Sorghum Stover Research Articles

Effects of Chopping on Utilization of Sorghum Stover by Nubian Goats

Effects of chopping sorghum stover (Tabat variety) on Dry Matter Intake (DMI), apparent digestibility and body weight changes in Nubian goats were studied in the Gezira, Sudan. The chemical composition of the stover (%) was 96.78±0.83, 1.43±0.02, 4.65±0.39, 42.98±0.01, 9.99±0.89 and 40.96±1.24 for DM, EE, CP, CF, ash and NFE, respectively. Dry matter intake on different basis was higher for the chopped stover and the effect was significant (p<0.05) as g/d (606 for the long and 687 for the short). Chopping decreased losses in BW, but not significantly. It was (kg/week) 0.616 for the long and 0.366 for the short. Chopping increased nutrients apparent digestibilities and the effect was significant (p<0.05), except for CF and EE. They were 55.20, 59.11, 18.60 and 41.78 and 67.89 for DM, OM, CP, EE and CF, respectively for the long and 65.87, 68.15, 45.28, 53.90 and 72.47, respectively for the short.

Cattle Gain and Crop Yield for a Dryland Wheat‐Sorghum‐Fallow Rotation

Increasing pumping costs and declining well capacities in the U.S. Southern High Plains have led to greater reliance on less productive and inherently riskier dryland cropping systems. Dryland wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] are typically grown in a 3‐yr wheat‐sorghum‐fallow (WSF) rotation that may be intensified by integrating cattle (Bos taurus) grazing. Suitability of grazing dryland crops in the WSF rotation has not been evaluated. Our objectives were to quantify (i) cattle gain during limited grazing of dryland wheat and sorghum stover, and (ii) grazing effects on the growth and yield of the grazed wheat and subsequent sorghum crop. We established, concurrently, all WSF rotation phases in duplicate ungrazed and grazed plots in three replicated paddocks on a gently sloping Pullman silty clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) at the USDA‐ARS, Conservation and Production Research Laboratory, Bushland, TX (35°11′ N, 102°5′ W). Cattle gain, fallow soil water storage, and the growth and yield of wheat and subsequent grain sorghum were compared from 2000 to 2007 within a randomized complete block. Dryland wheat was grazed an average of 31 d during 7 of 8 test years by cattle stocked at 1.7 Mg ha−1 and produced a mean gain of 123 kg ha−1. Wheat grain yield averaged 1.72 Mg ha−1 without grazing and was not different from the 1.57 Mg ha−1 grain yield with grazing. Grazing decreased wheat straw yield, but subsequent soil water storage was unaffected. Sorghum grain yields of 2.26 Mg ha−1 in ungrazed plots were not different from grazed plots averaging 2.20 Mg ha−1. Overall productivity of the WSF cropping system was increased using limited grazing of dryland wheat forage and sorghum stover with no significant reduction in wheat or sorghum grain yields.

Comparison of cotton seed cake and poultry litter as protein sources in the diets of growing wadara cattle fed basal diet of sorghum stover in semi arid region of Nigeria

Comparison of cotton seed cake and poultry litter as protein sources in the diets of growing wadara cattle fed basal diet of sorghum stover in semi arid region of Nigeria

Effect of supplementing different levels of leftover of khat (Catha edulis) to sorghum stover on nutrient intake and digestibility by goats

AbstractSupplementation with the leftover of khat (Catha edulis) of sorghum stover at 45–60% dry matter improved the intake and apparent digestibility of the dry matter and nutrients of the total diet by goats. Copyright © 2006 John Wiley &amp; Sons, Ltd

Acceptability and growth of goats fed with khat (Catha edulis) leftover as a sole diet and supplement

AbstractLeftover of khat (Catha edulis) fed to goats as a sole diet or supplement improved body weight gain and did not affect the haematological parameters. Supplementation of sorghum stover by up to 45% of khat leftover increased intakes of dry matter and nutrients, body weight gain and feed conversion efficiency of goats. Copyright © 2006 John Wiley &amp; Sons, Ltd

