• Animal Bioscience
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• v.37 no.2_spc
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• pp.360-369
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• 2024

Ruminal methane production functions as the main sink for metabolic hydrogen generated through rumen fermentation and is recognized as a considerable source of greenhouse gas emissions. Methane production is a complex trait affected by dry matter intake, feed composition, rumen microbiota and their fermentation, lactation stage, host genetics, and environmental factors. Various mitigation approaches have been proposed. Because individual ruminants exhibit different methane conversion efficiencies, the microbial characteristics of low-methane-emitting animals can be essential for successful rumen manipulation and environment-friendly methane mitigation. Several bacterial species, including Sharpea, uncharacterized Succinivibrionaceae, and certain Prevotella phylotypes have been listed as key players in low-methane-emitting sheep and cows. The functional characteristics of the unclassified bacteria remain unclear, as they are yet to be cultured. Here, we review ruminal methane production and mitigation strategies, focusing on rumen fermentation and the functional role of rumen microbiota, and describe the phylogenetic and physiological characteristics of a novel Prevotella species recently isolated from low methane-emitting and high propionate-producing cows. This review may help to provide a better understanding of the ruminal digestion process and rumen function to identify holistic and environmentally friendly methane mitigation approaches for sustainable ruminant production.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.7
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• pp.967-972
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• 2017

Objective: Two experiments were conducted to determine the effects of forage-to-concentrate (F:C) ratio on the nutrient digestibility and enteric methane ($CH_4$) emission in growing goats and Sika deer. Methods: Three male growing goats (body weight $[BW]=19.0{\pm}0.7kg$) and three male growing deer ($BW=19.3{\pm}1.2kg$) were respectively allotted to a $3{\times}3$ Latin square design with an adaptation period of 7 d and a data collection period of 3 d. Respiration-metabolism chambers were used for measuring the enteric $CH_4$ emission. Treatments of low (25:75), moderate (50:50), and high (73:27) F:C ratios were given to both goats and Sika deer. Results: Dry matter (DM) and organic matter (OM) digestibility decreased linearly with increasing F:C ratio in both goats and Sika deer. In both goats and Sika deer, the $CH_4$ emissions expressed as g/d, g/kg $BW^{0.75}$, % of gross energy intake, g/kg DM intake (DMI), and g/kg OM intake (OMI) decreased linearly as the F:C ratio increased, however, the $CH_4$ emissions expressed as g/kg digested DMI and OMI were not affected by the F:C ratio. Eight equations were derived for predicting the enteric $CH_4$ emission from goats and Sika deer. For goat, equation 1 was found to be of the highest accuracy: $CH_4(g/d)=3.36+4.71{\times}DMI(kg/d)-0.0036{\times}neutral$ detergent fiber concentrate (NDFC,g/kg)+$0.01563{\times}dry$ matter digestibility (DMD,g/kg)-$0.0108{\times}neutral$ detergent fiber digestibility (NDFD, g/kg). For Sika deer, equation 5 was found to be of the highest accuracy: $CH_4(g/d)=66.3+27.7{\times}DMI(kg/d)-5.91{\times}NDFC(g/kg)-7.11{\times}DMD(g/kg)+0.0809{\times}NDFD(g/kg)$. Conclusion: Digested nutrient intake could be considered when determining the $CH_4$ generation factor in goats and Sika deer. Finally, the enteric $CH_4$ prediction model for goats and Sika deer were estimated.

• Animal Bioscience
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• v.34 no.1
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• pp.36-47
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• 2021

