Fermentation Characteristics (fermentation + characteristic)

Distribution by Scientific Domains


Selected Abstracts


Fermentation characteristics and aerobic stability of grass silage inoculated with Lactobacillus buchneri, with or without homofermentative lactic acid bacteria

GRASS & FORAGE SCIENCE, Issue 4 2001
F. Driehuis
Aerobic spoilage by yeasts and moulds is a major cause of reduced nutritional value of silage and increases the risk of potential pathogenic microorganisms. Recent studies have shown that inoculation with Lactobacillus buchneri inhibits yeast growth and reduces the susceptibility to aerobic spoilage of various ensiled forages. The aim of this study was to determine whether these effects are retained when L. buchneri is added in combination with homofermentative lactic acid bacteria. In three experiments, silages were produced from perennial ryegrass [240,421 g kg,1 dry matter (DM)] inoculated with L. buchneri or L. buchneri plus a mixture of Pediococcus pentosaceus and Lactobacillus plantarum (inoculant PL). Uninoculated silage and silage inoculated with PL alone served as controls. Silages were examined for pH and DM loss in the course of ensilage and chemical and microbiological composition and aerobic stability after 3,4 months. L. buchneri plus PL and PL alone increased the initial rate of pH decline. L. buchneri alone and L. buchneri plus PL enhanced aerobic stability and, in general, reduced yeast and mould counts. In addition, these inoculants increased the final pH and DM loss and the concentrations of acetic acid and 1,2-propanediol (or propionic acid and 1-propanol instead of 1,2-propanediol), and decreased the concentration of lactic acid. The effects of L. buchneri on fermentation products increased with decreasing DM content. In silages of less than 270 g kg,1 DM, L. buchneri increased the ammonia-N concentration. It is suggested that this was associated with the relatively high final pH resulting from the high metabolic activity of L. buchneri in these silages. [source]


Fermentation characteristics and microbial growth promoted by diets including two-phase olive cake in continuous fermenters

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1 2008
A. Moumen
Summary Two-phase olive cake (2POC) is the by-product obtained from the so called ,two-phase' procedure to extract olive oil by mechanical methods. After the mechanical extraction the 2POC is dried and most of the remaining oil extracted by chemical means. The production of the crude by-product may reach more than 4 millions t/year in Spain (MAPA, 2003), most of it in areas (Southeast) with shortage of pastures and conventional feeds for ruminants. Six continuous fermenters, inoculated with ruminal liquor from wethers or goats, were fed lucerne hay (LH); LH plus a concentrate including dried two-phase olive cake (LHCO) and; diet LHCO added with polyethylene glycol (LHCOP). The highest pH values and ammonia N (NH3 -N) output were found in fermenters fed diet LH (6.19 and 6.35 for pH, and 53.7 and 68.9 mg NH3N/day, respectively, in fermentes inoculated with rumen liquor from sheep and goats) without differences due to the inoculum origin. The digestibility of carbohydrates (CHO) was affected (p < 0.001) by inoculum (67.0 and 58.8%, respectively, for goats and wethers) the lowest values being for diet LHCO (53.2 and 57.0% with inoculum from wethers and goats, respectively). The main volatile fatty acid (VFA) was acetic acid with higher (p < 0.01) values in fermenters with inoculum from goats than from wethers (80.2 and 63.0 mmol/day respectively). The efficiency of bacterial protein synthesis (EBS) was not different (p > 0.05) with inoculum from wethers and goats [26.4 and 28.1 and 35.2 and 33.5 g bacterial N/kg digested CHO, respectively, obtained by using diamino pimelic acid (DAPA) and purine bases (PB) as microbial markers]. The lowest (p < 0.05) values were found in fermenters fed diets LHCOP and LH, estimated, respectively, from DAPA and PB (21.9 and 29.0 g bacterial N/kg digested CHO). The substitution of a part of lucerne hay by a concentrate including dried 2POC does not seem to cause important differences in efficiency of VFA production. Results concerning bacterial protein synthesis are not so clear since values estimated from DAPA and PB did not show similar trends. Neither inoculum origin nor PEG had important effects on fermentation characteristics. The DAPA could be an adequate marker in continuous fermenters, with comparative purposes, as protozoa are not present and, estimated protein synthesis values are similar to those obtained in vivo with similar diets using urinary excretion of PD (Yáñez Ruiz et al., 2004b). Further research is needed to state the optimal proportion of 2POC in practical diets for ruminants at both maintenance and production stages. [source]