Effect of Positioning of Feed Samples in Two Segments of the Rumen on In-situ Degradability of Feed Stuffs

The effect of positioning of Sorghum Stover and groundnut haulms at dorsal and ventral segments of rumen was investigated using Nylon bags for 4, 24 and 48 hours incubation in the rumen of two cannulated bulls. The 24 hour dry matter (DM) disappearance values were 60.05 (dorsal segment), 58.93 (ventral segments) for the groundnut haulm and 14.65 (dorsal segment), 15.75 (ventral segments) for Sorghum Stover respectively, with the following corresponding rates of degradability (C value) 0.010, 0.009, 0.005 and 0.004 respectively. The results showed no significant effect of positioning in the rumen. Expectedly the groundnut haulms were however degraded more than the Sorghum Stover, making the dry matter from the latter more available to the host animal than those of the former. The difference in the rate of degradation between groundnut haulm and sorghum stover must have rested on the degree of exposure of the degradable samples to the various rumen microbial species rather than that of rumen positioning of those feedstuff samples

Long-term soil management effects on crop yields and soil quality in a dryland Alfisol

A long-term experiment was conducted with the objective of selecting the appropriate land management treatments and to identify the key indicators of soil quality for dryland semi-arid tropical Alfisols. The experiment was conducted using a strip split–split plot design on an Alfisol (Typic Haplustalf) in southern India under sorghum ( Sorghum vulgare (L))-castor ( Ricinus communis (L)) bean rotation. The strip constituted two tillage treatments: conventional tillage (CT) and minimum tillage (MT); main plots were three residues treatments: sorghum stover (SS), gliricidia loppings (GL), ‘no’ residue (NR) and sub plots were four nitrogen levels: 0 (N 0), 30 (N 30), 60 (N 60), and 90 kg ha −1 (N 90). Soil samples were collected after the sixth and seventh year of experimentation and were analyzed for physical, chemical and biological parameters. Sustainable yield index (SYI) based on long-term yield data and soil quality index (SQI) using principal component analysis (PCA) and linear scoring functions were calculated. Application of gliricidia loppings proved superior to sorghum stover and no residue treatments in maintaining higher SQI values. Further, increasing N levels also helped in maintaining higher SQI. Among the 24 treatments, the SQI ranged from 0.90 to 1.27. The highest SQI was obtained in CTGLN 90 (1.27) followed by CTGLN 60 (1.19) and MTSSN 90 (1.18), while the lowest was under MTNRN 30 (0.90) followed by MTNRN 0 (0.94), indicating relatively less aggradative effects. The application of 90 kg N ha −1 under minimum tillage even without applying any residue (MTNRN 90) proved quite effective in maintaining soil quality index as high as 1.10. The key indicators, which contributed considerably towards SQI, were available N, K, S, microbial biomass carbon (MBC) and hydraulic conductivity (HC). On average, the order of relative contribution of these indicators towards SQI was: available N (32%), MBC (31%), available K (17%), HC (16%), and S (4%). Among the various treatments, CTGLN 90 not only had the highest SQI, but also the most promising from the viewpoint of sustainability, maintaining higher average yield levels under sorghum–castor rotation. From the view point of SYI, CT approach remained superior to MT. To maintain the yield as well as soil quality in Alfisols, primary tillage along with organic residue and nitrogen application are needed.

Measuring the potential impacts of improved food-feed crops: methods for ex ante assessment