Objective: This study determined the optimal ratio of whole plant corn silage (WPCS) to corn stover (stems+leaves) silage (CSS) (WPCS:CSS) to reach the greatest profit of dairy farmers and evaluated its consequences with corn available for other purposes, enteric methane production and milk nitrogen efficiency (MNE) at varying milk production levels. Methods: An optimization model was developed. Chemical composition, rumen undegradable protein and metabolizable energy (ME) of WPCS and CSS from 4 cultivars were determined to provide data for the model. Results: At production levels of 0, 10, 20, and 30 kg milk/cow/d, the WPCS:CSS to maximize the profit of dairy farmers was 16:84, 22:78, 44:56, and 88:12, respectively, and the land area needed to grow corn plants was 4.5, 31.4, 33.4, and 30.3 ha, respectively. The amount of corn available (ton DM/ha/yr) for other purposes saved from this land area decreased with higher producing cows. However, compared with high producing cows (30 kg/d milk), more low producing cows (10 kg/d milk) and more land area to grow corn and soybeans was needed to produce the same total amount of milk. Extra land is available to grow corn for a higher milk production, leading to more corn available for other purposes. Increasing ME content of CSS decreased the land area needed, increased the profit of dairy farms and provided more corn available for other purposes. At the optimal WPCS:CSS, MNE and enteric methane production was greater, but methane production per kg milk was lower, for high producing cows. Conclusion: The WPCS:CSS to maximize the profit for dairy farms increases with decreased milk production levels. At a fixed total amount of milk being produced, high producing cows increase corn available for other purposes. At the optimal WPCS:CSS, methane emission intensity is smaller and MNE is greater for high producing cows.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.12
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• pp.1768-1774
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• 2012

This study was conducted to evaluate methane ($CH_4$) and nitrous oxide ($N_2O$) emissions from livestock agriculture in 16 local administrative districts of Korea from 1990 to 2030. National Inventory Report used 3 yr averaged livestock population but this study used 1 yr livestock population to find yearly emission fluctuations. Extrapolation of the livestock population from 1990 to 2009 was used to forecast future livestock population from 2010 to 2030. Past (yr 1990 to 2009) and forecasted (yr 2010 to 2030) averaged enteric $CH_4$ emissions and $CH_4$ and $N_2O$ emissions from manure treatment were estimated. In the section of enteric fermentation, forecasted average $CH_4$ emissions from 16 local administrative districts were estimated to increase by 4%-114% compared to that of the past except for Daejeon (-63%), Seoul (-36%) and Gyeonggi (-7%). As for manure treatment, forecasted average $CH_4$ emissions from the 16 local administrative districts were estimated to increase by 3%-124% compared to past average except for Daejeon (-77%), Busan (-60%), Gwangju (-48%) and Seoul (-8%). For manure treatment, forecasted average $N_2O$ emissions from the 16 local administrative districts were estimated to increase by 10%-153% compared to past average $CH_4$ emissions except for Daejeon (-60%), Seoul (-4.0%), and Gwangju (-0.2%). With the carbon dioxide equivalent emissions ($CO_2$-Eq), forecasted average $CO_2$-Eq from the 16 local administrative districts were estimated to increase by 31%-120% compared to past average $CH_4$ emissions except Daejeon (-65%), Seoul (-24%), Busan (-18%), Gwangju (-8%) and Gyeonggi (-1%). The decreased $CO_2$-Eq from 5 local administrative districts was only 34 kt, which was insignificantly small compared to increase of 2,809 kt from other 11 local administrative districts. Annual growth rates of enteric $CH_4$ emissions, $CH_4$ and $N_2O$ emissions from manure management in Korea from 1990 to 2009 were 1.7%, 2.6%, and 3.2%, respectively. The annual growth rate of total $CO_2$-Eq was 2.2%. Efforts by the local administrative offices to improve the accuracy of activity data are essential to improve GHG inventories. Direct measurements of GHG emissions from enteric fermentation and manure treatment systems will further enhance the accuracy of the GHG data.

• Journal of Animal Science and Technology
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• v.63 no.1
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• pp.16-24
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• 2021

The suppressive effect of monensin as an ionophore-feed additive on enteric methane (CH4) emission and renewable methanogenesis were evaluated. To clarify the suppressive effect of monensin a respiratory trial with head cage was performed using Holstein-Friesian steers. Steers were offered high concentrate diets (80% concentrate and 20% hay) ad libitum with or without monensin, galacto-oligosaccharides (GOS) or L-cysteine. Steers that received monensin containing diet had significantly (p < 0.01) lower enteric CH4 emissions as well as those that received GOS containing diet (p < 0.05) compared to steers fed control diets. Thermophilic digesters at 55℃ that received manure from steers fed on monensin diets had a delay in the initial CH4 production. Monensin is a strong inhibitor of enteric methanogenesis, but has a negative impact on biogas energy production at short retention times. Effects of the activity of coprophagous insects on CH4 and nitrous oxide (N2O) emissions from cattle dung pats were assessed in anaerobic in vitro continuous gas quantification system modified to aerobic quantification device. The CH4 emission from dungs with adults of Caccobius jessoensis Harold (dung beetle) and the larvae of the fly Neomyia cornicina (Fabricius) were compared with that from control dung without insect. The cumulative CH4 emission rate from dung with dung insects decreased at 42.2% in dung beetles and 77.8% in fly larvae compared to that from control dung without insects. However, the cumulative N2O emission rate increased 23.4% in dung beetles even though it reduced 88.6% in fly larvae compared to dung without coprophagous insects. It was suggested that the antibacterial efficacy of ionophores supplemented as a growth promoter still continued even in the digested slurry, consequently, possible environmental contamination with the antibiotics might be active to put the negative impact to land ecosystem involved in greenhouse gas mitigation when the digested slurry was applied to the fields as liquid manure.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.801-813
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• 2014

