• Asian-Australasian Journal of Animal Sciences
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• 제12권3호
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• pp.371-375
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• 1999

The present study was conducted to evaluate the mottgrass alone and in combination with berseem (Trifolium alexandrinum) at different intake levels to determine the lag time, rate and extent of digestion of DM and NDF of mottgrass. Four ruminally cannulated buffalo calves were used in a $4{\times}4$ Latin Square Design with $2{\times}2$ factorial arrangement of treatments. The two factors were forage intake levels (ad libitum versus restricted) and forage source (mottgrass versus mottgrass plus 25% berseem). Four dietary treatment consisted of 1) ad libitum mottgrass, 2) restricted feeding of mottgrass, 3) ad libitum mottgrass plus berseem with a ratio of 3:1 and 4) restricted mottgrass plus berseem in a ratio of 3:1 Calves fed ad libitum mottgrass supplemented with 25% berseem consumed 25% more DM and 15 % more NDF than those fed mottgrass only. The in situ DM digestibility, the lag time and extent of digestion were not affected by intake level. However, rate of disappearance was greater in restricted fed animals than those fed ad libitum. This increased rate could be due to greater concentration of fibrolytic bacteria in restrict fed animals. The DM digestibility was greater (64.1%) in calves fed mottgrass supplemented with 25% berseem than those fed mottgrass only (57.7%). The reduced mottgrass DM digestion may be due to its higher NDF contents. The NDF digestibility, the lag and extent of NDF digestion were not affected by varying intake levels. However, rate of digestion of NDF was higher in restricted fed animals than those of ad libitum fed animals. The NDF digestibility was greater (58.4%) in calves fed mottgrass supplemented with 25% berseem than those fed mottgrass (48.7%) only.

• Advances in environmental research
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• 제10권1호
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• pp.87-103
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• 2021

Anaerobic digestion (AD) refers to the biological process which can convert organic substrates to biogas in the absence of oxygen. The aim of this study was to determine the capability of feedstock to produce biogas and to quantify the biogas yield from different feedstocks. A co-digestion approach was carried out in a continuous stirred tank reactor operated under mesophilic conditions and at a constant organic loading rate of 0.0756 g COD/ L.day, with a hydraulic retention time of 25 days. For comparison, mono-digestion was also included in the experimental work. 2 L working volumes were used throughout the experimental work. The seed culture was obtained from composting as substrate digestion. When the feedstock was added to seeding, the biogas started to emit after three days of retention time. The highest volume of biogas was observed when the seeding volume used for 1000mL. However, the lowest volume of biogas yield was obtained from both co-digestion reactors, with a value of 340 mL. For methane yield, the highest methane production rate was 0.16 L CH4/mg. The COD with yield was at 8.6% and the lowest was at 0.5%. The highest quantity of methane was obtained from a reactor of Euphorbiaceae peel with added seeding, while the lowest methane yield came from a reactor of Euphorbiaceae stems with added seeding. In this study, sodium bicarbonate (NaHCO3) was used as a buffering solution to correct the pH in the reactor if the reactor condition was found to be in a souring or acidic condition.

• 상하수도학회지
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• 제27권6호
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• pp.815-826
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• 2013

Using a developed mathematical model and calibrated kinetic constants, numerical experiments for a aerobic digestion of wastewater sludge by SBR aerobic digestion process combined with ultrasonication (USSBR) were performed in this study. It simulated well the phenomena of the decomposition of particulate organics and the release of organic nitrogen and transformation. To achieve 40 % of particulate organics removal, USSBR process requires only 6 days of SRT and 14 W/L of ultrasonic power whereas SBR aerobic digestion process requires 12 days of SRT. Based on the model simulation results, an empirical equation was presented here. This equation will be used to predict digestion efficiency for the given variables of SRT and ultrasonic power dose. USSBR aerobic digestion process can reduce the nitrogen concentration. The optimal operation strategy for the simultaneous removal of solids and soluble nitrogen in this process is estimated to 7 days of SRT with 14 W/L of ultrasonic power dose while anoxic period was 6 hours out of 24 hours of cycle time. In this condition, 40 % of particulate organics as well as 36 % of total nitrogen will be removed and the soluble nitrogen concentration of the centrate will be lower less then 40 mg/L.

• 한국식품과학회지
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• 제10권4호
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• pp.394-397
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• 1978

한우(韓牛)의 round muscle에 papain으로 일차(一次) 분해(分解)시킨 후 pepsin에 의한 in vitro소화율(消化率)과 소화과정중(消化過程中) 생성(生成)되는 amino 태(態)-N의 경분적(經分的)인 변화(變化)를 실험(實驗)한 결과(結果)는 다음과 같다. 1. 효소처리구(酵素處理區)가 대조구(對照區)에 비(比)하여 소화율(消化率)도 높았으며 소화시간(消化時間)도 단축되었다. 2. 효소처리구(酵素處理區)는 소화과정중(消化過程中) $6{\sim}10$분간(分間)사이에 소화율(消化率)이 현저하게 증가(增加)하였다. 3. amino태(態)-N는 소화율(消化率)과 소화시간(消化時間)에 거의 비슷하게 증가(增加)하였다. 4. 대조구(對照區)에 비(比)하여 효소처리구(酵素處理區)가 amino태(態)-N 생성량(生成量)이 현저하게 높았으며$2{\sim}8$시간(時間)사이에서 그 증가율(增加率)이 가장 높았다.