The recent increased emphasis on impact assessment is due in part to the rapidly changing nature of funding for agricultural research and the shifts that have occurred in what is expected of the agricultural research community. The reasons for doing impact assessment are relatively clear: ex post studies can determine the impact of past investment in research on target beneficiaries and are a way to learn some of the lessons of the past. Ex ante studies can provide information to assist in the allocation of scarce research resources to activities that best match donors’ development objectives. In practice, impact assessment is often contentious and almost always difficult, particularly when livestock are involved. In this paper, we outline methods that can be used in ex ante impact assessment, and illustrate some of these in relation to three recent studies on improved food-feed crops in different places: improving the quality of millet and sorghum stover in India, using dual-purpose cowpea in West Africa, and alternatives for utilizing maize stover in the mixed systems of East and Southern Africa. Such impact assessments are neither cheap nor quick, and the methods that are most appropriate in any situation will depend not only on the resources and expertise available but most importantly on the exact nature of the questions being asked and the end-users of the results. Much remains to be done to maximize the utility of such assessments, particularly in the areas of quantitative model development, rapid qualitative method development, more effective integration of biophysical and socio-cultural indicators and approaches, and provision of baseline data against which to measure progress. Research resource allocation may well retain its somewhat haphazard nature in the future, but given the challenges facing agriculture in developing countries, a mechanism for attempting to ensure that research and extension really do contribute to widely held development goals has to be based on more than trial and error.

Improving the production and utilization of cowpea as food and fodder

Cowpea ( Vigna unguiculata (L.) Walp.) is an important food legume and an integral part of traditional cropping systems in the semi-arid regions of the tropics. The estimated worldwide area under cowpea is about 14 million ha of which West Africa alone accounts for about 9.3 million ha with annual production of about 2.9 Mt. Cowpea grains are consumed as food and the haulms are fed to livestock as a nutritious fodder. Farmers often grow a short-duration spreading variety for grain and a long-duration spreading variety for fodder, but the grain and fodder yields are poor due to low yield potential of the spreading varieties and also due to early cessation of rains. Therefore, IITA in collaboration with ILRI has initiated a systematic programme to develop medium-maturing, semi-erect, dual-purpose varieties with higher grain and fodder yields and with enhanced fodder quality. By crossing the late, traditional spreading varieties with improved early, semi-erect varieties, a semi-erect group of medium-maturing, dual-purpose varieties has been developed which yield over 1.5 t ha −1 grain and 2.5 t ha −1 haulms. Despite the high grain and fodder yields, the haulms of improved dual-purpose varieties have similar crude protein content (17–18%) and dry matter digestibility (64–71%) compared to the local varieties. Controlled sheep feeding experiments have shown an average live weight gain of about 80 g per animal per day with 200–400 g per day of cowpea haulms as a supplement to a basal diet of sorghum stover. This was 100% higher than the average live weight gain of animals fed sorghum fodder alone. These results indicate that improved dual-purpose varieties can play an important role in enhancing crop–livestock integration in West Africa.

Improving the production and utilization of sorghum and pearl millet as livestock feed: progress towards dual-purpose genotypes

The overall objective of this work was to investigate variation in grain yield (GY), stover yield (SY), fodder quality of stover and their association in sorghum and pearl millet. These relationships were investigated in India in 12 genotypes of sorghum and six genotypes of pearl millet grown under high fertilizer (HF) and low fertilizer (LF) application. Fodder quality of stover was assessed by digestibility and intake measurements in bulls. In sorghum, highly significant genotype-dependent variation was found for GY, SY and fodder value of stover regardless of level of fertilizer application. GY and fodder quality of stover were not inversely related and the genotype with the highest GY, for example, had also the best fodder quality in the stover. High GY and high fodder quality in sorghum stover seem to be compatible traits. In pearl millet, genotypic variation in GY and SY and quality was expressed under HF but not under LF application. No consistent significant genotypic differences were found for fodder quality measurements in pearl millet except for cell wall digestibility. Digestible organic matter intake (DOMI) when bulls were fed to appetite was considered the crucial determinant of stover quality in sorghum and pearl millet. Live weight changes in bulls estimated by DOMI varied genotype-dependently from −140 to +100 g per day in 300 kg bulls. However, this paper argues that genotypes promoting high DOMI are only suitable for farmers with sufficient amounts of stover to allow the feeding of animals to appetite. Farmers with restricted amounts of stover are better served by genotypes that promote high digestibility under restricted feed intake.

Nutritional status of Pleurotus spp. grown on various agro-wastes

Three species of Pleurotus, P. sajor-caju, P. platypus and P. citrinopileatus were cultivated on different agro-wastes: cotton stalk, coir fibre, sorghum stover and mixtures of these wastes. The primordial initiation day was observed between the 21st and 30th day after spawning. The yield was maximum on cotton stalks in P. sajor-caju and P. citrinopileatus. P. platypus yielded the maximum on sorghum stover. The biological efficiency, nutrient composition, energy value and energy recovery of the fruit bodies were estimated.

