The objective of the present study was to investigate the effects of different red seaweeds on in vitro rumen fermentation characteristics and methane gas production. Five species of red seaweed (Chrysymenia wrughtii Yamada, CW; Hypnea sp., Hypnea sp.; Chondria crassicaulis, CC; Gelidium vagum Okamurae, GV; Hypnea saidana Holmes, HS) were obtained from National Institute of Fisheries Science (NIFS) in South Korea. The collected red seaweeds were washed for 3 minutes, and then samples were freeze-dried and ground to a size of a 1 millimeter. The buffered ruminal fluid (50 mL) was incubated with substrates and seaweeds (5% of substrates) at 39℃ for 48 hours. Total gas production was lower than red seaweed treatments excluding the CW treatment (p<0.05; 63.25 mL). Methane production was the lowest in CC treatment (p<0.05; 9.93 mL/g of digestible dry matter). The rumen pH of the red seaweed treatments ranged from 5.98 to 6.08, which was significantly the lowest in the GV treatment (p<0.05; 5.98). There was no significant difference in the total VFA concentration, but propionate (27.53%) was significantly highest in the CW treatment, whereas acetate (53.14%), iso-valerate (3.52%), valerate (1.72%), and A:P ratio (1.93) were significantly lowest (p<0.05). In conclusion, among the five species of red seaweeds, Chondria crassicaulis reduced in vitro methane production without negative effects on dry matter digestibility. Future studies will be needed to determine the optimal inclusion level of Chondria crassicaulis as feed additive to reduce enteric methane production.

This study aimed to investigate the effects of various washing pre-treatments of native Codium fragile as a feed additive on in vitro ruminal fermentation and CH4 production in ruminants. Seaweed was included at 0.5% dry matter (DM) based on the experimental feed (forage : concentrate = 3:7). Treatment groups were classified as follows: experimental feed (C), no washing (T1), washing at 0°C (T2), washing at 22°C (T3) and washing at 70°C (T4) each immersed for 6 minutes in distilled water. The pH consistently fell within the ruminal stability range. In vitro dry matter digestibility was significantly highest in T2, T3, T4 and C, T4 was the lowest at 48 h (p<0.05). NH3-N concentration was significantly highest in T4 at 48 h (p<0.05). Total gas production at 48 h was 19% lower in T4 compared to C (p<0.01). CH4 production (mL/g DM) at 48 h was lower in all treatment groups compared to C, with T3 showing a 31% reduction (p<0.01). Similarly, CH4 production (mL/g dry matter degradability, DMD) at 48 h was 39% lower for T3 compared to C (p<0.01). At 24 h, total VFA was significantly highest in T1 and T4 (p<0.05). The proportions of acetate was significantly highest in C and T3 was the lowest at 48 h (p<0.01). The proportions of propionate was significantly highest in T3 and C was the lowest at 48 h (p<0.01). The acetate to propionate ratio was singnificantly highest in C at 48 h (p<0.01). The proportions of butyrate at 24 h was lower for T3 compared to C (p<0.05). Therefore, this study confirms that Codium fragile can reduce CH4 production when used as a feed additive for ruminants and this effect is not significantly influenced by the washing pre-treatment. However, if washing process is necessary, washing at 22°C is the most appropriate method to remove foreign objects.