Expression system for recombinant human growth hormone production from Bacillus subtilis

BIOTECHNOLOGY PROGRESS, Issue 1 2009
Tunçer H. Özdamar
Abstract We demonstrate for the first time, an expression system mimicking serine alkaline protease synthesis and secretion, producing native form of human growth hormone (hGH) from Bacillus subtilis. A hybrid-gene of two DNA fragments, i.e., signal (pre- ) DNA sequence of B. licheniformis serine alkaline protease gene (subC) and cDNA encoding hGH, were cloned into pMK4 and expressed under deg -promoter in B. subtilis. Recombinant-hGH (rhGH) produced by B. subtilis carrying pMK4::pre(subC)::hGH was secreted. N-terminal sequence and mass spectrometry analyses of rhGH confirm the mature hGH sequence, and indicate that the signal peptide was properly processed by B. subtilis signal-peptidase. The highest rhGH concentration was obtained at t = 32 h as CrhGH = 70 mg L,1 with a product yield on substrate YrhGH/S = 9 g kg,1, in a glucose based defined medium. Fermentation characteristics and influence of hGH gene on the rhGH production were investigated by comparing B. subtilis carrying pMK4::pre(subC)::hGH with that of carrying merely pMK4. Excreted organic-acid concentrations were higher by B. subtilis carrying pMK4::pre(subC)::hGH, whereas excreted amino-acid concentrations were higher by B. subtilis carrying pMK4. The approach developed is expected to be applicable to the design of expression systems for heterologous protein production from Bacillus species. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]


The effect of additives in silages of pure timothy and timothy mixed with red clover on chemical composition and in vitro rumen fermentation characteristics

GRASS & FORAGE SCIENCE, Issue 3 2003
M. Hetta
Abstract The aim was to compare the effects of additives on direct cut silages of pure timothy and timothy mixed with tetraploid red clover. First and second growth cuts were ensiled during three consecutive years, 1994, 1995 and 1996, either without any additive or with the addition of formic acid, or lactic acid bacteria in combination with molasses. Effects of the additives on the degradation characteristics of the herbage and the silages were analysed using an automatic in vitro gas production (GP) technique. At the end of the in vitro procedures, organic matter and neutral-detergent fibre (NDF) degradabilities were determined. The tetraploid red clover persisted in the leys during the 3 years and was the dominant species at the second growth in the mixed leys. The herbage from the mixed crops had lower dry-matter contents, higher crude protein concentrations and higher buffering capacity compared with the pure timothy at both cuts. In general, the additives reduced pH, and the concentrations of ammonium-N and acetic acid in the silages. The treated silages had a more rapid faster GP in both crops. The silages from the mixed crop benefited more from the additives compared with the grass silages. The additives affected the soluble fractions as well as the NDF degradability of the silages of the mixed crop more than those fractions of the grass silages. The addition of molasses in combination with a commercial inocula resulted in increased production of lactic acid and ethanol in silages from both crops. The silages without additives could not meet the requirements for good silages according to the standards of the Swedish dairy industry. [source]


The effect of harvest date and inoculation on the yield, fermentation characteristics and feeding value of forage pea and field bean silages