Chlamydospores of Fusarium Oxysporum Schlecht f.sp. orthoceras (Appel & Wollenw.) Bilai as Inoculum for Wheat-flour—Kaolin Granules to be Used for the Biological Control of Orobanche cumana Wallr.

The formation of chlamydospores of Fusarium oxysporum Schlecht. f.sp. orthoceras (Appel & Wollenw.) Bilai, a potential mycoherbicide for the parasitic weed Orobanche cumana Wallr., was optimised regarding the composition of the liquid growth medium. After 16 days of incubation, highest chlamydospore counts (approximately 2 × 107ml−1) were determined in an aqueous solution amended with 1.5% (w/v) finely ground sorghum stover and 30% (v/v) wheat-based stillage, a liquid by-product of ethanol production. The produced fungal biomass retained viability after being air-dried and stored. Granules made from wheat-flour and kaolin (Pesta) containing microconidia or air-dried chlamydospore-rich biomass were prepared and showed high efficacy in controlling O. cumana in the greenhouse. No differences in efficacy were observed between the different types of inoculum used.

Subsoil compaction effects on crops in Punjab, Pakistan:

Crop yields can be reduced by soil compaction due to increased resistance to root growth, and decrease in water and nutrient use efficiencies. A field experiment was conducted during 1997–1998 and 1998–1999 on a sandy clay loam (fine-loamy, mixed, hyperthermic Typic Haplargids, USDA; Luvic Yermosol, FAO) to study subsoil compaction effects on root growth, nutrient uptake and chemical composition of wheat ( Triticum aestivum L.) and sorghum ( Sorghum bicolor L. Moench). Soil compaction was artificially created once at the start of the study. The 0.00–0.15 m soil was manually removed with a spade. The exposed layer was compacted with a mechanical compactor from 1.65 Mg m −3 (control plot) to a bulk density of 1.93 Mg m −3 (compacted plot). The topsoil was then again replaced above the compacted subsoil and levelled. Both compacted and control plots were hoed manually and levelled. Root length density, measured at flowering stage, decreased markedly with compaction during 1997–1998 but there was little effect during 1998–1999. The reduction in nutrient uptake by wheat due to compaction of the subsoil was 12–35% for N, 17–27% for P and up to 24% for K. The reduction in nutrient uptake in sorghum due to subsoil compaction was 23% for N, 16% for P, and 12% for K. Subsoil compaction increased N content in wheat grains in 1997–1998, but there was no effect on P and K contents of grains and N and P content of wheat straw or sorghum stover. During 1997–1998, K content of wheat straw was statistically higher in control treatment compared with compacted treatment. In 1998, P-content of sorghum leaves was higher in compacted treatment than uncompacted control. Root length density of wheat below 0.15 m depth was significantly reduced and was significantly and negatively correlated with soil bulk density. Therefore, appropriate measures such as periodic chiselling, controlled traffic, conservation tillage, and incorporating of crops with deep tap root system in rotation cycle is necessary to minimize the risks of subsoil compaction.

Allelopathy of Sorghum on Wheat under Several Tillage Systems

Allelopathy by grain sorghum [Sorghum bicolor (L.) Moench] frequently harms wheat (Triticum aestivum L.) when the crops are grown in rotation. Responses of seven wheat cultivars to different methods of tilling sorghum stover were investigated to determine if the problem might be remedied by genetic resistance or improved management of the stover. Field trials on Kahola silt loam soil (fine‐silty, mixed mesic Cumulic Hapludolls) compared effects of fallow, tilled sorghum stover, and no‐till sorghum stover during the first season and the same treatments plus no‐till millet [Pennisetum glaucum (L.) R. Br.] stover the second season. The seven wheat cultivars were planted after the sorghum and millet were harvested and tilled, and their emergence, stand density, and yield components were measured. Tilled sorghum residue often delayed development of the following wheat crop but did not affect grain yields, probably because allelopathic compounds degraded in the soil. No‐till sorghum stover had little effect on stand establishment but frequently reduced grain yields of wheat, possibly because allelopathic compounds leached slowly. Wheat grain yields (means of all seven cultivars) were 3.3, 2.8, and 2.3 Mg/ha in fallow, tilled sorghum residue, and no‐till sorghum residue, respectively, during 2 yr and 3.1 Mg/ha in no‐till millet residue in the second year. Selection of resistant wheat cultivars is probably impractical, because differences were small and inconsistent. However, if erosion of soil is not a concern, allelopathy might be reduced by prompt tillage and other practices that promote rapid decomposition of sorghum stover.