A study was conducted to improve the biological activity of two medicinal plants, Eucommia ulmoides Oliv. and Glycyrrhiza uralensis, by fermentation. The biological activity was assessed by determining antibacterial, antioxidant and antimethanogenic properties. Fermentation was achieved by adding the plant materials in MRS broth at 10% (w/v) and different starter cultures at 1% (v/v). Condition for fermentation were incubation temperature of $30^{\circ}C$ and agitation at 150 rpm for 48 h. Six starter cultures, Weissella confusa NJ28 (Genbank accession number KJ914897), Weissella cibaria NJ33 (Genbank accession number KJ914898), Lactobacillus curvatus NJ40 (Genbank accession number KJ914899), Lactobacillus brevis NJ42 (Genbank accession number KJ914900), Lactobacillus plantarum NJ45 (Genbank accession number KJ914901) and Lactobacillus sakei NJ48 (Genbank accession number KJ914902) were used. Antibacterial activity was observed in L. curvatus NJ40 and L. plantarum NJ45 only as opposed to other treatments, including the non-fermented groups, which showed no antibacterial activity. Both plants showed antioxidant activity, although E. ulmoides Oliv. had lower activity than G. uralensis. However, fermentation by all strains significantly improved (p<0.05), antioxidant activity in both plants compared to non-fermented treatment. Six treatments were based on antibacterial activity results, selected for in vitro rumen fermentation; 1) non-fermented E. ulmoides, 2) fermented E. ulmoides NJ40, 3) fermented E. ulmoides NJ45, 4) non-fermented G. uralensis, 5) fermented G. uralensis NJ40, 6) fermented G. uralensis NJ45. A negative control was also added, making a total of 7 treatments for the in vitro experiment. Medicinal plant-based treatments significantly improved (p<0.05) total volatile fatty acid (VFA) concentration. Significant methane reduction per mol of VFA were observed in G. uralensis (p<0.05). Based on the present study, fermentation improves the biological activity of E. ulmoides Oliv. and G. uralensis. Fermented G. uralensis could also be applied as an enteric methane mitigating agent in ruminant animals.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.188-199
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• 2015

Nineteen tanniferous browse plants were collected from South Africa to investigate their digestibility, gas production (GP) characteristics and methane production. Fresh samples were collected, dried in forced oven, and ground and analyzed for nutrient composition. In vitro GP and in vitro organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi-automated system was used to measure GP by incubating the sample in a shaking incubator at $39^{\circ}C$. There was significant (p<0.05) variation in chemical composition of studied browses. Crude protein (CP) content of the species ranged from 86.9 to 305.0 g/kg dry matter (DM). The neutral detergent fiber (NDF) ranged from 292.8 to 517.5 g/kg DM while acid detergent fiber (ADF) ranged from 273.3 to 495.1 g/kg DM. The ash, ether extract, non-fibrous carbohydrate, neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen and CP were negatively correlated with methane production. Methane production was positively correlated with NDF, ADF, cellulose and hemi-cellulose. Tannin decreased GP, IVOMD, total volatile fatty acid and methane production. The observed low methanogenic potential and substantial ammonia generation of some of the browses might be potentially useful as rumen manipulating agents. However, a systematic evaluation is needed to determine optimum levels of supplementation in a mixed diet in order to attain a maximal depressing effect on enteric $CH_4$ production with a minimal detrimental effect on rumen fermentation of poor quality roughage based diet.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1577-1583
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• 2014

