Volatile Fatty Acid Profile Research Articles

Rhizosphere anode model explains high oxygen levels during operation of a Glyceria maxima PMFC

In this paper, the effect of root oxygen loss on energy recovery of the plant microbial fuel cell (PMFC) is described. In this manner, advanced understanding of competing processes within the rhizosphere-anode interface was provided. A microscopic model was developed on the basis of exudation, oxygen loss, biological oxidation, and biological current generation. The model was successfully validated by comparison to oxygen concentration profiles, volatile fatty acid profiles, and chemical oxygen demand profiles measured in the anode compartment.The model predicted oxic zones around roots in the anode of the plant microbial fuel cell. Results show no direct link between current generation and photosynthesis. This was consistent with the model which predicted that current was generated via hydrolysis of root-derived organic compounds. This result means that to optimize energy recovery of a PMFC, the plant selection should focus on high root biomass production combined with low oxygen loss.

The effect of dietary concentrate and soya oil inclusion on microbial diversity in the rumen of cattle

Methane emissions from ruminants are a significant contributor to global greenhouse gas production. The aim of this study was to examine the effect of diet on microbial communities in the rumen of steers. The effects of dietary alteration (50 : 50 vs 90 : 10 concentrate-forage ratio, and inclusion of soya oil) on methanogenic and bacterial communities in the rumen of steers were examined using molecular fingerprinting techniques (T-RFLP and automated ribosomal intergenic spacer analysis) and real-time PCR. Bacterial diversity was greatly affected by diet, whereas methanogen diversity was not. However, methanogen abundance was significantly reduced (P = 0.009) in high concentrate-forage diets and in the presence of soya oil (6%). In a parallel study, reduced methane emissions were observed with these diets. The greater effect of dietary alteration on bacterial community in the rumen compared with the methanogen community may reflect the impact of substrate availability on the rumen bacterial community. This resulted in altered rumen volatile fatty acid profiles and had a downstream effect on methanogen abundance, but not diversity. Understanding how rumen microbial communities contribute to methane production and how these microbes are influenced by diet is essential for the rational design of methane mitigation strategies from livestock.

Effect of roughage fibre content on fibrolytic activities and volatile fatty acid profiles of Neocallimastix sp. YAK11 isolated from rumen fluids of yak ( Bos grunniens)

A 10-day pure culture of Neocallimastix sp. YAK11, isolated from rumen fluids of yak ( Bos grunniens) was evaluated for fibrolytic activity, apparent dry matter disappearance (ADMD), ferulic acid, reducing sugars and volatile fatty acids (VFA). The fungus was grown on oat straw (OS), corn stalks (CS), rice straw (RS) and wheat straw (WS). Recovered activity of ferulic acid esterase peaked at day 5 in all roughages, and the lowest activity was found with low fibre OS throughout the incubation (P<0.0001). The recovered activity of acetyl esterase peaked at day 6 with WS and RS and at day 7 with CS and OS (P<0.0001). The highest acetyl esterase activity was found with high fibre WS throughout the incubation (P<0.0001). Xylanase activity increased with all roughages and was maintained at a high level throughout the incubation (P=0.0102). The lowest xylanase activity was found in WS (P<0.0001), but cultures grown on OS, CS and RS showed no differences. The highest ADMD and reducing sugar values occurred in OS and the lowest in WS (P<0.0001). Ferulic acid release did not differ between four roughages. ADMD was positively correlated with xylanase activity ( r = 0.51, P<0.01). Total VFA concentration was greatest in OS (P<0.0001) and highly correlated with fibrolytic enzyme activities ( r > 0.42, P<0.01). Molar proportions of acetate and valerate did not differ in the roughages. The lowest propionate and branch chained VFA levels occurred in WS (P=0.0115), and the highest butyrate levels occurred in OS throughout the 10-d incubation (P=0.0464). The highest ratio of non-glucogenic to glucogenic acids (NGR) occurred in WS (P=0.0481). NGR peaked for all roughages around day 3 and then slightly declined for the rest of the experiment. In general, the isolate was capable of a pronounced degradation that would depend on the fibre content of the roughages. Screening of fungi from rumen fluids of yak would appear to be a useful strategy to obtain highly active esterases and polysaccharide hydrolases.