GRASS & FORAGE SCIENCE, Issue 3 2001
M. D. Fraser
Two experiments describe the ensiling potential of whole-crop forage peas (Pisum sativum) and field beans (Vicia faba). In Experiment 1, forage peas (cv. Magnus) and field beans (cv. Mayo) were harvested at 10, 12 and 14 weeks after sowing, and ensiled in 10 kg mini-silos either untreated or treated with an inoculant (Lactobacillus plantarum). In terms of yield and ensiling potential, the optimum growth stage for harvesting forage peas occurred at 12 weeks of growth. In contrast, delaying the harvest of field beans until 14 weeks gave the highest yields of dry matter (DM) and crude protein (CP). Changes in crop maturity had little effect on the chemical composition of the fresh forages, but between-harvest date differences were observed in the DM, ammonia-N, CP, water-soluble carbohydrates (WSC), acid-detergent fibre (ADF), neutral-detergent fibre (NDF), lactic acid and volatile fatty acids (VFA) concentrations and pH of the corresponding silages. Fermentation was improved by applying an inoculant. In Experiment 2, forage peas and field beans were harvested at 14 weeks after sowing and ensiled as round-bale silage, either untreated or treated with an inoculant. The yields of the crops were similar, and the only difference in the chemical composition of the wilted forages was a higher CP concentration in the field beans. However, after the ensiling process was complete, the forage pea silages were found to have significantly higher DM, WSC, starch and butyric acid concentrations compared with the field bean silages, and lower ammonia-N, CP, ADF, acetic acid and lactic acid concentrations. Inoculation was found to increase the lactic acid concentration and reduce the pH and ammonia-N and acetic acid concentrations of the silages. Each of the silages produced in Experiment 2 was offered to six Suffolk crossbred wether lambs, aged 10 months. Voluntary DM intakes were similar on all treatments, despite the apparent digestibility of the forage pea silages being significantly higher than that of the field bean silages. Nitrogen retention was higher for lambs offered forage pea silage. Application of an inoculant was found to have a negative effect on the amount of N retained, indicating the necessity for more detailed investigations into proteolytic activity within these crops during the fermentation process. [source]


Effect of probiotic Lactobacillus casei Zhang on fermentation characteristics of set yogurt

INTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2010
JICHENG WANG
The effect of four inoculation levels of Lactobacillus casei Zhang (0.001, 0.01, 0.1 and 1.0 g/100 g) on the fermentation characteristics of set-style yogurt, and the changes in viable counts of lactic acid bacteria, pH value, syneresis, apparent viscosity, sugar and organic acid contents were determined during fermentation and storage over 21 days. The presence of 0.001 to 0.01 g/100 g L. casei Zhang did not affect the growth of the yogurt strains, and the yogurt inoculated with 0.00 1 g/100 g of L. casei Zhang had the highest apparent viscosity among the samples. However, a high inoculated level of L. casei Zhang (1.0 g/100 g) resulted in yogurts with inferior quality. [source]


Effect of supplemental Bacillus cultures on rumen fermentation and milk yield in Chinese Holstein cows

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 4 2010
G. H. Qiao
Summary Two experiments were conducted to study the effect of supplemental 100 g/day of live Bacillus cultures (2 × 1011 cell of Bacillus subtilis and Bacillus licheniformis) on rumen fermentation as well as milk yield and composition in Chinese Holstein cows. In experiment 1, investigating 3 × 10 cows, milk yield and milk protein were increased by using B. licheniformis (p < 0.05) in comparison with an unsupplemented group and the B. subtilis group. Body weight was not significantly affected by Bacillus culture supplementation (p > 0.05). Percentage of milk fat and lactose was not significantly different between treatments (p > 0.05). But milk protein increased with B. licheniformis supplementation (p < 0.05). In experiment 2, carried out with three non-lactating ruminally and duodenally fistulated cows, results showed that B. licheniformis supplementation increased microbial crude protein flow into duodenum (p < 0.05) and decreased the ammonia nitrogen concentration in ruminal fluid at 0.5 h, 1 h, 3 h, 6 h after morning feeding (p < 0.05). Bacillus licheniformis supplementation increased total VFA and acetate concentration in ruminal fluid at 0.5 h, 1 h, 3 h, 6 h after morning feeding (p < 0.05). Bacillus subtilis had no significant effect on rumen fermentation characteristics, duodenal microbial N flow and ruminal apparent nutrient digestibility (p > 0.05). Bacillus licheniformis increased ruminal apparent nutrient digestibility of neutral detergent fibre, acid detergent fibre, and organic matter (p < 0.05). [source]