The study aimed to investigate the impact of varying levels of neutral detergent-soluble fiber (NDSF) in Hanwoo growing cattle diets on rumen fermentation and methane (CH4) emissions. An in vitro rumen fermentation experiment utilized feeds with different NDSF levels, incorporating ingredients such as corn grain, soybean meal, soybean hulls, palm kernel meal, beet pulp and timothy hay. The NDSF contents in the diets were 9.02% (T1), 10.09% (T2), 12.42% (T3) and 14.63% (T4). In vitro dry matter digestibility (IVDMD) at 48 h was 7.4% higher for T4 compared to T1 (p<0.05). Total gas production at 48 h was 6.6% higher for T4 than T1 (p<0.05). CH4 production significantly decreased at 9 h and 12 h for T1 and T2 (p<0.05). At 48 h, CH4 production was 5.6% higher for T4 compared to T1 and 6.7% higher compared to T2 (p<0.05). At 12 h ans 24 h, the ammonia nitrogen concentration of T4 was approximately 33.1% and 40.4% lower, respectively, compared to T1 (p<0.05). The acetate to propionate ratio at 48 h was approximately 18.8% higher for T4 than T1 (p<0.05). From 9 h to 48 h, the proportions of butyrate and valerate were significantly higher for T4 (p<0.05). At 48 h, the dominant phylum in T4's rumen microbial community was Candidatus Thermoplasmatota Methanomassiliicoccus, an Archaea. Therefore, this study confirmed that increasing the NDSF content in growing Hanwoo cattle diets up to 12.42% increases IVDMD without increasing CH4 emissions, which is expected to positively impact Hanwoo productivity.

The thermocatalytic decomposition of methane is a promising method for hydrogen production. To determine the cause of carbonaceous catalyst deactivation and to produce high-value carbon, methane decomposition behavior and deactivated catalysts were analyzed. The surface properties and crystallinity of a commercial activated carbon material, MSP20, used as a methane decomposition catalyst, varied with the reaction time at a reaction temperature of 900 °C. During the initial reaction, MSP20 provided a methane conversion of ≥ 50%; however, the catalyst exhibited rapid deactivation as crystalline carbon grew at surface defects; after 15 min of reaction, approximately 33% methane conversion was maintained. With increasing reaction time, the specific surface area of the catalyst decreased, whereas crystallinity increased. The R-square value of the conversion–crystallinity relationship was significantly higher than that of the conversion–specific surface area relationship; however, neither profile was linear. The activity of the activated carbon catalyst for methane decomposition is mainly determined by the complex actions of the specific surface area and defect sites. The activity was maintained after an initial sharp decline caused by the continuous growth of crystalline carbon product. This study presents the application of carbonaceous catalysts for the decomposition reaction of methane to form COx- free hydrogen, while simultaneously yielding porous carbon materials with an improved electrical conductivity.

본 연구는 조사료 원료인 마늘 껍질의 사료적 가치와 메탄 발생량을 조사하기 위해 in vitro 발효 실험을 수행하였다. Garlic husk를 제외하고 국내에서 널리 사용되는 4가지 조사료 원료(Oat hay, Annual ryegrass, Timothy, Tall fescue)를 실험의 처리구로 구성하였다. In vitro 48 시간 발효 후 건물 소화율, 섬유소 소화율, 암모니아태 질소, 휘발성 지방산, pH, 메탄 발생량을 평가하였다. 가스 발생량은 3, 6, 9, 12, 24, 36 및 48 시간에 각각 측정되었다. 최종 가스 발생량에서 Oat hay가 유의적으로 가장 높았다(p<0.01). Garlic husk는 처리구 중 가장 높은 메탄 발생량을 나타내었다(p<0.01). Garlic husk의 건물 소화율은 Oat hay보다 유의적으로 낮았지만 Annual ryegrass, Timothy, Tall fescue보다 높았다(p<0.01). 섬유소 소화율은 Annual ryegrass에서 가장 낮았다(p<0.01). 총 휘발성 지방산 생성량은 Oat hay에서 가장 높았고(p<0.01), Garlic husk, Timothy, Tall fescue는 유사하였다. 본 연구의 in vitro 발효 성상과 메탄 발생량을 고려할 때, Garlic husk는 국내 주요 조사료를 대체할 영양적 가치를 포함하고 있으나 메탄 저감 효과는 미미할 것으로 추정된다.

