, and 5% ASE suppressed 100% of adult H. contortus worms in the 5th h. Scanning electron microscopy analysis of ASE-treated worms ASE revealed damaged cuticle structures. ASE had no significant effect on pH, NH3, volatile fatty acid, acetate, propionate, butyrate, acetate: propionate, or microbial protein in rumen fluid (p > 0.05). The in vitro feed fermentation results showed that ASE significantly affected methane reduction.

Conclusion

The inclusion of up to 5% ASE in sheep diets may serve as a potential alternative anthelmintic against H. contortus as well as a methane reduction agent, without deleterious effects on rumen fermentation.

Roles of Essential Oils, Polyphenols, and Saponins of Medicinal Plants as Natural Additives and Anthelmintics in Ruminant Diets: A Systematic Review

Public awareness on health and safety issues in using antibiotics for livestock production has led many countries to ban the use of all growth-promoting antibiotics (GPA) for livestock feeding. The ban on the utilization of antibiotics in livestock, on the other hand, is an opportunity for researchers and livestock practitioners to develop alternative feed additives that are safe for both livestock and the consumers of animal derived foods. Many feed additives were developed from a number of plants that contain secondary metabolites, such as essential oils, polyphenols, and saponins. These secondary metabolites are extracted from various parts of many types of plants for their uses as feed additives and anthelmintics. Recent investigations on using essential oils, polyphenols, and saponins as dietary additives and anthelmintics demonstrate that they can increase not only the production and health of ruminants but also ensure the safety of the resulting foods. There are many publications on the advantageous impacts of dietary plant bioactive components on ruminants; however, a comprehensive review on individual bioactive constituents of each plant secondary metabolites along with their beneficial effects as feed additives and anthelmintics on ruminants is highly required. This current study reviewed the individual bioactive components of different plant secondary metabolites and their functions as additives and anthelmintics to improve ruminant production and health, with respect to safety, affordability and efficiency, using a systematic review procedure.

Differences between Yaks and Qaidam Cattle in Digestibilities of Nutrients and Ruminal Concentration of Volatile Fatty Acids Are not Dependent on Feed Level

The Qinghai–Tibetan Plateau (QTP) is characterized by highly fluctuating seasonal pastures. Yaks (Bos grunniens) graze at higher altitudes than Qaidam cattle (Bos taurus), but the two bovine species co-graze in their overlapping ranges. We hypothesized that yaks would digest nutrients to a greater extent and utilize energy more efficiently than cattle at low dietary intakes, but the difference between bovine species would not be apparent at high intakes. To test this hypothesis, six yaks (203 ± 6.0 kg) and six Qaidam cattle (214 ± 9.0 kg), all 3.5-year-old castrated males, were used in two concurrent 4 × 4 Latin square designs with two extra steers of each species in each period. The digestibilities of dry matter, organic matter, crude protein, ether extract, neutral and acid detergent fiber were greater (p < 0.05) in yaks than in cattle and decreased linearly (p < 0.05) when feed level (FL) increased. The average daily gain (ADG), the ratios of digestible energy (DE) to gross energy and metabolizable energy (ME) to DE, and ruminal total volatile fatty acids and ammonia-N concentrations were greater (p < 0.001) in yaks than in cattle and increased linearly (p < 0.001) when FL increased. Based on the regression equations of ADG on ME intake, the daily ME requirement for maintenance in yaks was 0.53 MJ BW−0.75 d−1, which was lesser (p < 0.05) than the 0.62 MJ BW−0.75 d−1 in cattle. We concluded that: (1) when differences between breeds emerged, the differences existed for all FLs; (2) maintenance energy requirement was lesser and ADG was greater in yaks than in cattle; (3) the digestibilities of nutrients were greater in yaks than in cattle when consuming only oat hay pellets. These findings indicate that yaks adapt to fluctuating dietary intakes in harsh environments by having a low energy requirement and high digestibility of nutrients, independent of the FL.

