• 한국유기농업학회지
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• 제23권2호
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• pp.323-334
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• 2015

본 연구는 수박 과실썩음병의 원인균인 A. avenae subsp. citrulli에 대해 항균활성을 갖는 친환경 유기농자재를 개발할 목적으로 오배자(S. chinensis)를 대상으로 수행되었다. 오배자를 MeOH로 추출하여 용매분획을 하였고, 용매분획 중에서 가장 강한 활성을 나타낸 hexane fraction을 column chromatography로 분리하여 활성이 강한 분획들을 GC-MS로 분석하였다. GC chromatogram 상의 주요 peak에 해당하는 mass spectrum과 Wiley library를 비교하여 profiling한 결과, 지방산인 myristic acid, palmitic acid와 3-n-pentadecylphenol이 주요 물질로 검출되었다. 이들 검출 화합물의 항균활성을 검정하기 위하여 표준품을 사용하여 bioassay한 결과, myristic acid와 3-n-pentadecylphenol 화합물이 강한 활성을 보였다. 따라서 오배자로부터 분리한 myristic acid와 3-n-pentadecylphenol 화합물이 항균 활성물질인 것을 구명하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권12호
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• pp.1689-1697
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• 2013

This study was designed to determine the effect of physical form and urea treatment of rice straw on rumen fermentation, microbial protein synthesis and nutrient digestibility. Four rumen-fistulated dairy steers were randomly assigned according to a 2 (2 factorial arrangement in a 4 (4 Latin square design to receive four dietary treatments. Factor A was roughage source: untreated rice straw (RS) and urea-treated (3%) rice straw (UTRS), and factor B was type of physical form of rice straw: long form rice straw (LFR) and chopped (4 cm) rice straw (CHR). The steers were offered the concentrate at 0.5% body weight (BW) /d and rice straw was fed ad libitum. DM intake and nutrient digestibility were increased (p<0.05) by urea treatment. Ruminal pH were decreased (p<0.05) in UTRS fed group, while ruminal ammonia nitrogen ($NH_3$-N) and blood urea nitrogen (BUN) were increased (p<0.01) by urea treatment. Total volatile fatty acid (VFA) concentrations increased (p<0.01) when steers were fed UTRS. Furthermore, VFA concentrations were not altered by treatments (p>0.05), except propionic acid (C3) was increased (p<0.05) in UTRS fed group. Nitrogen (N) balance was affected by urea treatment (p<0.05). Microbial protein synthesis (MCP) synthesis were greater by UTRS and CHR group (p<0.05). The efficiency of microbial N synthesis was greater for UTRS than for RS (p<0.05). From these results, it can be concluded that using the long form combined with urea treatment of rice straw improved feed intake, digestibility, rumen fermentation and efficiency of microbial N synthesis in crossbred dairy steers.

• Asian-Australasian Journal of Animal Sciences
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• 제11권4호
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• pp.351-362
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• 1998

Microbial growth efficiency in the rumen was studied in sheep given hourly, 31.25 g oaten chaff with either 0.31 and 0.88 g urea or 1.88 and 5.63 g casein (exp. 1) and 33.33 g oaten chaff with 1.04 casein or 0.3, 0.6 and 0.9 g urea or the mixture of the casein and urea (exp. 2). Concentrations of ruminal fluid ammonia increased with increasing nitrogenous supplements. Organic matter digestibility in sacco in the rumen was not different irrespective of N sources. Isoacids and valeric acid increased with increasing ingested casein but decreased with increasing urea intake. Peptide and amino acid pools in ruminal fluid increased with increasing ammonia concentrations (exp. 2) suggesting that proteolytic activity and transportation of peptides and amino acids across microbial membrane of rumen microbes may be regulated by the metabolite mechanism (intracellular amino acids and $NH_4{^+}$, respectively). Densities of total viable and cellulolytic bacteria in ruminal fluid increased with increasing ammonia levels but that of small Entodinia decreased. The density of fungal sporangia growth on oat leaf blades decreased with increasing ammonia concentrations but appeared to remain constant in the presence of casein. Efficiency of net microbial cell synthesis was 15-28% higher when ammonia concentrations increased from 100 to above 200 mg N/l regardless of N sources. In conclusion, supplementation of preformed protein had no effect on rumen digestion and microbial growth efficiency. This could not be accounted for its effect on ruminal fluid ammonia. Increased microbial growth efficiency with increasing ammonia levels may be due to a reduction in the turnover of microbial cells within the rumen.