Effect of different liquid cultures of live yeast strains on performance, ruminal fermentation and microbial protein synthesis in lambs

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 6 2008
M. K. Tripathi
Summary Three yeast strains, Kluyveromyces marximanus NRRL-3234 (KM), Saccharomyces cerevisiae NCDC-42 (SC) and Saccharomyces uvarum ATCC-9080 (SU), and a mixed culture (1:1:1 ratio) were evaluated for their value as probiotics in lamb feeding in two experiment. In experiment I and II, 20 and 30 pre-weaner lambs were fed for 63 and 60 days in two and three equal groups respectively. All lambs were offered ad libitum a creep mixture and Zizyphus nummularia leaves, and yeasts were dosed orally. In experiment I, one group received no yeast, the other of the mixed culture (1.5,2 × 1010 live cells/ml). In experiment II, yeast cultivation was modified yielding 1.5,2 × 1013 live cells/ml. Lambs of the three experimental groups received 1 ml/kg live weight of one of the individual yeasts. Feed intake did not differ among groups of both experiments with the exception of SC-supplemented lambs in experiment II which showed a trend to higher intakes per kg metabolic body weight and in percentage of body weight when compared with KM- and SU-supplemented lambs. Supplementation of the mixed yeast culture had no effect on intakes of digestible crude protein and metabolisable energy, nutrient digestibility, nitrogen balance and rumen fermentation characteristics (pH, ammonia, volatile fatty acid concentration, protozoa count) and urinary allantoin as an indicator of microbial protein synthesis. The same was true for comparisons in experiment II except ciliate protozoa counts, which showed a trend to be the highest with SU and the lowest with SC. The results of present study show that the response of lambs to supplemented live yeast cultures is inconsistent, as it lacked to have an effect in the present study, and that differences among strains were small, even when supplemented at a much higher live cell count. [source]


Fermentation characteristics and microbial growth promoted by diets including two-phase olive cake in continuous fermenters

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1 2008
A. Moumen
Summary Two-phase olive cake (2POC) is the by-product obtained from the so called ,two-phase' procedure to extract olive oil by mechanical methods. After the mechanical extraction the 2POC is dried and most of the remaining oil extracted by chemical means. The production of the crude by-product may reach more than 4 millions t/year in Spain (MAPA, 2003), most of it in areas (Southeast) with shortage of pastures and conventional feeds for ruminants. Six continuous fermenters, inoculated with ruminal liquor from wethers or goats, were fed lucerne hay (LH); LH plus a concentrate including dried two-phase olive cake (LHCO) and; diet LHCO added with polyethylene glycol (LHCOP). The highest pH values and ammonia N (NH3 -N) output were found in fermenters fed diet LH (6.19 and 6.35 for pH, and 53.7 and 68.9 mg NH3N/day, respectively, in fermentes inoculated with rumen liquor from sheep and goats) without differences due to the inoculum origin. The digestibility of carbohydrates (CHO) was affected (p < 0.001) by inoculum (67.0 and 58.8%, respectively, for goats and wethers) the lowest values being for diet LHCO (53.2 and 57.0% with inoculum from wethers and goats, respectively). The main volatile fatty acid (VFA) was acetic acid with higher (p < 0.01) values in fermenters with inoculum from goats than from wethers (80.2 and 63.0 mmol/day respectively). The efficiency of bacterial protein synthesis (EBS) was not different (p > 0.05) with inoculum from wethers and goats [26.4 and 28.1 and 35.2 and 33.5 g bacterial N/kg digested CHO, respectively, obtained by using diamino pimelic acid (DAPA) and purine bases (PB) as microbial markers]. The lowest (p < 0.05) values were found in fermenters fed diets LHCOP and LH, estimated, respectively, from DAPA and PB (21.9 and 29.0 g bacterial N/kg digested CHO). The substitution of a part of lucerne hay by a concentrate including dried 2POC does not seem to cause important differences in efficiency of VFA production. Results concerning bacterial protein synthesis are not so clear since values estimated from DAPA and PB did not show similar trends. Neither inoculum origin nor PEG had important effects on fermentation characteristics. The DAPA could be an adequate marker in continuous fermenters, with comparative purposes, as protozoa are not present and, estimated protein synthesis values are similar to those obtained in vivo with similar diets using urinary excretion of PD (Yáñez Ruiz et al., 2004b). Further research is needed to state the optimal proportion of 2POC in practical diets for ruminants at both maintenance and production stages. [source]