Effects of Dietary Inclusion of Sericea Lespedeza Hay on Feed Intake, Digestion, Nutrient Utilization, Growth Performance, and Ruminal Fermentation and Methane Emission of Alpine Doelings and Katahdin Ewe Lambs

Twenty-four Alpine doelings, initial 25.3 ± 0.55 kg body weight (BW) and 10.4 ± 0.11 mo of age, and 24 Katahdin ewe lambs, 28.3 ± 1.02 kg BW and 9.6 ± 0.04 mo of age, were used to determine effects of dietary inclusion of Sericea lespedeza (Lespedeza cuneata) hay on feed intake, digestion, growth performance, energy metabolism, and ruminal fermentation and methane emission. There were four periods, the first three 42 days in length and the fourth 47 days. Diets consumed ad libitum contained 75% coarsely ground hay with alfalfa (ALF), a 1:1 mixture of ALF and LES (ALF+LES), and LES (10.0% condensed tannins; CT). The intake of dry matter (DM) tended to be greater (p = 0.063) for Katahdin than for Alpine (4.14 vs. 3.84% BW; SEM = 0.110). The dry matter intake was similar among the diets (3.97, 4.10, and 3.89% BW for ALF, ALF+LES, and LES, respectively; SEM = 0.134). The digestion of organic matter (75.3, 69.3, and 65.5%; SEM = 0.86), neutral detergent fiber (61.7, 50.5, and 41.4%; SEM = 1.49), and nitrogen (78.8, 66.9, and 50.8% for ALF, ALF+LES, and LES, respectively; SEM = 0.92) decreased as the dietary concentration of lespedeza increased (p < 0.05). However, there was an interaction (p < 0.05) between the breed and diet in nitrogen digestion, with a greater value for goats vs. sheep with LES (54.4 vs. 47.3%; SEM = 1.30). The digested nitrogen intake decreased markedly with the increasing quantity of lespedeza (38.0, 27.5, and 15.7 g/day for ALF, ALF+LES, and LES, respectively; SEM = 1.26). The average daily gain was greater for Katahdin than for Alpine (p < 0.001; 180 vs. 88 g, SEM = 5.0) and ranked (p < 0.05) ALF > ALF+LES > LES (159, 132, and 111 g, respectively; SEM = 6.1). The ruminal methane emission differed (p < 0.05) between animal types in MJ/day (1.17 and 1.44), kJ/g DM intake (1.39 and 1.23), and kJ/g ADG (18.1 and 9.8 for Alpine and Katahdin, respectively). Regardless of the period and animal type, diet did not impact methane emission in MJ/day or relative to DM intake, BW, or ADG (p > 0.05). The digestible and metabolizable energy intakes, heat production, and retained energy were not affected by diet (p > 0.05). In conclusion, future research should consider the marked potential effect of CT of forages such as lespedeza on nitrogen digestion and associated effects on protein status and other conditions that may be impacted.

Evaluation of in vitro energy distribution and methanogenic potential of two forages with the addition of condensed tannins

The objective of this work was to analyze the effect of the addition of condensed tannins (CT) in the efficiency of digestion, methanogenic potential and energy distribution between the fermentation products of two forages. An assay was carried out using the in vitro gas production technique in which extracts of Quebracho (Schinopsis balansae) and Lotus corniculatus were evaluated with fermentation patterns of derived products from Ryegrass (RG, Lolium perenne) and a tropical forage, Megathyrsus maximus (MM). Tannins were added to the substrate at a concentration of 30 mg g-1. MM presented higher and delayed gas production (GP), and in vitro dry matter, organic matter and fiber digestibilities (ivDMD, ivOMD and NDFD, respectively) were relatively high but lower than RG. In addition, MM presented higher CH4 production (CH4p) than RG in 24 and 48h. Even though CT of Quebracho induced a decrease in the NDFD, contrary to what was expected, CH4p was greater, although this effect could not be attributed to the presence of CT. The stoichiometric evaluation indicated that while the highest CH4p in Quebracho treatments were associated with acetogenic profiles, CH4p with Lotus did not show any relationship with the volatile fatty acids (VFA) profile, but it did show a relationship with the highest total VFA production and the highest GP.

Effect of tannins from tropical plants on methane production from ruminants: A systematic review

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A negative relationship was observed between the level of tannin inclusion and CH₄ emission.

