• Asian-Australasian Journal of Animal Sciences
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• v.7 no.2
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• pp.165-169
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• 1994

Forty cross bred ($168\;{\pm}\;28\;kg$) bull calves were offered either untreated (US) or urea ammonia treated (TS) rice straw at five levels of feeding, namely; 60, 80, 100, 120 140% of ad libitum. Ad libitum level for each animal was estimated over a period of one month, which was followed by a preliminary period of 21 days and a collection period of 15 days. The maximum organic matter intake (OMI-kg/100 kg BW) were 2.08 and 3.35 for US and TS, respectively and urea treatment increased the maximum OMI by 61% than for US. In order to reach maximum intake the amount feed refusal should be 25% for US, but with TS maximum intake was not reached even when the amount of feed refused was 39% of that consumed. The OMD of US significantly decreased with increase in OMI, whereas with TS the decrease was not significant. The inability of animals to select between stems and leaves particularly in TS might be one of the reasons for its constant digestibility. Considering the substantial increases in intake and the negative effect on digestibility of US, further trials are warranted, as well as studies to determine the practical implications.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.1
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• pp.21-25
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• 1988

The rumen degradability of rice straw (untreated, urea-sprayed, urea-treated), grasses (Panicum maximum, Pennisetum clandestinum) and rice bran was compared. The mean in vivo organic matter digestibility of the untreated (US), urea-supplemented (SS) and urea-ammonia treated (TS) rice straw were 50.9, 53.9 and 57.4%, respectively. Rice bran contained extremely high levels of acid-insoluble ash (25.2% DM), and its OMD was 36.1%. Grasses had OMD values around 66%. Degradability measurements were performed with buffaloes using the nylon bag technique. The organic matter (OM) disappearance data were fitted to an model which was used to describe degradation pattern. The mean potentially degradable fraction for US, SS and TS was 61.5, 61.9 and 69.4%, respectively. Urea-ammonia treatment increased both the amount of OM degraded and the rate at which it was degraded in the rumen. Both grasses had similar values for degradable fraction (around 65%) and for rate constant for degradation (0.04). Rice bran contained high proportions of readily soluble material (23.9%), but the degradable OM fraction was only 13.2%. The low quality of rice bran is attributed to the contamination of rice hulls during processing.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.470-474
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• 2011

Rice straw is the main grain straw and is produced in large quantities every year in Korea. Pretreatment of lignocellulosic biomass using soaking process was carried out mild conditions at atmospheric pressure and temperature of $60^{\circ}C$. We found enzymatic hydrolysis condition of pretreated biomass. In case of a rice straw, compared with previous lignocellulosic biomass, we found that hydrolysis time was a shorter than others. Hydrolysis of SAA-treated rice straw has shown conversion rate was higher at $50^{\circ}C$. Hydrolysis was ended between 40~48 hour. Glucose conversion rate was higher when enzyme loading is 65 FPU/ml and 32 CbU/ml. When substrate concentration was 5%(w/v), it was that conversion rate was 83.8% after hydrolysis for 72 hr. In simultaneous saccharification and fermentation(SSF) experiment about SAA-treated rice straw, ethanol productive yield was highest from $40^{\circ}C$. The yield of that time was 33.05% from 48 hour.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.1
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• pp.1-6
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• 1990

The objective of this experiment was to compare the effect of pH-regulated alkaline hydrogen peroxide (AHP) treatment of rice straw with those of sodium hydroxide (NaOH) and anhydrous ammonia ($NH_3$) treatments on in sacco digestivility. Three non-lactating ruminally cannulated Holstein cows were fed a diet containing 90% forage and 10% concentrate on a dry matter (DM) basis. The AHP treatment significantly (p<0.05) reduced acid detergent lignin content of the straw, resulting in significant (p<0.05) increase of neutral detergent fiber (NDF), acid detergent fiber (ADF) and cellulose concentrations. Disappearance rates of DM and NDF of the straw significantly (p<0.05) increased at the incubation time of 24 h. On the other hand, those of ADF and cellulose were significantly (p<0.05) higher at the incubation time of 12 h than those of the others. The effective degradability of DM(EDDM), NDF(EDNDF), ADF(EDADF) and cellulose (EDCE) were determined using in sacco nylon bag technique on the basis of 0.05/h solid outflow rate. The greater differences (p<0.05) of EDDM, EDNDF, EDADF and EDCE were found between AHP treated straw and the others. In general, AHP treatment of the straw recorded higher digestion coefficients than untreated straw as well as NaOH and $NH_3$ treated straws. The results of this study demonstrate that AHP treatment can be used as a effective method for improving the nutritive value of rice straw for ruminants.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.4
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• pp.490-496
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• 2000