• Asian-Australasian Journal of Animal Sciences
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• 제10권5호
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• pp.460-470
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• 1997

On an absolute straw diet, the effect of graded levels of green grass supplementation on intake, nutrient digestibility, rumen fermentation pattern and microbial N yield has been studied in cattle. Of the two trials conducted, 16 intact growing bulls of 304 kg weight and 32 months old, randomly allocated to four treatments in a completely randomized design in the 1st trial. While, in the, 2nd trial, four rumen cannulated local bulls of about 60 months old and 400 kg weight were used in a $4{\times}4$ Latin square design with four treatments in four periods. In both the trials, in addition to a mineral mixture, animals were supplemented with graded levels of naturally grown green grass of 0 kg (T1), 2 kg (T2), 4 kg (T3) or 6 kg (T4) to an ad libitum rice straw diet In the 1st trial, measurements were made on intake digestibility, growth rate, N balance and microbial N yield. While in the 2nd trial, in addition to the above parameters (except growth rate), rumen parameters were also studied. All levels of grass supplementation decreased the straw DM intake and increased the substitution rate. The rumen $NH_3-N$ concentration increased with the increase in grass level and ranges from 8-46 mg/l. The rumen pH and the rate and extent of DM degradability of straw were not affeceted by different rumen environments created by different levels of grass inclusion. At 48 h, straw DM degradability were 42, 44, 44 and 43% respectively for 0, 2, 4 and 6 kg grass supplementation daily. The whole gut digestibilities of DM, OM and ADF increased significantly (p < 0.05) only at 6 kg level daily. The microbial N yield was not affected by the levels of grass supplemented. The mean microbial N yield was 10 (SD 3.7) g/kg DOM apparently fermented in the rumen. The estimated minimum N loss and thus the maintenance requirement of tissue protein was 303 mg/kg $W^{0.75}/d$. All the animals lost live weight but 6 kg grass supplementation gave positive energy and N balances. Small amount of green grass supplementation is often recommended for optimization of rumen environment of a straw diet However, under the present experimental condition, no such beneficiary effect observed up to 6 kg (26% of DM intake) level of supplementation.

• Asian-Australasian Journal of Animal Sciences
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• 제11권3호
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• pp.209-216
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• 1998

The paper presented here is aimed at increasing knowledge on purine metabolism in ruminants and hence the quantification of microbial cells entering the small intestine from urinaη excretion of purine derivatives. Nucleic acid metabolisms of micro-organisms in the rumen, digestion and absorption of nucleic acids entering the intestines, metabolisms of absorbed and endogenous purines involving de novo synthesis of nucleic acids in the ruminants host, and the relationship between absorbed and excreted purines are reviewed. Principal concerns about an amount of purine derivatives excreted in urine in relation to a change in purine-N: total-N ratios in rumen microbes that leave the rumen are discussed. The use of urinary excretion of purine derivatives as an indicator of the amount of microbial biomass leaving the rumen has to be done with some caution since it may be impossible to get a representative sample of microbes entering the intestine and thus yield estimates are relative rather than absolute.

• 농약과학회지
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• 제10권1호
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• pp.56-65
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• 2006

작물 근권 토양으로부터 분리한 5,000여 길항 균주로부터 Erwinia 및 Pseudomonas등의 세균과 Trichoderma, Colletotrichum 등 곰팡이의 성장을 동시에 억제하는 Bacillus sp. N 32 균주를 선발 동정 하였다. 특히 Bacillus sp. N32 균주는 고추 탄저병균인 Colletotrichum gloeosporioides에 대하여 열에 저항성이 있는 단백질과 열에 민감한 단백질의 2종류의 항균 단백질을 동시에 생산함을 단백질 침전과 활성 검정을 통하여 확인하였다. 이 항균 단백질들을 FPLC를 이용한 gel filtration chromatography방법으로 분리한 후 SDS-PAGE와 bioautography로 항균력을 확인하였다. 또한 이 항균 단백질의 유전자들을 선발하기 위하여 기존의 알려진 그람양성 세균의 대표적인 열 저항성 항균 펩타이드 생합성 유전자 서열을 primer로 이용한 PCR 방법으로 fengycin의 생합성 유전자 단편을 분리하고 이 PCR 산물을 이용하여 Bacillus sp. N32 균주의 cosmid library로부터 fengycin의 생합성 유전자 cluster중 일부를 분리하여 염기서열을 분석하였다. 또한 열에 민감한 항균 단백질 생산 유전자는 이 항균 단백질을 SDS-PAGE 및 electroblotting으로 분리한 뒤 N-terminal 부위의 15개의 아미노산 서열을 분석하고 이를 DNA 염기배열로 치환한 다음 probe로 이용하여 ${\lambda}-ZAP$ library로부터 항균 단백질 생산 유전자가 포함된 다수의 clone을 선발하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권3호
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• pp.350-353
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• 2005

Effects of sucrose supplement on the pattern of VFA production and microbial protein synthesis in the rumen were examined in sheep consuming basal diet of grass silage (2.5 kg fresh wt/d) that was provided in 24 equal meals each day by an automatic feeder. Four mature wethers were allocated to four experimental treatments in a 4${\times}$4 Latin square design with periods lasting 14 days. The treatments were (1) the basal diet, (2) supplemented with 150 g sucrose and 7.0 g urea, (3) 300 g sucrose and 13 g urea, and (4) 450 g sucrose and 20 g urea given as a continuous intraruminal infusion for 24 h. All infusions were given in 2 litres of aqueous solution per day using a peristaltic pump. The effect of sucrose level on rumen mean pH was significantly linear (p<0.01). There were not significant differences in the concentration of ammonia-N, total VFA and the molar proportions of acetate, propionate and butyrate with the level of sucrose infusion. The molar proportions of isobutyric acid (p<0.05) and isovaleric acid (p<0.001) were significantly reduced when the infused amount of sucrose was increased. The flow of microbial N was linearly (p<0.001) increased with sucrose and urea level. High levels of readily fermentable carbohydrate in a ration reduced the efficiency of microbial protein synthesis in the rumen. It was demonstrated that of the individual fatty acids, only the molar proportion of isovalerate showed a significant negative correlation (R2=$0.3501^{**}$) with the amount of microbial N produced and a significant positive correlation (R2=$0.2735^{**}$) with the efficiency of microbial growth.