Effect of finishing diets on Escherichia coli populations and prevalence of enterohaemorrhagic E. coli virulence genes in cattle faeces

JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2005
R.A. Gilbert
Abstract Aim:, To determine the effect of different carbohydrate-based finishing diets on fermentation characteristics and the shedding of Escherichia coli and enterohaemorrhagic E. coli (EHEC) virulence genes in cattle faeces. Methods and Results:, The size of faecal E. coli populations and fermentation characteristics were ascertained in three experiments where cattle were maintained on a range of finishing diets including high grain, roughage, and roughage + molasses (50%) diets. Increased E. coli numbers, decreased pH and enhanced butyrate and lactate fermentation pathways were associated with grain diets, whereas roughage and roughage + molasses diets resulted in decreased concentrations of ehxA, eaeA and stx1 genes, this trend remaining at lairage. In one experiment, faecal E. coli numbers were significantly lower in animals fed roughage and roughage + molasses, than animals fed grain (4·5, 5·2 and 6·3 mean log10 g,1 digesta respectively). In a second experiment, faecal E. coli numbers were 2 log lower in the roughage and roughage + molasses diets compared with grain-fed animals prior to lairage (5·6, 5·5 and 7·9 mean log10 g,1 digesta respectively) this difference increasing to 2·5 log at lairage. Conclusions:, The type of dietary carbohydrate has a significant effect on E. coli numbers and concentration of EHEC virulence genes in faeces of cattle. Significance and Impact of the Study:, The study provides a better understanding of the impact finishing diet and commercial lairage management practices may have on the shedding of E. coli and EHEC virulence factors, thus reducing the risk of carcass contamination by EHEC. [source]


Influence of ciliate protozoa on biochemical changes and hydrolytic enzyme profile in the rumen ecosystem

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002
A. Santra
Aims:,To assess the effect of presence or absence of rumen protozoa on fermentation characteristics and enzyme profile in growing lambs. Methods and Results:,Weaner lambs (G1, G2, G3, G4, G5 and G6 groups) were defaunated by oral administration of sodium laurel sulphate (at 8 g 100 kg,1 body weight). The lambs of G4, G5 and G6 groups were refaunated. The roughage and concentrate ratio in the diet of G1 and G4, G2 and G5, and G3 and G6 were 50:50 (R1), 65:35 (R2) and 80:20 (R3), respectively. Daily dry matter intake was similar in defaunated and faunated lambs. However, digestibility of organic matter (OM), cellulose and gross energy were lower in defaunated lambs while crude protein (CP) digestibility was similar in both defaunated and faunated lambs. The rumen pH and NH3 -N were lower (P < 0·01) while TVFA, total-N and TCA-ppt-N were higher (P < 0·01), in defaunated lambs. Ruminal activity of carboxymethyl cellulase was lower (P < 0·01) in defaunated lambs and amylase, xylanase, protease and urease were similar in faunated and defaunated lambs. Nutrient utilization, rumen metabolites and ciliate protozoal count were higher, whereas digestibility of fibre fractions was lower in high rather than low concentrate fed lambs. The rumen protozoa present before defaunation were B-type and the protozoa which re-established on refaunation were also B-type. Conclusions:,Absence of ciliate protozoa decreased nutrient digestibility and increased ruminal TVFA and total-N with lower NH3 -N concentration, indicating better energy and protein utilization in defaunated lambs. Significance and Impact of the Study: Defaunation improved energy and protein utilization in lambs. [source]