Cowpea ( Vigna unguiculata L. Walp) and groundnut ( Arachys hypogea L.) haulms as supplements to sorghum ( Sorghum bicolor L. Moench) stover: intake, digestibility and optimum feeding levels

Two feeding trials were conducted to study the combined effects of (i) varying degrees of selective consumption and (ii) supplementation with cowpea (Trail 1) or groundnut haulms (Trial 2), on intake of organic matter (IOM) from sorghum stover, and total intake of digestible organic matter (IDOM). In both trials, 36 rams were allocated to 36 different treatments: six levels of feeding sorghum stover (25, 40, 60, 90, 120 and 160 g organic matter (OM) kg −0.75 per day) combined with six levels of supplementation (0, 5, 12.5, 20, 40, and 60 g OM kg −0.75 per day). Each diet was offered for a 21 day period; intake and digestibility were recorded during the last 9 days. Non-linear regression models were used to describe the combined effects of varying amounts of stover ( x) and supplements ( s) offered. All animals ate the full amount of supplement offered, but not the sorghum stover. For animals without supplement, maximum intake ( m) of stover (i.e. IOM at high levels of x) was estimated at 50.7 g kg −0.75 per day in Trial 1 and 45.7 g kg −0.75 per day in Trial 2. In both trials, m decreased linearly with s at the rate 0.4 g g −1. Also, the shape of the curve relating intake of stover to x was affected by level of supplementation. Digestibility of whole stover (0.47 in Trial 1; 0.40 in Trial 2) was much lower than that of cowpea haulms (0.70) and groundnut haulms (0.62), but in both trials animals selected material of higher digestibility when excess stover was offered. Thus, the negative effect of supplementation on intake of stover was partly compensated by higher digestibility of consumed stover. For rations without cowpea in Trial 1, the maintenance level of IDOM was reached by offering 61 g sorghum OM (kg −0.75 per day) of which 47 g was consumed. With the same amount of offered sorghum 9, 18, 28, 38 and 48 g cowpea OM were needed to attain intake levels equivalent to 1.2, 1.4, 1.6, 1.8 and 2.0 times maintenance, respectively. In the trial with groundnut, maintenance was not reached with sorghum alone and larger amounts of supplement were required for the levels of intake mentioned above. Iso-production curves describing which amounts of stover and supplement gave the same IDOM, were not linear with constant slope corresponding to the comparative digestibility of whole stover and supplements, but strongly curved. Such curves can be used to derive optimum combinations of stover and higher quality feeds, depending on feed prices, desired production level and taking into account the effects of selective consumption. With prices of cowpea and groundnut haulms 4 times higher than that of stover, the results of Trial 1 indicate that least cost rations for feeding at 1.2 M (maintenance) would consist of 72 g sorghum OM (kg −0.75 per day) combined with 7 g cowpea haulms. For feeding at 1.6 M this would be 70+26 g , and at 2 M, 54+50 g . Similarly, with the feeds used in Trial 2, optimum combinations of sorghum stover and groundnut haulms for the same levels of feeding would be 58+24, 51+47, and 11+78 g OM kg −0.75 per day .