• 한국환경과학회지
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• 제9권1호
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• pp.75-80
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• 2000

Kinetic data for the acid phase anaerobic digestion were presented in this study and the constants were determined with acid production rate and gas production rate. Process models based on continuous culture theory were used to describe the characteristics of the acid forming microorganisms and to enable further development toward utilization of the process in a more rational manner. Acid phase digestion can be separated with appropriate manipulation of hydraulic retention time in anaerobic digestion. Kinetic analysis of data from the various hydraulic retention times using a phase specific model obtained form the acid phase indicated maximum specific growth rate of 0.40/h, saturation constant of 2,000mgCOD.$\ell$, yield coefficient of 0.35 mgVSS/msCOD utilized and decay constant of 0.04/h for the acid production rate. Similar analysis of data for the gas production rate indicated maximum specific growth rate of 0.003/h, saturation constant of 2,200mgCOD/$\ell$, yield coefficient of 0.035 mgVSS/mgCOD utilized and decay constant of 0.06/h.

• Asian-Australasian Journal of Animal Sciences
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• 제15권11호
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• pp.1659-1676
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• 2002

Ruminant animals develop a diverse and sophisticated microbial ecosystem for digesting fibrous feedstuffs. Plant cell walls are complex and their structures are not fully understood, but it is generally believed that the chemical properties of some plant cell wall compounds and the cross-linked three-dimensional matrix of polysaccharides, lignin and phenolic compounds limit digestion of cell wall polysaccharides by ruminal microbes. Three adaptive strategies have been identified in the ruminal ecosystem for degrading plant cell walls: production of the full slate of enzymes required to cleave the numerous bonds within cell walls; attachment and colonization of feed particles; and synergetic interactions among ruminal species. Nonetheless, digestion of fibrous feeds remains incomplete, and numerous research attempts have been made to increase this extent of digestion. Exogenous fibrolytic enzymes (EFE) have been used successfully in monogastric animal production for some time. The possibility of adapting EFE as feed additives for ruminants is under intensive study. To date, animal responses to EFE supplements have varied greatly due to differences in enzyme source, application method, and types of diets and livestock. Currently available information suggests delivery of EFE by applying them to feed offers the best chance to increase ruminal digestion. The general tendency of EFE to increase rate, but not extent, of fibre digestion indicates that the products currently on the market for ruminants may not be introducing novel enzyme activities into the rumen. Recent research suggests that cleavage of esterified linkages (e.g., acetylesterase, ferulic acid esterase) within the plant cell wall matrix may be the key to increasing the extent of cell wall digestion in the rumen. Thus, a crucial ingredient in an effective enzyme additive for ruminants may be an as yet undetermined esterase that may not be included, quantified or listed in the majority of available enzyme preparations. Identifying these pivotal enzyme(s) and using biotechnology to enhance their production is necessary for long term improvements in feed digestion using EFE. Pretreating fibrous feeds with alkali in addition to EFE also shows promise for improving the efficacy of enzyme supplements.

• 한국식품영양과학회지
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• 제45권4호
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• pp.533-541
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• 2016

페놀화합물의 함량이 높다고 알려진 카카오(powder)로부터 카카오 추출물(CE)을 획득한 후, CE가 pancreatic lipase의 활성에 미치는 영향과 CE를 함유한 emulsion의 aging에 의한 가수분해율 변화를 살펴보기 위하여 두 가지 형태의 기질을 사용한 pH-stat digestion model을 이용하였다. Type I 의 경우 소화액에 CE와 콩기름을 첨가하여 emulsion을 제조하였으며 aging time(0, 5, 24시간)에 따른 가수분해 변화를 살펴보았다. CE를 첨가하였을 때의 가수분해율은 CE를 첨가하지 않았을 때와 큰 차이를 보이지 않아 CE가 pancreatic lipase 활성에 영향을 주지 않았다고 판단된다. 그러나 aging time이 지남에 따라 CE를 첨가하였을 때와 CE를 첨가하지 않았을 때의 가수분해율 모두 감소하였다. 이는 CE의 영향보다는 aging time이 길어짐에 따라 emulsion의 안정도가 낮아져 지방구 크기가 증가하여 가수분해율이 모두 감소한 것으로 생각되고, 따라서 이 모델에서는 CE에 의한 가수분해 저하가 크지 않았다. 한편 type II의 경우 먼저 콩기름과 CE, Tween 20를 혼합하고 고압균질기를 사용하여 micro-emulsion을 제조한 후, 이를 기질로 하여 aging time(0, 2, 4, 7, 18, 43일)에 따른 가수분해율 변화를 살펴보았다. 그 결과 aging time에 따라 CE를 첨가하지 않은 control과 CE를 첨가한 CE-emulsion의 가수분해율이 감소하였는데, 특히 control보다 CE-emulsion이 더 많이 감소하여 43일에는 control의 ${\Phi}$ max가 92.13%(0일, 96.53%)였으나 CE-emulsion은 77.69%(0일, 97.91%)를 보이면서 CE-emulsion의 가수분해 반응이 control에 비해 낮았다. 다른 kinetic parameter(k value, $t_{1/2}$ 등)에서도 이와 유사한 경향을 나타냈다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권2호
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• pp.230-236
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• 2018