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The effect of CH₄ mitigation is increasing as the level of tannin inclusion is higher.

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Sub-group analysis revealed differences of tannins supplementation response according to CH₄ emission measurements techniques.

Methane (CH₄) is a greenhouse gas generated during the feed fermentation processes in the rumen. However, numerous studies have been conducted to determine the capacity of plant secondary metabolites to enhance ruminal fermentation and decrease CH₄ production, especially those plants rich in tannins. This review conducted a descriptive analysis and meta-analysis of the use of tannin-rich plants in tropical regions to mitigate CH₄ production from livestock. The aim of this study was to analyse the effect of tannins supplementation in tropical plants on CH₄ production in ruminants using a meta-analytic approach and the effect on microbial population. Sources of heterogeneity were explored using a meta-regression analysis. Final database was integrated by a total of 14 trials. The ‘meta’ package in R statistical software was used to conduct the meta-analyses. The covariates defined a priori in the current meta-regression were inclusion level, species (sheep, beef cattle, dairy cattle, and cross-bred heifers) and plant. Results showed that supplementation with tropical plants with tannin contents have the greatest effects on CH₄ mitigation . A negative relationship was observed between the level of inclusion and CH₄ emission (−0.09), which means that the effect of CH₄ mitigation is increasing as the level of tannin inclusion is higher. Therefore, less CH₄ production will be obtained when supplementing tropical plants in the diet with a high dose of tannins.

Dietary mitigation of enteric methane emissions from ruminants: A review of plant tannin mitigation options

Methane gas from livestock production activities is a significant source of greenhouse gas (GHG) emissions which have been shown to influence climate change. New technologies offer a potential to manipulate the rumen biome through genetic selection reducing CH4 production. Methane production may also be mitigated to varying degrees by various dietary intervention strategies. Strategies to reduce GHG emissions need to be developed which increase ruminant production efficiency whereas reducing production of CH4 from cattle, sheep, and goats. Methane emissions may be efficiently mitigated by manipulation of natural ruminal microbiota with various dietary interventions and animal production efficiency improved. Although some CH4 abatement strategies have shown efficacy in vivo, more research is required to make any of these approaches pertinent to modern animal production systems. The objective of this review is to explain how anti-methanogenic compounds (e.g., plant tannins) affect ruminal microbiota, reduce CH4 emission, and the effects on host responses. Thus, this review provides information relevant to understanding the impact of tannins on methanogenesis, which may provide a cost-effective means to reduce enteric CH4 production and the influence of ruminant animals on global GHG emissions.

Productive behavior in growing kid goats and methane production with the inclusion of chokecherry leaf (Prunus salicifolia)

Currently for the reduction of methane (CH4) emissions are using fodder rich in condensed tannins, however, not yet known exactly how they act in the rumen is not yet clear. The objective of this study was to evaluate the effect of the inclusion of leaves of Prunus salicifolia (PS, 0%, 15%, and 30%) on the productive behavior of growing kid goats, methane production, nutritional value, fermentation, and ruminal digestibility through an in vivo and in vitro study was performed. Diets were administered ad libitum to 6 Saanen kids with live weight (LW) of 12.25 ± 2.25 kg. Three levels of inclusion were used in a diet based on ground corn grain, soybean meal, corn stover, and oat hay in substitution with P. salicifolia leaves. The in vivo productive behavior was determined, as well as the fermentation kinetics, in vitro gas production, CH4 and hydrogen (H2) in an in vitro system was determined. For the in vivo study, we used a 3 × 3 Latin square design in in vivo study and an analysis of variance with three replications for in vitro gas production. The inclusion of 30% increased (P = 0.0011) dry matter intake (DMI 589.33 g/day) compared to the control group (418.80 g/day). The highest N excretion (feces and urine) (P < 0.001) was for T0, in addition to presenting a negative nitrogen balance compared with T15 and T30. The production of CH4 (mM)/g DM incubated, and CH4 (mM)/g DM fermented, CH4 (mM/day), and H2 was lower (P < 0.05) in T30 than T0 and T15. CH4 (mM)/day was lower (P < 0.036) in T130 (283 mM/day) compared with T0 (407 mM/day) P. salicifolia is a forage that helps to reduce the production of methane and can be included in the diets of growing kid goats in amounts less than 30% without affecting production performance.