Effect of selective consumption on voluntary intake and digestibility of sorghum (Sorghum bicolor L. Moench) stover, cowpea (Vigna unguiculata L. Walp.) and groundnut (Arachis hypogaea L.) haulms by sheep

Three experiments with 12 animals each, were conducted to measure the effect of selective consumption on intake of organic matter (IOM), crude protein (CP) content and digestibility of ingested organic matter (DOM), and intake of digestible organic matter (IDOM) of sorghum (Sorghum bicolor L. Moench), stover (SS), cowpea (Vigna unguiculata Walp.) (CH) haulms and groundnut (Arachis hypogaea L.) haulms (GH) by sheep. On organic matter (OM) basis, SS contained 70.6% stems, 15.5% leaf sheaths, 6.5% leaf blades, 6.0% leaf central nerves and 1.4% ears; CH contained 64.2% stems and 35.8% leaves, and GH 50.1% stems and 49.9% leaves. Forages were not chopped and a wide range of feeding levels (amount of offered organic matter, OOM) was applied. The lowest and highest OOM (g kg ˇ0.75 per day) were: 30‐110 for SS, 37‐189 for CH and 30‐194 for GH. Maximum IOM values (estimated by non-linear regression analysis) were 47.3, 85.9 and 81.6 g kg ˇ0.75 per day for SS, CH and GH, respectively. Selective consumption of leaves caused significant increases in the CP content of ingested OM for CH and GH, and increased DOM for SS and CH. The amount of digestible OM for production (IDOM — maintenance requirements) per unit of feed OM offered (value for animal production (VAP)) was used as the criterion for optimum feeding levels. For CH and GH, the maximum value (VAPmax) (0.32 and 0.26, respectively) was reached at feeding levels of 96 and 91 g OM kg ˇ0.75 per day, respectively. At these levels of OOM, 80 and 84% of the offered OM was eaten. Corresponding IDOM values were 54.3 and 48.0 g kg ˇ0.75 per day. In the case of SS, a very high feeding level

Mesure de la valeur alimentaire de fourrages et de sous-produits utilisés dans l'alimentation des petits ruminants

Les valeurs alimentaires de six fourrages disponibles localement ont été déterminées lors de deux essais de digestibilité à l'aide des moutons Toronké. Le premier essai a porté sur la paille de brousse (PB) et la paille de sorgho (PS). Les ingestions de PB et de PS ont respectivement été de 62 et 51 g de matière sèche (MS) par kilogramme P0,75 . Les valeurs énergétiques ont été de 0,71 et 0,60 UFL/kg de MS respectivement pour la PB et les PS. Les teneurs en matières azotées digestibles (MAD) ont été de 3 et 1 g/kg de MS respectivement pour la PB et la PS. Si les valeurs énergétiques ont été assez bonnes, les valeurs azotées ont été très faibles ; elles représentent une contrainte majeure des productions animales au Mali. Le deuxième essai a porté sur la fane d'arachide (FA), la fane de dolique (FID), les pailles de maïs (PM) et de mil (PL). Les ingestions ont été de 97, 99, 40 et 35 g MS/kg P0,75 respectivement pour les FA, FD, PM et PL. Les digestibilités des nutriments ont été plus élevées dans les fanes que dans les pailles, excepté celle de la cellulose brute. Les teneurs en MAD des pailles ont été négatives. Celles des fanes ont été de 67 et 58 g/kg MS respectivement pour la FA et la FD. Les valeurs énergétiques des aliments ont été de 0,76, 0,63, 0,50 et 0,42 UFL/kg de MS respectivement pour la FA, la FD, la PM et la PL. Les pailles ont eu une valeur énergétique peu élevée et une valeur azotée nulle. Les fanes riches en matières azotées totales, de digestibilité et d'ingestibilité élevées, peuvent contribuer à l'amélioration de la valeur alimentaire des pailles de céréales par une supplémentation appropriée. P0,75

Manejo de colheita e espaçamento da palma-forrageira, em consórcio com sorgo granífero, no Agreste de Pernambuco