• Asian-Australasian Journal of Animal Sciences
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• 제10권4호
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• pp.364-370
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• 1997

Four local cattle were ($145{\pm}9.7kg$) used in a $4{\times}4$ Latin square design to study the effect of different levels of rumen degradable protein (RDP) in straw based ration on purine derivatives excretion and microbial N supply in cattle. The four rations were formulated at the same amount of energy but varying RDP approximately 50 (U0), 75 (U1), 100 (U2) and 150 (U3) percent levels of RDP requirement for maintenance. They were fed ranged from 101 to 304 g RDP/d. Apparent digestibility of all nutrients increased significantly (p < 0.01) in cattle fed ration U2 than other rations. Rumen $NH_3-N$ concentration increased from 43 to 130 mg/l in response of RDP intake. Purine derivatives excretion increased significantly (p < 0.01) with incremental level of 203 g RDP/d (U2) intake and positively correlated (r=0.69, p < 0.01, n=16) with amount of RDP intake. The rates of rumen microbial N supply were 16.8, 27.2, 39.1 and 32.9 g/d for rations U0, U1, U2 and U3 respectively. Efficiency of microbial N supply (EMNS) per kg of DOMR were 19.0, 25.3, 33.0, and 28.6 g and per MJ of ME. Intake were 0.62, 1.00, 1.44 and 1.21 g for U0, U1, U2 and U3 respectively and highest results were obtained in cattle fed U2 ration. Results of this study suggest that PD excretion and EMNS were increased as incremental level of RDP intake (U2) in local cattle.

• Asian-Australasian Journal of Animal Sciences
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• 제30권2호
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• pp.181-186
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• 2017

Objective: Leucaena leucocephala (Leucaena) is a perennial tropical legume that can be directly grazed or harvested and offered to ruminants as hay, silage, or fresh. However, Leucaena contain phenolic compounds, which are considered anti-nutritional factors as these may reduce intake, digestibility and thus animal performance. Therefore, the objective of this experiment was to determine effects of Leucaena silage (LS) feeding levels on rumen microbial populations, N-balance and microbial protein synthesis in dairy steers. Methods: Four, rumen fistulated dairy steers with initial weight of $167{\pm}12kg$ were randomly assigned to receive dietary treatments according to a $4{\times}4$ Latin square design. Treatments were as followings: T1 = untreated rice straw (RS; Control), T2 = 70% RS+30% LS, T3 = 40% RS+60% LS, and T4 = 100% LS. Dairy steers were fed rice straw and LS ad libitum and supplemented with concentrate at 0.2% of body weight/d. Results: Results revealed that the rumen microbial population, especially cellulolytic, proteolytic bacteria and fungal zoospores were enhanced in steers that received 60% of LS (p<0.05), whereas the amylolytic bacteria population was not affected by treatments (p>0.05). Protozoal population was linearly decreased with increasing level of LS (p<0.05). Moreover, N-balance and microbial protein synthesis were enhanced by LS feeding (p<0.05) and were the highest in 60% LS group. Conclusion: Based on this study, it could be concluded that replacement of RS with 60% LS significantly improved microbial population and microbial protein synthesis in diary steers.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1137-1142
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• 2003

In a balanced incomplete block design, two dry Holstein cows were used to investigate the effect of $\beta$ 1-4 galactooligosaccharides (GOS) supplementation on nitrogen (N) utilization, rumen fermentation and microbial N supply in the rumen. During the experiment, cows were fed four diets: orchardgrass (Dactylis glomerata L.) silage (OS), OS with GOS supplementation (OSG), OS mixed with alfalfa (Medicago sativa L.) silage (MS) and MS with GOS supplementation (MSG). GOS was supplemented at 2% of dry matter intake. Diets were fed at maintenance level of protein and energy. Results showed that N digestion was affected by silage and interaction of silage and GOS supplementation. Cows fed OSG had the highest N digested (p<0.05) followed by MS, OS and MSG. Supplementation of GOS to OS or MS diets tended to improve N utilization through reducing the N losses on dairy cows. There was no effect of GOS supplementation on rumen fermentation parameters (i.e. pH, $NH_3$-N and total VFA) at 1 h and 6 h after feeding. Compared to cows fed MS, cows fed OS silage had higher (p<0.05) allantoin excretion (80.8 vs. 67.1 mmol/d) and higher (p<0.05) total purine derivatives excretion (92.9 vs. 78.5 mmol/d). The microbial N supply in cows fed OSG was higher (p<0.05) than those fed OS, MS and MSG.