Ericaceous species reduce methane emissions in sheep and red deer: Respiration chamber measurements and predictions at the scale of European heathlands

Despite the importance of atmospheric methane as a potent greenhouse gas and the significant contribution from ruminant enteric fermentation on methane emissions at a global scale, little effort has been made to consider the influence that different plant-based natural diets have on methane emissions in grazing systems. Heathland is an ericaceous dwarf-shrub-dominated habitat widespread across the northern hemisphere, in Europe, provides valuable ecosystem services in areas with poor soils, such as water flow regulation, land-based carbon skin, energy reservoir and habitat of key game species. We (i) measured methane emissions from red deer (Cervus elaphus) and sheep (Ovis aries) fed mixed diets of natural grass plus ericaceous species (either Calluna vulgaris or Vaccinium myrtillus) using open-circuit respiration chambers; and (ii) modelled the results to estimate methane emissions from red deer and sheep populations inhabiting heathland habitats across Europe under different scenarios of grass-based mixed diets with varying proportions of ericaceous species. Our results indicated that methane emissions per unit of digestible organic matter intake decreased as the proportion of ericaceous species in diet increased, but this relationship was complex because of the significant interaction between the proportion of ericaceous species in the diet and digestible organic matter intake. According to our estimates red deer and sheep populations across European heathlands produce 129.7 kt·y^-1 methane (se = 1.79) based on a hypothetical grass-ericaceous species mixed diet containing 30% of ericaceous species; this is 0.5% of total methane emissions from human activity across Europe (24,755 kt·y^-1), and a reduction in methane emissions of 63.8 kt·y^-1 against the same deer and sheep populations, if assumed to consume a grass-only diet. We suggest the implementation of carbon credits as a measure to value the relevance of heathland systems to promote biodiversity and its potential contribution to reduce methane emissions in ruminant grazing systems.

Effect of complete feed block with tree leaves rich in hydrolysable and condensed tannins on nutrient utilization, rumen fermentation and growth performance of lambs

Thirty lambs (Avishaan genotype, 10 weeks old, 14.0 ± 0.2 kg live weight) were randomly assigned into three equal treatment groups to study the effect of complete feed blocks (CFB; concentrate and roughage at 70:30 ratio) with three different tanniniferous tree leaves on intake and utilization of nutrients, rumen fermentation, microbial protein synthesis and growth performance. The treatments were T1 (Control), CFB1 with Vigna sinensis hay; T2, CFB2 with Acacia nilotica leaves rich in hydrolysable tannins (HT); and T3, CFB3 with Ziziphus nummularia leaves rich in condensed tannins (CT). The three CFBs were fed ad libitum to the respective groups of lambs for a period of 12 weeks. There was lower (p < .05) intake of dry matter (DM), total carbohydrates (TCHO) and fibre components in T2 compared with T1 and T3. However, the digestibility of nutrients except crude protein (CP) was higher in T2. Diet had no effect (p > .05) on the LW gain in lambs. Amongst the three groups, T3 showed enhanced N utilization with a comparable microbial protein synthesis, the lowest being in T2. The T2 group of lambs had higher propionate and lower non-glucogenic: glucogenic short-chain fatty acids ratio. It may be concluded that tanniniferous tree leaves at 30% of total mixed ration can meet the requirement of nutrients for desired post-weaning growth.