In vivo digestibility, nitrogen retention and microbial protein yield from diets of 100% ammonia treated rice straw (ARS) ($D_1$); 65% untreated rice straw (URS)+30% rice bran (RB)+5% SBM ($D_2$) and 85% ARS+15% RB ($D_3$) were determined using three Japanese Corriedale wethers in a $3{\times}3$ Latin Square Design. Results showed that DM consumption and organic matter digestibility were highest in $D_3$; but did not promote high protein digestibility, which RB+SBM had effected in URS based-diet. Dry matter intake and OM digestibility were the same for $D_1$ and $D_3$. Solubility of fiber bonds was increased by ammoniation, resulting in higher NDF digestibility. Nitrogen retention and microbial protein yield of rice bran supplemented groups was higher than ARS, but supplementation did not significantly increase efficiency of microbial protein synthesis from ARS which did occur when RB+SBM was added to untreated straw. The quality of ammoniated rice straw could be improved through RB supplementation because of its positive effects on DM digestibility, nitrogen retention and microbial protein yield. However, the addition of RB+SBM to URS resulted to more efficient N utilization.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.2
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• pp.75-83
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• 1990

An experiment was conducted with three ruminally and intestinally cannulated non-lactating cows of Finnish Ayrshire breed, to assess the ruminal degradation characteristics of oat (Avena sativa), rye (Secale cereale) and rice (Oryza sativa) straw by the nylon bag technique, and the subsequent post-ruminal degradation of their rumen-undegraded residues by using the mobile bag technique, respectively. The straw samples were untreated or treated with aqueous $NH_3$ or with urea solution in cold or hot water. The untreated straw samples were milled or chopped, and the treated straw samples were chopped. The constant values a, b, and c were computed according to the exponential equation, where a = intercept of degradation curve at time 0, b = potentially degradable material, c = rate of degradation of band (a+b) = maximum potential degradability (asymptote). It was found that nitrogen contents of chemically treated straw were markedly increased by both $NH_3$ and urea treatments. Milling the samples attributed to a remarkable loss at 0 h incubation time as compared to chopping of the respective samples. However, chemical treatment markedly improved the b value and the subsequent (a+b) values for dry matter, organic matter, neutral-detergent fiber, and acid-detergent fiber of the samples. Furthermore, temperature of the water used in the urea solutions was considered essential, since urea in hot water rather than in cold water seemed to enhance the overall degradability. The disappearance of rumen-incubated straw residues from the mobile bags ranged from 4.5 to 9.6% for the parameters measured. On average, the OM disappearance from bags was clearly higher for the residues of urea treated straw compared to those of ammonia treated straw, but the disappearance of NDF tended, however, to be higher on the ammonia treatment.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.12
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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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• v.7 no.3
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• pp.363-372
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• 1994