The objective of this study was to evaluate effects of feeding methods on in vitro ruminal fermentation, total gas and methane production in Hanwoo steers. Six Hanwoo steers fitted with rumen cannula (430 ± 21 kg of body weight) were randomly assigned to one of three feeding systems: 1) feeding forage 1 hour after concentrate, 2) feeding concentrate 1 hour after forage, 3) feeding mixed ration. Rumen fluid sampled from each animals was incubated 24 hours with maize or timothy substrates in in vitro. Ruminal pH was increased in feeding method 2 or maize substrate than that of other methods or timothy substrate (P < 0.001). The production of total volatile fatty acid, acetate, propionate, butyrate, and valerate were increased when steers fed diets using feeding method 1 or rumen fluid was incubated with maize substrate (P < 0.001). Increased production of total gas and methane was observed in feeding method 1 and maize substrate compared to those of other methods or timothy substrate (P < 0.001). Due to the inconsistent results between ruminal fermentation and gas production in this study, further research is required to estimate effects of feeding method on enteric fermentation and gas production in in vivo.

막 분리 운전방식에 따른 음폐수 소화가스의 도시가스용 바이오메탄 생산연구를 상업용 시설을 대상으로 수행하였다. 연구결과 바이오메탄의 순도는 4SBR과 3SDR 모두 98.9%를 달성할 수 있었다. 소화가스 내 메탄 회수율은 4SBR 88.1%, 3SDR 79.4%이었고, 처리 소화가스량 대비 바이오메탄 생산율도 4SBR이 53.5%로 3SDR의 49.4%보다 높았다. 그러나 막 분리시설에 공급되는 가스 중 반송 가스의 비율은 4SBR이 56.5%로 3SDR 보다 두 배가량 컸으며, 이로 인해 최대 처리량에 있어서는 3SDR이 양호한 결과를 보였다. 따라서 소화가스 200 Nm3/day 이하는 4SBR, 240 Nm3/day 이상에서는 3SDR이 경제성이 좋은 것으로 판단되었다. 공정 운전변수들의 평균값 대비 운전 값들의 상대편차는 전반적으로 4SBR이 컸으며, 또한 주 운전조절 수단인 바이오메탄 인출압력 대비 주요 지표들의 상관관계에 있어서는 3SDR가 보다 직접적인 관계를 보여주었다.

TMR 급여와 분리급여가 반추위 메탄발생량 변화에 미치는 효과를 연구한 사례가 많지 않다. 본 실험은 1일 실험사료를 체중의 1.8%(실험 1) 그리고 2.4%(실험 2) 수준에서 급여 하면서 triplicated 2×2 Latin square design을 이용하여 실험을 수행하였다. 각 실험에는 6마리의 Holstein steer를 이용하였고 2개의 군으로 나누어 각각 TMR 급여 또는 분리급여를 하였다. 공시 사료의 농후사료와 조사료 비율은 73% 그리고 27%이었다. 두 실험 모두 사료급여 방식 간의 1일 메탄발생량 차이가 없었다. 현재까지 보고된 국내 연구와 본 연구에서 얻어진 개체 별 1일 건물섭취량과 1일 메탄발생량과의 관계를 분석한 결과, 메탄발생량 (g/d) = 11.5 (±1.3) × 건물섭취량 (kg/d) + 14.2, R2 = 0.73, p<0.001의 회귀식을 유도하였다.

The present experiment was designed to investigate the effects of extruded linseed supplementation on methane production in Holstein steers. Four Holstein steers fitted with permanent cannulas were assigned to two dietary treatments in a duplicated 2 × 2 Latin square design: a control diet consisting of tall fescue straw (65%) and concentrate (35%), and a treatment diet supplemented with 3.8% extruded linseed by replacing a part of ingredients in the concentrate of the control diet. The concentrates of the control and the treatment diet were isoenergetic and isonitrogenous. Extruded linseed supplementation did not affect dry matter intake but significantly (P<0.05) increased the intake of lipid. Rumen pH was significantly (P<0.05) lower for control than for treatment. Although there was no significant difference between treatments, the concentration of total VFA in control was 21% higher than in treatment. The concentrations of acetic acid, propionic acid and butyric acid were not different between treatments. Extruded linseed supplementation significantly (P<0.05) reduced methane output(g/d) and emission factor. Methane conversion rate was lower for treatment than for control but no significant difference was found. The results of the present study showed that extruded linseed supplementation in the diet of Holstein steers could reduce methane output.