Advanced estimation and mitigation strategies: a cumulative approach to enteric methane abatement from ruminants

Methane, one of the important greenhouse gas, has a higher global warming potential than that of carbon dioxide. Agriculture, especially livestock, is considered as the biggest sector in producing anthropogenic methane. Among livestock, ruminants are the highest emitters of enteric methane. Methanogenesis, a continuous process in the rumen, carried out by archaea either with a hydrogenotrophic pathway that converts hydrogen and carbon dioxide to methane or with methylotrophic pathway, which the substrate for methanogenesis is methyl groups. For accurate estimation of methane from ruminants, three methods have been successfully used in various experiments under different environmental conditions such as respiration chamber, sulfur hexafluoride tracer technique, and the automated head-chamber or GreenFeed system. Methane production and emission from ruminants are increasing day by day with an increase of ruminants which help to meet up the nutrient demands of the increasing human population throughout the world. Several mitigation strategies have been taken separately for methane abatement from ruminant productions such as animal intervention, diet selection, dietary feed additives, probiotics, defaunation, supplementation of fats, oils, organic acids, plant secondary metabolites, etc. However, sustainable mitigation strategies are not established yet. A cumulative approach of accurate enteric methane measurement and existing mitigation strategies with more focusing on the biological reduction of methane emission by direct-fed microbials could be the sustainable methane mitigation approaches.

Effects of lespedeza condensed tannins alone or with monensin, soybean oil, and coconut oil on feed intake, growth, digestion, ruminal methane emission, and heat energy by yearling Alpine doelings

Fifty-four Alpine doelings (initial BW and age of 31.7 ± 0.38 kg and 306 ± 1.9 d, respectively) were allocated to nine treatments individually fed for ad libitum intake of 25% concentrate and 75% forage diets (DM basis). Alfalfa was the forage in the control diet. Other diets contained Sericea lespedeza as the forage, with 1.25% DM of quebracho extract included in the concentrate fraction for a dietary condensed tannin level of 8.4%. Lespedeza treatments were no additive (L) and inclusion of monensin (I) at 22 mg/kg DM (L-I), soybean oil at 3% (L-S), coconut oil at 3% (L-N), I and 3% soybean oil (L-I-S), I and 3% coconut oil (L-I-N), 1.5% soybean oil and 1.5% coconut oil (L-S-N), and I, 1.5% soybean oil, and 1.5% coconut oil (L-I-S-N). The experiment was 12 wk with two 6-wk periods. Gas exchange was determined in weeks 6 and 12, and other measures occurred in weeks 5 and 11. The control diet offered averaged 2.67% nitrogen, 43.8% neutral detergent fiber, and 8.8% acid detergent lignin, and the L diet offered averaged 2.03% nitrogen, 42.8% neutral detergent fiber, and 13.2% acid detergent lignin. There were no treatment × period interactions for digestibilities (P ≥ 0.770) or methane emission (P ≥ 0.324). There were differences (P < 0.001) between the control treatment and diets with lespedeza in intake of DM (1.46, 1.23, 1.30, 1.18, 1.32, 1.10, 1.02, 1.20, and 1.01 kg/d; SEM = 0.059), digestibility of OM (57.4%, 50.9%, 51.8%, 52.7%, 50.3%, 52.1%, 52.1%, 51.9%, and 49.8%; SEM = 1.42), and digestibility of nitrogen (59.1%, 31.2%, 32.5%, 37.1%, 31.6%, 38.3%, 30.4%, 38.4%, and 34.1% for control, L, L-I, L-S, L-N, L-I-S, L-I-N, L-S-N, and L-I-S-N, respectively; SEM = 2.21). Ruminal methane emission was less (P < 0.001) for diets with lespedeza than for the control in MJ/d (1.36, 0.76, 0.84, 0.71, 0.71, 0.66, 0.65, 0.68, and 0.68; SEM = 0.048) and relative to intake of gross energy (5.92%, 3.27%, 3.49%, 3.19%, 2.84%, 2.91%, 3.20%, 3.20%, and 3.27%; SEM = 0.165) and digestible energy (11.19%, 6.98%, 7.40%, 6.38%, 5.90%, 5.69%, 6.37%, 6.38%, and 6.70% for control, L, L-I, L-S, L-N, L-I-S, L-I-N, L-S-N, and L-I-S-N, respectively; SEM = 0.400). In conclusion, the magnitude of effect of condensed tannins from lespedeza and quebracho extract on ruminal methane emission by Alpine doelings did not diminish over time and was not markedly influenced by dietary inclusion of monensin, soybean oil, or coconut oil.