Encapsulation is a method used to protect material from certain undesirable environments, for controlled release at a more favorable time and place. Animal productivity would be enhanced if feed additives are delivered to be utilized at their site of action, bypassing the rumen where they are likely to be degraded by microbial action. A novel method of encapsulation with sesame gum was used to coat nitrate, a known enteric methane mitigating agent, and tested for the effect on methane reduction and other in vitro fermentation parameters using rumen fluid from cannulated Hanwoo steers. Orchard grass was used as basal diet for fermentation. The treatments were matrix (1.1 g sesame gum+0.4 g sesame oil cake) only, encapsulated nitrate (matrix+nitrate [21 mM]), free nitrate (21 mM), and a control that contained no additive. Analyses of fermentation parameters were done at 0, 3, 6, 9, 12, 24, and 48 h time periods. In comparison to control, both free and encapsulated nitrate produced significantly reduced (p<0.01) methane (76% less) and also the total volatile fatty acids were reduced. A significantly higher (p<0.01) concentration of ammonia nitrogen was obtained with the encapsulated nitrate treatment (44%) compared to the free form (28%) and matrix only (20%) (p = 0.014). This might suggest slow release of encapsulated nitrate so that it is fully reduced to ammonia. Thus, this pioneering study found a significant reduction in methane production following the use of sesame gum encapsulated nitrate that shows the potential of a controlled release system in enhancing sustainability of ruminant production while reducing/eliminating the risk of nitrite toxicity.

• Animal Bioscience
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• v.37 no.2
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• pp.173-183
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• 2024

Objective: This study aimed to evaluate whether the methane (CH₄) to carbon dioxide (CO₂) ratio (CH₄/CO₂) and methane-related traits obtained by the sniffer method can be used as indicators for genetic selection of Holstein cows with lower CH₄ emissions. Methods: The sniffer method was used to simultaneously measure the concentrations of CH₄ and CO₂ during milking in each milking box of the automatic milking system to obtain CH₄/CO₂. Methane-related traits, which included CH₄ emissions, CH₄ per energy-corrected milk, methane conversion factor (MCF), and residual CH₄, were calculated. First, we investigated the impact of the model with and without body weight (BW) on the lactation stage and parity for predicting methane-related traits using a first on-farm dataset (Farm 1; 400 records for 74 Holstein cows). Second, we estimated the genetic parameters for CH₄/CO₂ and methane-related traits using a second on-farm dataset (Farm 2; 520 records for 182 Holstein cows). Third, we compared the repeatability and environmental effects on these traits in both farm datasets. Results: The data from Farm 1 revealed that MCF can be reliably evaluated during the lactation stage and parity, even when BW is excluded from the model. Farm 2 data revealed low heritability and moderate repeatability for CH₄/CO₂ (0.12 and 0.46, respectively) and MCF (0.13 and 0.38, respectively). In addition, the estimated genetic correlation of milk yield with CH₄/CO₂ was low (0.07) and that with MCF was moderate (-0.53). The on-farm data indicated that CH₄/CO₂ and MCF could be evaluated consistently during the lactation stage and parity with moderate repeatability on both farms. Conclusion: This study demonstrated the on-farm applicability of the sniffer method for selecting cows with low CH₄ emissions.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.735-746
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• 2016

This study was conducted to investigate the antibacterial, antioxidant, and in vitro greenhouse gas mitigation activities of fermented Scutellaria baicalensis Georgi extract. Seven starter cultures were used, comprising four of lactic acid bacteria and three of Saccharomyces cerevisiae. Ten grams of S. baicalensis Georgi powder was diluted in 90 mL autoclaved MRS broth. Each seed culture was inoculated with 3-10% (v/v) S. baicalensis Georgi MRS broth and incubated at $30^{\circ}C$ for 48 h. Among the starter cultures used, only Lactobacillus plantarum EJ43 could withstand the fermentation conditions. This fermentation broth was dried and extracted with ethanol to assess its antibacterial, antioxidant, and in vitro methane mitigation activities. The extract of S. baicalensis Georgi fermented by L. plantarum EJ43 (SBLp) showed higher antibacterial activity (bigger clear zone) compared to the unfermented S. baicalensis Georgi extract (SB0). SBLp also presented 1.2 folds higher antioxidant activity than SB0. During in vitro rumen fermentation, SBLp showed reduction in methane production compared to SB0 or the control. In conclusion, fermentation by L. plantarum EJ43 may enhance antibacterial and antioxidant activities of S. baicalensis Georgi and decrease enteric methane production.