This study was conducted with two ruminally cannulated Holstein steers to examine the effect of micronized and steam flaked corn on ruminal fermentation characteristics. The in situ dry matter degradability after 48 h incubation was the highest (P<0.05) at micronized corn (2.5 mm thickness) compared with steam flaked corn treatments. The steam flacked corn (3.3 mm thickness) was degraded lower (P<0.05) than the 2.9 and 3.1 mm thickness of steam flacked corn. Effective dry matter degradability and the rate of constant were the highest (P<0.05) at micronized corn (2.5 mm thickness) compared with steam flaked corns as well. The in vitro dry matter degradability after 48 h incubation was tended to higher (P=0.088) at micronized corn (2.5 mm thickness) than steam flaked corns, whereas there is no significantly difference between steam flaked corn treatments. Total volatile fatty acid concentration was higher at steam flaked corn (2.9 mm thickness) than micronized corn (2.5 mm thickness) and steam flaked corn (3.1 and 3.3 mm thickness). The acetate : propionate ratio was the highest (P=0.008) at steam flaked corn (2.9 mm thickness) and the lowest (P=0.008) at micronized corn (2.5 mm thickness). Total gas and methane production after 48h ruminal incubation was the highest (P=0.001) at micronized corn (2.5 mm thickness) compared with steam flaked corns. According to these results, the thickness of steam flaked corn as resulted corn processing is believed to do not affect methane production. However, further study is needed to better understand the present results to verify the correlation between corn processing method and their thickness on methane production using the same thickness corns by difference processing methods.

The objectives of the present study were to investigate the effect of five chemical inhibitors on methane production of the pure cultures of methanogens. To examine the methanogenesis inhibition by 2-bromoethane sulfonic acid (BES), 3-bromopropane sulfonic acid (BPS), lumazine, propynoic acid and ethyl 2-butynoate, they were added into the pure cultures of Methanobacterium formicicum KOR-1 and KOR-12, Methanoculleus bourgensis KOR-2, Methanosarcina mazei KOR-3, KOR-7, KOR-9 and KOR-10, Methanosarcina vacuolata (DSM 1232), Methanobacterium bryantii (ATCC 33272), Methanosarcina mazei (ATCC BAA159) and Methanosarcina barkeri (ATCC 43240). Each methanogen was anaerobically incubated at 39℃ for 6 and 10 days, and then methane gas production was measured. All methanogens were sensitive to BES, lumazaine and ethyl 2-butynoate and as the addition levels of the chemicals increased, the methanogenesis was linearly reduced. BPS and propynoic acid failed to inhibit any of the methanogens. There were important differences among species of methanogens regarding their sensitivity to the different inhibitors. In general, the strains of Methanosarcina species were the most resistant to BES, lumazaine and ethyl 2-butynoate and the strains of Methanobacteriales order the least resistant. The different resistances to chemical inhibitors may be caused by different cell membrane structure, substrate utilization for methanogenesis and competition with other microorganisms for electron receptors. In conclusion, differences among methanogens habituating in anaerobic ecosystems, such as the rumen of ruminants regarding their resistance to chemical inhibitors should be considered when strategies of inhibition of methanogenesis are designed.