Effect of condensed tannins from Leucaena leucocephala on rumen fermentation, methane production and population of rumen protozoa in heifers fed low-quality forage

OBJECTIVE

The aim of the experiment was to assess the effect of increasing amounts of Leucaena leucocephala forage on dry matter intake (DMI), organic matter intake (OMI), enteric methane production, rumen fermentation pattern and protozoa population in cattle fed Pennisetum purpureum and housed in respiration chambers.

METHODS

Five crossbred heifers (Bos taurus×Bos indicus) (BW: 295±6 kg) were fed chopped P. purpureum grass and increasing levels of L. leucocephala (0%, 20%, 40%, 60%, and 80% of dry matter [DM]) in a 5×5 Latin square design.

RESULTS

The voluntary intake and methane production were measured for 23 h per day in respiration chambers; molar proportions of volatile fatty acids (VFAs) were determined at 6 h postprandial period. Molar concentration of VFAs in rumen liquor were similar (p>0.05) between treatments. However, methane production decreased linearly (p<0.005), recording a maximum reduction of up to ~61% with 80% of DM incorporation of L. leucocephala in the ration and no changes (p>0.05) in rumen protozoa population were found.

CONCLUSION

Inclusion of 80% of L. leucocephala in the diet of heifers fed low-quality tropical forages has the capacity to reduce up to 61.3% enteric methane emission without affecting DMI, OMI, and protozoa population in rumen liquor.

Effects of quebracho tannin extract on intake, digestibility, rumen fermentation, and methane production in crossbred heifers fed low-quality tropical grass

The aim of this work was to evaluate the effect of quebracho tannins extract (QTE) on feed intake, dry matter (DM) digestibility, and methane (CH₄) emissions in cattle fed low-quality Pennisetum purpureum grass. Five heifers (Bos taurus × Bos indicus) with an average live weight (LW) of 295 ± 19 kg were allotted to five treatments (0, 1, 2, 3, and 4% QTE/kg DM) in a 5 × 5 Latin square design. Intake, digestibility, and total methane emissions (L/day) were recorded for periods of 23 h when cattle were housed in open-circuit respiration chambers. Dry matter intake (DMI), organic matter intake (OMI), dry matter digestibility (DMD), and organic matter digestibility (OMD) were different between treatments with 0 and 4% of QTE/kg DM (P < 0.05). Total volatile fatty acid and the molar proportion of acetate in the rumen was not affected (P < 0.05); however, the molar proportion of propionate increased linearly (P < 0.01) for treatments with 3 and 4% QTE. Total CH₄ production decreased linearly (P < 0.01) as QTE increased in the diet, particularly with 3 and 4% concentration. When expressed as DMI and OMI by CH₄, production (L/kg) was different between treatments with 0 vs 3 and 4% QTE (P < 0.05). It is concluded that the addition of QTE at 2 or 3% of dry matter ration can decrease methane production up to 29 and 41%, respectively, without significantly compromising feed intake and nutrients digestibility.

Rumen methanogens and mitigation of methane emission by anti-methanogenic compounds and substances

Methanogenic archaea reside primarily in the rumen and the lower segments of the intestines of ruminants, where they utilize the reducing equivalents derived from rumen fermentation to reduce carbon dioxide, formic acid, or methylamines to methane (CH₄). Research on methanogens in the rumen has attracted great interest in the last decade because CH₄ emission from ruminants contributes to global greenhouse gas emission and represents a loss of feed energy. Some DNA-based phylogenetic studies have depicted a diverse and dynamic community of methanogens in the rumen. In the past decade, researchers have focused on elucidating the underpinning that determines and affects the diversity, composition, structure, and dynamics of methanogen community of the rumen. Concurrently, many researchers have attempted to develop and evaluate interventions to mitigate enteric CH₄ emission. Although much work has been done using plant secondary metabolites, other approaches such as using nitrate and 3-nitrooxy propanol have also yielded promising results. Most of these antimethanogenic compounds or substances often show inconsistent results among studies and also lead to adverse effects on feed intake and digestion and other aspects of rumen fermentation when fed at doses high enough to achieve effective mitigation. This review provides a brief overview of the rumen methanogens and then an appraisal of most of the antimethanogenic compounds and substances that have been evaluated both in vitro and in vivo. Knowledge gaps and future research needs are also discussed with a focus on methanogens and methane mitigation.