In two separate experiments with crossbred bulls (Sahiwal $\times$ indigenous) the effect of access to a urea-molasses lickblock (MOL-U-MIN) on straw diets was studied. The animals were given either untreated (US) or urea treated (TS) rice straw with or without lickblock supplementation. In experiment 1, individual dry matter intake (DMI) and dry matter digestibility (DMD) were measured, while in experiment 2 in addition to the above rumen (pH, ammonia, minerals) and blood (protein, minerals and haemotological) parameters were also measured. With both experiments urea treatment did not effect DMI, but lickblock supplementation significantly (p < 0.05) increased DMI. The DMD values obtained in both experiments for TS were significantly (p < 0.05) higher than for US, but lickblock supplementation did not effect the DMD of either US or TS fed animals. Both urea treatment (6.97 vs 6.93) and lickblock supplementation (6.98 vs 6.92) significantly (p < 0.001) reduced the rumen pH. Urea treatment and lickblock supplementation increased the rumcn $NH_3-N$ concentration (mg/100 ml) from 8.7 to 11.9 and 9.2 to 11.4, respectively. Both US and TS diets fed with or without lickblock increased the molar ratio of Na : K in saliva. Phosphorus content in blood plasma was significantly (p < 0.01) increased due to lickblock supplementation, whereas the Fc content in blood was significantly increased (p < 0.01) by urea treatment. Haemoglobin content in blood ranged from 11.3 to 11.7 g/dl, and was not influenced by urea treatment or lickblock supplementation. Lickblock significantly reduced the number of red blood cells, but increased the mean corpuscular volume. It is concluded that feeding urea treated straw with proper mineral supplementation could be a more economical alternative to lickblock supplementation.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1102-1108
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• 2000

An experiment was conducted as a Latin square design with four rumen fistulated local yellow cattle with a mean live weight of 230 kg. The treatments were: $(CLM_0)$ urea-treated rice straw ad libitum plus 1 kg cassava root meal (basal diet), $(CLM_{500})$ basal diet plus 500 g cassava leaf meal, $(CLM_{1000})$ basal diet plus 1,000 g cassava leaf meal, and $(CLM_{1500})$ basal diet plus 1,500 g cassava leaf meal. The results showed that there were differences in dry matter intake of urea-treated rice straw between treatments (p<0.05). The highest total dry matter intake was observed for treatment $CLM_{1500}$, with 2.62 kg DM/100 kg LWt/day, followed by treatments $CLM_{1000}$, $CLM_{500}$ and $CLM_0$, with 2.42, 2.00 and 1.86 kg DM/100 kg LWt/day, respectively. The ruminal ammonia concentration on treatment $CLM_{1500}$ was greater than on treatments $CLM_{1000}$, $CLM_{500}$ and $CLM_0$. There were non-significant differences in the ruminal pH among the treatments. The in sacco degradability of cassava leaf meal and cassava root meal was high, and on average 75 and 85% respectively of the DM had disappeared after 24 h of incubation. Degradation rate of urea treated rice straw was 64% after 72 h of incubation.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.682-689
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• 2015

A two-step process was investigated for pretreatment and fractionation of rice straw. The two-step fractionation process involves first, soaking rice straw in aqueous ammonia (SAA) in a batch reactor to recover lignin-rich hydrolysate. This is followed by a second-step treatment in a fixed-bed flow-through column reactor to recover xylo-oligomer-rich hydrolysate. The remaining glucan-rich solid cake is then subjected to an enzymatic process. In the first variant, SAA treatment in the first step dissolves lignin at moderate temperature (60 and $80^{\circ}C$), while in the second step, hot-water treatment is used for xylan removal at higher temperatures ($150{\sim}210^{\circ}C$). Under optimal conditions ($190^{\circ}C$ reaction temperature, 30 min reaction time, 5.0 ml/min flow rate, and 2.3 MPa reaction pressure), the SAA-hot-water fractionation removed 79.2% of the lignin and 63.4% of the xylan. In the second variant, SAA was followed by treatment with dilute sulfuric acid. With this process, optimal treatment conditions for effective fractionation of xylo-oligomer were found to be $80^{\circ}C$, 12 h reaction time, solid-to-liquid ratio of 1:12 in the first step; and 5.0 ml $H_2SO_4/min$, $170^{\circ}C$, and 2.3 MPa in the second step. After this two-step fractionation process, 85.4% lignin removal and 78.9% xylan removal (26.8% xylan recovery) were achieved. Use of the optimized second variant of the two-step fractionation process (SAA and $H_2SO_4$) resulted in enhanced enzymatic digestibility of the treated solid (99% glucan digestibility) with 15 FPU (filter paper unit) of CTec2 (cellulase)/g-glucan of enzyme loading, which was higher than 92% in the two-step fractionation process (SAA and hot-water).