The objective of this study was to determine how feeding forage and concentrate separately (SF) or as a total mixed ration (TMR) affects enteric methane production of cattle. Six Holstein steers (203 ± 22.5 kg) were used in a 2 × 3 changeover design experiment. Experimental diets (TMR and SF) consisted of compound feed, timothy hay and soybean curd residue in a ratio of 40:48:12, respectively, and diets were fed at 10% of metabolic body weight, on an as-fed basis. There were no differences in dry matter intake and enteric methane production (g/d) between SF and TMR but the methane conversion rate (methane energy/GE intake) of TMR was significantly higher (p=0.05) than that of SF. The mean methane emission factor (kg/head/year) and conversion rate of the two treatments were 21.4 and 0.05, respectively. There was a strong relationship between metabolic body weight and enteric methane production (p<0.001). At the present time, further studies may be necessary in order to establish the effects of TMR and SF on enteric methane production.

This study was conducted to evaluate effects of supplementation of Bifidobacterium ruminantium on in vitro ruminal fermentation and methane production. Ruminal fermentation characteristics of Timothy hay (C1), whole barley (C2), Timothy hay + B. ruminantium (T1) and whole barley + B. ruminantium (T2) were evaluated at 0, 3, 6, 9, 12, 24 and 48 h incubation at 39℃. The amount of B. ruminantium culture added into T1 and T2 was 0.3 ml. The pH values ranged from 5.99 to 6.83 in all the treatments. Concentration of NH3-N of C2 and T2 was higher than C1 and T1 at 48 h (p<0.05). The total gas production of C2 and T2 was higher than C1 and T1 at 9 h (p<0.05). The total methane production of treatments with B. ruminantium was not significantly different at 24 and 48 h (p<0.05). Concentration of lactic acid was significantly different between both substrates (p<0.05). Therefore, B. ruminantium supplementation was determined to be insignificant in the in vitro ruminal fermentation and methane production, while a further study was required to investigate relation to lactic acid production with different forage sources.

본 시험은 질산염함유 식물 추출물을 이용하여 in vitro 반추위 발효성상 및 반추위 메탄 발생에 미 치는 영향을 알아보기 위해 수행되었다. 공시재료는 감자, 당근, 배추, 상추 및 시금치 추출물을 사용하 였으며, 발효 기질은 2mm로 분쇄된 timothy 0.3g을 사용하였다. In vitro 실험은 조사료(timothy) 및 배합사료를 6:4의 비율로 급여한 반추위 cannnula가 시술된 한우 암소에서 채취하였다. 반추위액과 McDougall’s buffer를 1:2의 비율로 혼합한 발효액을 0.3g timothy와 식물 추출물이 담긴 50mL serum bottle에 혐기상태로 20mL 분주한 뒤, 39℃에서 9, 12, 24, 48시간 동안 발효하였다. pH는 발 효 시간이 증가함에 따라 점점 감소하며, 6.31~6.96으로 정상범위였다. 건물 소화율은 9시간 배추 추 출물구에서 유의적으로 낮았고, 암모니아 농도는 감자, 배추, 상추 추출물구에서 대조구에 비해 첨가구 에서 유의적으로(p<0.05) 낮았으며, 반추위 미생물 성장량은 발효 24시간대의 당근 추출물구에서 높았 다(p<0.05). Acetate와 propionate 농도는 대조구에 비해 첨가구에서 유의적으로 낮았으며(p<0.05) butyrate 농도는 첨가구간에 발효시간별로 각각 다른 양상을 보였다. 총 가스 발생량은 발효 12시간 및 24시간대에서 배추, 상추, 시금치 추출물구에서 유의적으로(p<0.05) 낮았으며, 메탄 발생량은 감자, 배 추, 시금치 추출물구가 대조구에 비해 유의적으로(p<0.05) 낮았고, 이산화탄소 발생량 또한 첨가구에 비해 대조구에서 유의적으로(p<0.05) 낮았다. 결과적으로 본 시험에 사용된 5종의 질산염 함유 식물 추 출물은 반추위 발효에 악영향을 미치지 않으면서 메탄저감 효과를 나타내었다. 특히 배추 추출물은 반 추위내 메탄발생을 저감시킬 수 있는 식물추출물로서 가능성이 높은 것으로 사료된다.