Effects of increasing amount of dietary Prosopis laevigata pods on performance, meat quality and fatty acid profile in growing lambs

A study with finishing lambs assessed the effect of dietary inclusion of Prosopis laevigata pods (PLPs) on performance, carcass characteristics, meat traits and fatty acid profile of subcutaneous fat. Twenty-one Rambouillet lambs (27.0 ± 3.0 kg BW) were assigned to one of three experimental diets with 0, 150 and 300 g PLP/kg DM. Evaluation of growth performance lasted 49 days. The experimental design was completely randomized and analysed with a mixed model. Lambs fed diets with 0, 150 and 300 g PLP had similar growth performance. Lambs fed diets with 300 g PLP/kg DM had better (p < 0.05) carcass yield and classification, less (p < 0.05) fat deposition and lower lightness (L*) value (p < 0.05) in meat than lambs fed diets with 0 and 150 g PLP/kg DM. Saturated fatty acids (palmitic and stearic) decreased (p < 0.05) and unsaturated fatty acids (oleic and linoleic) increased (p < 0.05) in subcutaneous fat of lambs fed diets with 150 and 300 g pods as compared with lambs not fed PLP. Prosopis laevigata pods are a safe feedstuff that can replace a third of conventional ingredients and reduce feed costs in growing lambs. Addition of PLP reduced (p < 0.05) total feed cost by 21%.

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.

In vitro screening of selected feed additives, plant essential oils and plant extracts for rumen methane mitigation

BACKGROUND

Ruminants produce large quantities of methane in their rumen as a by-product of microbial digestion of feed. Antibiotics are added to ruminant feed to reduce wasteful production of methane; however, this practice has some downsides. A search for safer and natural feed additives with anti-methanogenic properties is under way. The objective of this research was to examine selected feed additives, plant essential oils and plant extracts for their anti-methanogenic potential in the rumen using an in vitro batch fermentation system.

RESULTS

A significant reduction (P < 0.05) in methane production was observed with nine feed additives (up to 40% reduction), all eight essential oils (up to 75% reduction) and two plant extracts (14% reduction) when compared to their respective controls. Amongst these, only an algal meal high in docosahexaenoic acid, preparations of Nannochloropsis oculata, calcareous marine algae, yeast metabolites and two tannins did not inhibit microbial gas and volatile acid production.

CONCLUSIONS

The current study identified some potent dietary ingredients or plant compounds that can assist in developing novel feed additives for methane mitigation from the rumen.

Chemical composition, plant secondary metabolites, and minerals of green and black teas and the effect of different tea-to-water ratios during their extraction on the composition of their spent leaves as potential additives for ruminants

This study characterized the chemical composition of green and black teas as well as their spent tea leaves (STL) following boiling in water with different tea-to-water ratios. The green and black tea leaves had statistically similar (g/kg dry matter (DM), unless stated otherwise) DM (937 vs 942 g/kg sample), crude protein (240 vs 242), and ash (61.8 vs 61.4), but green tea had significantly higher (g/kg DM) total phenols (231 vs 151), total tannins (204 vs 133), condensed tannins (176 vs 101), and total saponins (276 vs 86.1) and lower neutral detergent fiber (254 vs 323) and acid detergent fiber (211 vs 309) than the black tea leaves. There was no significant difference between the green and black tea leaves for most mineral components except Mn, which was significantly higher in green tea leaves, and Na and Cu, which were significantly higher in black tea leaves. A higher tea-to-water ratio during extraction significantly reduced the loss of soluble compounds into water and hence yielded more nutrient-rich STL. On the basis of these analyses it appears that the green and black tea leaves alongside their STL have the potential for use as sources of protein, fiber, secondary metabolites, and minerals in ruminant diets. The presence of high levels of plant secondary metabolites in either tea leaves or their STL suggests that they may have potential for use as natural additives in ruminant diets.