Este trabalho foi realizado na zona semi-árida de Pernambuco e teve como objetivo investigar o efeito de espaçamento, e a freqüência e intensidade de colheitas da palma-forrageira (Opuntia ficus-indica Mill.) consorciada com sorgo granífero (Sorghum bicolor (L.) Moench). O delineamento experimental foi o de blocos ao acaso em parcelas subdivididas, sendo os espaçamentos alocados nas parcelas principais, e as freqüências e intensidades de colheitas, nas subparcelas. Os resultados são de um período de 12 anos, e as produções de matéria seca de palma, de grãos e restolhos de sorgo foram: 5,23, 1,65 e 2,07; 4,51, 1,30 e 2,10; 2,75, 1,97 e 3,51 t/ha/ano, em espaçamentos de 2,0 m x 1,0 m; 3,0 m x 1,0 m x 0,50 m e 7,0 m x 1,0 m x 0,50 m, respectivamente. A produção de matéria seca foi diferente entre as freqüências de corte, quando foram conservados os artículos primários: 4,08 t/ha/ano na freqüência de quatro anos, e de 3,43 t/ha/ano na freqüência de dois anos. A produção de palma aumentou com o período de crescimento da planta, nas duas intensidades de corte estudadas. A composição química dos artículos de palma e dos restolhos de sorgo foi pouco afetada pelos tratamentos.

Fermentative production of acetic acid from various pure and natural cellulosic materials by Clostridium lentocellum SG6

Clostridium lentocellum SG6 fermented various pure crystalline cellulosic materials efficiently with maximum acetic acid yield (gram acetic acid/gram substrate) of 0.67, at low substrate (8 g l−1) concentration. The strain grew poorly on crude biopolymers but fermented them easily after alkali treatment, when grown with 8 g substrate l−1 concentration of alkali-extracted cotton straw (AECS), paddy straw (AEPS) and sorghum stover (AESS) etc. The acetic acid to substrate (A/S) ratios were similar to those obtained with pure cellulosic materials. An increase in substrate concentration led to a decreased A/S ratio and a decreased percentage of substrate degraded. At high substrate concentration of 75 g filter paper l−1, the strain SG6 converted 63.2 g filter paper into 31.28 g acetic acid l−1. At 100 g l−1 concentrations, AECS and AEPS served as the best substrates for acetic acid production when compared with other biopolymers. A maximum amount of 30.98 and 30.86 g acetic acid was produced from 70.6 g AEPS and 70.1 g AESS l−1 of medium by strain SG6, respectively. Acetic acid production of 0.67 g g−1 pure cellulose (Whatman No. 1 filter paper), 0.63 g g−1 of alkali-treated cotton straw (AECS) are the highest among the cellulolytic bacteria reported so far in mono culture fermentations with pure and native cellulosic materials.

Thein vitro gas coupled with ammonia measurement for evaluation of nitrogen degradability in low quality roughages using incubation medium of different buffering capacity

Owing to low N content in low quality roughages, the estimation of in vitro rumen degradable nitrogen (IVRDN) by the method of Raab et al (Br J Nutr 1983 50 569–582) is expected to have a high standard deviation. Incubation of larger amounts of sample will increase the amount of N in the system and decrease analytical errors in the determination of IVRDN. The increase in the amount of sample necessitated an increase in the amount of buffer in the medium. In this study the effect of 30 ml (as is in original method) and 40 ml buffered rumen fluid (containing double the amount of hydrogen carbonate buffer as in the original method) on rumen degradation of N from low quality roughages was evaluated. N degradability of seven cereal straws (barley, millet, oat, rice, sorghum, triticale and wheat) and one grass hay was calculated from the linear regressions of NH3-N concentration vs in vitro gas production. The strength of association (r2) for gas production and NH3-N concentration between 30 and 40 ml system was significantly (P<0·05) different for grass hay and rice straw but not significant for other feeds. Using both systems, the IVRDN for triticale straw was virtually nil, and for others the values obtained using 40 ml system were either similar (oat straw, rice straw, sorghum stover and wheat straw) or higher (barley straw, grass hay and millet stover) than those obtained using 30 ml system. Although no significant difference was found in the standard deviation by increasing the amount of sample, the larger sample has an advantage in that it allows concomitant determination of in vitro apparent and true digestibility. © 1998 SCI.