Objective: Two ex vivo experiments were conducted to verify the effect of barley grain (Nusrat cultivar) treated with alkaline compounds (AC) including alum, ammonium, and sodium hydroxide or cation-exchanged organic extracts (OE) prepared from alfalfa hay, sugar beet pulp and Ulva Fasciata, on extent and digestion of starch. Methods: In the first study, the in vitro first order disappearance kinetic parameters of dry matter (DM), crude protein (CP) and starch were estimated using a non-linear model ($D_{(t)}=D_{(i)}{\cdot}e^{(-k_d{\cdot}time)}+I$, where: $D_{(t)}$ = potentially digestible residues at any time, $D_{(i)}$ = potentially digestible fraction at any time, $k_d$ = fractional rate constant of digestion (/h), I = indigestible fraction at any time). In the second experiment, the ruminal and post-ruminal disappearance of DM, CP, and starch were determined using in situ mobile nylon bag. Results: Barley grains treated with alum and alfalfa extract had a higher constant rate of starch digestion (0.11 and 0.09/h) than others. Barley grain treated with OE had a higher constant rate of CP digestion and that of treated with AC had a higher constant rate of starch digestion (0.08 and 0.11/h) compared with those of the other treatments. The indigestible fraction of starch treated with alum and sugar beet pulp extract was higher than that of the control group (0.24 and 0.25 vs 0.21). Barley grain treated with AC and OE had significant CP disappearance in the rumen, post-rumen and total tract, and also starch disappearance for post-rumen and total tract compared with the untreated (p<0.001). Conclusion: This study demonstrated that AC and OE might have positive effects on the starch degradation of the barley grain. In addition, treating barley grain with alum and sugar beet pulp extract could change the site and extend digestion of protein and starch.

• 유기물자원화
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• 제27권3호
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• pp.27-39
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• 2019

본 연구에서는 음식물류 폐기물과 하수슬러지의 효과적인 병합 혐기성 처리를 위한 열화학적 가수분해 방법의 최적 조건 평가와, 열화학적 가수분해에 따른 병합 혐기성 소화 효율에 대해 평가 하였다. 열화학적 가수분해는 온도 (80, 100, 120, 140, 160, $180^{\circ}C$)와 NaOH (5, 20, 40, 60, 100 meq/L) 조건에 따른 solubilization COD, CST(Capillary Suction Time), TTF(Time to Filter), volatile fatty acids (VFAs) 등에 대해 평가를 하였으며, 병합 혐기성 소화 효율평가는 biochemical methane potential (BMP) test를 통해 평가하였다. 실험결과 음식물류폐기물과 하수슬러지의 열화학적 가수분해 시 온도 $140^{\circ}C$, NaOH 60 meq/L에서 solubilization COD 20 % 이상, CST와 TTF가 60초 이하, VFAs 농도가 12,000 mg-COD/L 이상으로 최적조건으로 규명되었다. 병합 혐기성 소화 결과도 열화학적 가수분해 조건과 동일한 조건에서 가스발생량이 가장 높았다. 따라서, 음식물류폐기물과 하수슬러지의 효과적인 병합혐기성소화를 위한 열화학적 가수분해 전처리 조건은 온도 $140^{\circ}C$, NaOH 주입농도 60 meq/L라 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제20권2호
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• pp.200-207
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• 2007

In vitro rumen incubation studies were conducted to determine effects of initial pH on bacterial attachment and fiber digestion. Ruminal fluid pH was adjusted to 5.7, 6.2 and 6.7, and three major fibrolytic bacteria attached to rice straw in the mixed culture were quantified with real-time PCR. The numbers of attached and unattached Fibrobacter succinogenes, Ruminococcus flavefaciens and Ruminocococcus albus were lower (p<0.05) at initial pH of 5.7 without significant difference between those at higher initial pH. Lowering incubation media pH to 5.7 also increased bacterial numbers detached from substrate regardless of bacterial species. Dry matter digestibility, gas accumulation and total VFA production were pH-dependent. Unlike bacterial attachment, maintaining an initial pH of 6.7 increased digestion over initial pH of 6.2. After 48 h in vitro rumen fermentation, average increases in DM digestion, gas accumulation, and total VFA production at initial pH of 6.2 and 6.7 were 2.8 and 4.4, 2.0 and 3.0, and 1.2 and 1.6 times those at initial pH of 5.7, respectively. The lag time to reach above 2% DM digestibility at low initial pH was taken more times (8 h) than at high and middle initial pH (4 h). Current data clearly indicate that ruminal pH is one of the important determinants of fiber digestion, which is modulated via the effect on bacterial attachment to fiber substrates.