Fermentative production of L(+)-lactic acid from starch hydrolyzate and corn steep liquor as inexpensive nutrients by batch culture of Enterococcus faecalis RKY1

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2008
Young-Jung Wee
Abstract BACKGROUND: Attempts were made to determine the lactic acid production efficiency of novel isolate, Enterococcus faecalis RKY1 using four different starches (corn, tapioca, potato, and wheat starch) with different concentrations (50, 75, 100, and 125 g L,1) and corn steep liquor as an inexpensive nitrogen source. RESULTS: The yield of lactic acid from each starch was higher than 95% based on initial starch concentrations. High lactic acid concentration (129.9 g L,1) and yield (1.04 g-lactic acid g,1 -starch) were achieved faster (84 h) from 125 g L,1 of corn starch. Among the starches used, tapioca starch fermentation usually completed in a shorter incubation period. The final dry cell weight was highest (7.0 g L,1) for the medium containing 75 g L,1 of corn starch, which resulted in maximum volumetric productivity of lactic acid (3.6 g L,1 h,1). The addition of 30 g L,1 corn steep liquor supplemented with a minimal amount of yeast extract supported both cell growth and lactic acid fermentation. CONCLUSION:Enterococcus faecalis RKY1 was found to be capable of growing well on inexpensive nutrients and producing maximum lactic acid from starches and corn steep liquor as lower-cost raw materials than conventionally-used refined sugars such as glucose, and yeast extract as an organic nitrogen source in laboratory-scale studies. These fermentation characteristics are prerequisites for the industrial scale production of lactic acid. Copyright © 2008 Society of Chemical Industry [source]


Evaluation of alternative cereal sources in dog diets: effect on nutrient utilisation and hindgut fermentation characteristics

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2009
Kumar B Kore
Abstract BACKGROUND: Rice is one of the most commonly used cereal grains in pet foods. However, other cereals such as pearl millet, sorghum and maize have good amino acid profiles and could be used as alternatives to rice in the diet of dogs, thus sparing rice for human consumption. The aim of this study was to evaluate the nutritional worth of these cereals for pet dogs. RESULTS: Eight adult Spitz dogs (age ,10 months, average body weight 6.14 ± 0.58 kg) were used in a 4 × 4 replicated Latin square design to compare the effects of dietary inclusion of four cereals, namely rice, maize, pearl millet and sorghum, on digestibility and hindgut fermentation characteristics. The digestibility of dry matter (DM) was significantly (P < 0.01) reduced when rice was replaced by the alternative cereals. Additionally, the digestibilities of protein, fat and total dietary fibre decreased (P < 0.01) in dogs fed the pearl millet-based diet. The DM voided in faeces increased (P < 0.05) when rice was replaced by the alternative cereals. Faecal ammonia concentration was higher (P < 0.05) on the rice-based diet, while faecal lactate concentration was reduced (P < 0.01) on the pearl millet- and sorghum-based diets. CONCLUSION: The results suggest that maize, pearl millet and sorghum are not as effectively utilised as rice as cereal source in the diet of dogs. Copyright © 2009 Society of Chemical Industry [source]


In vitro gas production profile and the formation of end products from non- washable, insoluble washable and soluble washable fractions in some concentrate ingredients

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2007
Arash Azarfar
Abstract A procedure that mimics washing in the in situ incubation technique, combined with an in vitro gas and volatile fatty acids (VFAs) production technique, was used to verify the assumption that rumen degradation behaviour of material washed out of nylon bags is instantaneous and complete. In a 6 × 4 factorial arrangement of treatments with three replicates, fractions of maize, barley, milo, yellow peas, lupins (a mixture of white and spotted lupins) and round-seeded brown faba beans were subjected to an in vitro incubation technique. Fractions were whole (WHO), non-washable (NWF), insoluble washable (ISWF) and soluble washable (SWF). In a manually operated in vitro fermentation system, another 24 samples of the same substrates were fermented for VFA and ammonia analysis. Except in lupins, ISWF in the concentrate ingredients was very rich in starch. SWF was relatively rich in ash, crude protein, soluble sugars, and a residual unknown fraction but contained only a negligible quantity of starch. Thus, the fermentation characteristics of ISWF were more like WHO and NWF than SWF. Total gas production of SWF was considerably lower than the other fractions. A very rapidly degradable fraction was seen in the first phase of degradation of SWF. The pattern of fermentation end-product formation for SWF differed from that of the other fractions. Copyright © 2007 Society of Chemical Industry [source]


Influence of replacing brewers' grains with green tea grounds on feed intake, digestibility and ruminal fermentation characteristics of wethers

ANIMAL SCIENCE JOURNAL, Issue 2 2008
Chuncheng XU
ABSTRACT An experiment was conducted to examine feed intake, apparent digestibility, nitrogen balance, ruminal fermentation and blood components of wethers fed diets containing increasing levels of wet green tea grounds (WGTG). The experimental design was a 4 × 4 Latin square with four wethers in four 15-day periods. Wethers were allowed access to diets ad libitum, and allotted to one of four treatments in which WGTG replaced 0% (no WGTG added, CTG), 5% (low level, LBG), 10% (medium level, MTG), and 15% (high level, HTG) of total mixed ration (TMR) dry matter (DM) as wet brewers grains (WBG). All TMR silages were ensiled for 120 days and, irrespective of the WGTG addition, they were well preserved with a high lactic acid content, low pH and ammonia-N contents. There were no differences among treatments in feed intake, with the exception of ether extract intake (P = 0.032). Digestibilities for LTG and MTG treatments were not different from CTG. However, the organic matter, crude protein, acid detergent fiber and energy digestibilities for HTG treatment were lower than the CTG (P < 0.05). As the level of WGTG increased, nitrogen intake did not differ, but fecal nitrogen increased (P = 0.002), while urinary nitrogen decreased (P < 0.001). No differences among treatments were found in pH level and volatile fatty acids concentrations. However, the ruminal ammonia-N of the HTG silage was lower than for the CTG silage at all times (P < 0.05). Increasing concentrations of WGTG in the TMR silage decreased (P = 0.019) plasma urea nitrogen content. Therefore, the possible mixing proportion of WGTG for TMR silages can be 10% of the diet DM. [source]


Good modeling practice for PAT applications: Propagation of input uncertainty and sensitivity analysis

BIOTECHNOLOGY PROGRESS, Issue 4 2009
Gürkan Sin
Abstract The uncertainty and sensitivity analysis are evaluated for their usefulness as part of the model-building within Process Analytical Technology applications. A mechanistic model describing a batch cultivation of Streptomyces coelicolor for antibiotic production was used as case study. The input uncertainty resulting from assumptions of the model was propagated using the Monte Carlo procedure to estimate the output uncertainty. The results showed that significant uncertainty exists in the model outputs. Moreover the uncertainty in the biomass, glucose, ammonium and base-consumption were found low compared to the large uncertainty observed in the antibiotic and off-gas CO2 predictions. The output uncertainty was observed to be lower during the exponential growth phase, while higher in the stationary and death phases - meaning the model describes some periods better than others. To understand which input parameters are responsible for the output uncertainty, three sensitivity methods (Standardized Regression Coefficients, Morris and differential analysis) were evaluated and compared. The results from these methods were mostly in agreement with each other and revealed that only few parameters (about 10) out of a total 56 were mainly responsible for the output uncertainty. Among these significant parameters, one finds parameters related to fermentation characteristics such as biomass metabolism, chemical equilibria and mass-transfer. Overall the uncertainty and sensitivity analysis are found promising for helping to build reliable mechanistic models and to interpret the model outputs properly. These tools make part of good modeling practice, which can contribute to successful PAT applications for increased process understanding, operation and control purposes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]