Evaluation of models to predict the stoichiometry of volatile fatty acid profiles in rumen fluid of lactating Holstein cows

Volatile fatty acids (VFA), produced in the rumen by microbial fermentation, are the main energy source for ruminants. The VFA profile, particularly the nonglucogenic (acetate, Ac; butyrate, Bu) to glucogenic (propionate, Pr) VFA ratio (NGR), is associated with effects on methane production, milk composition, and energy balance. The aim of this study was to evaluate extant rumen VFA stoichiometry models for their ability to predict in vivo VFA molar proportions. The models were evaluated using an independent data set consisting of 101 treatments from 24 peer-reviewed publications with lactating Holstein cows. All publications contained a full diet description, rumen pH, and rumen VFA molar proportions. Stoichiometric models were evaluated based on root mean squared prediction error (RMSPE) and concordance correlation coefficient (CCC) analysis. Of all models evaluated, the 1998 Friggens model had the lowest RMSPE for Ac and Bu (7.2 and 20.2% of observed mean, respectively). The 2006 Bannink model had the lowest RMSPE and highest CCC for Pr (14.4% and 0.70, respectively). The 2008 Bannink model had comparable predictive performance for Pr to that of the 2006 Bannink model but a larger error due to overall bias (26.2% of MSPE). The 1982 Murphy model provided the poorest prediction of Bu, with the highest RMSPE and lowest CCC (24.6% and 0.15, respectively). The 1988 Argyle and Baldwin model had the highest CCC for Ac with an intermediate RMSPE (0.47 and 8.0%, respectively). The 2006 Sveinbjörnsson model had the highest RMSPE (13.9 and 34.0%, respectively) and lowest CCC (0.31 and 0.40, respectively) for Ac and Pr. The NGR predictions had the lowest RMSPE and highest CCC in the 2 models of Bannink, whereas the lowest predictive performance was in the 2006 Sveinbjörnsson model. It appears that the type of VFA produced is not a simple linear relationship between substrate inputs and pH as currently represented. The analysis demonstrates that most rumen VFA stoichiometric approaches explain a large part of the variation in VFA molar proportions among diets, in particular for Ac, whereas predictive power for Pr and Bu differ largely among approaches. The move toward feed evaluation systems based on animal response might necessitate an improved representation of rumen fermentation, focused on improving our understanding of VFA proportions in diets that vary from the mean.

Dynamics of transitional acidogenic community along with methanogenic population during anaerobic digestion of swine wastewater

The changes in bacterial communities associated with volatile fatty acids (VFAs) profiles were investigated in anaerobic batch reactors treating swine wastewater. Denaturing gradient gel electrophoresis and real-time PCR were used to analyze the bacterial community structure and the methanogenic population, respectively. The three subspecies of Lactobacillus delbrueckii ( bulgaricus, lactis, and indicus) along with the Clostridium-like organisms were identified. The L. delbrueckii-related organisms were assumed to be responsible for the fermentation of the organic compounds throughout the overall reaction period. The presence of Clostridium ultunense and Clostridium kluyveri, together with hydrogenotrophic methanogens, was essential for methane production from propionic acid in the later stage of the experiment. Our results show that the variations in VFA concentrations and methane production were complex and dynamic. We also demonstrate that an analysis of the acidogenic community, together with the methanogenic population, is essential for developing insight into the anaerobic digestion of swine wastewater.

The effects of starch and rapidly degradable dry matter from concentrate on ruminal digestion in dairy cows fed corn silage-based diets with fixed forage proportion

This study investigated the effects of the type (starch vs. nonstarch) and rate of ruminal degradation of carbohydrates from the concentrate on digestion in dairy cows fed corn silage-based diets. Six ruminally cannulated cows were assigned to 6 treatments in a 6 × 6 Latin square design. Treatments were arranged in a 3 × 2 factorial design. Two starch levels [25 and 41% dry matter (DM) for low starch (LS) and high starch (HS) diets, respectively] were obtained by replacing starch-rich feedstuffs by nonstarch feedstuffs. These starch levels were combined with slowly, moderately, and rapidly rumen-degradable feedstuffs to obtain 3 levels of rapidly degradable carbohydrates from concentrate (18, 23, and 28% DM). These levels were estimated from the DM disappearance of concentrate after 4h of in sacco incubation (CRDM). Wheat and corn grain were used as rapidly degradable and slowly degradable starch feedstuffs, respectively. Soybean hulls and citrus pulp were used as slowly degradable and rapidly degradable nonstarch feedstuffs, respectively. No interaction effect was found between dietary starch content and CRDM on pH range, volatile fatty acid (VFA) range, or VFA profile. Increasing CRDM led to a linear decrease in acetate-to-propionate ratio (from 2.7 to 2.1), and a linear increase in the pH and VFA ranges (from 0.86 to 1.12 pH units and from 34 to 56mM, respectively). Feeding HS diets decreased acetate-to-propionate ratio (2.6 vs. 2.0) and increased pH range (0.89 vs. 1.04 pH units), but had no effect on VFA range. Increasing CRDM linearly decreased mean ruminal pH in LS diets but linearly increased mean ruminal pH in HS diets. Fibrolytic activity was unaffected in LS diets but decreased strongly in HS diets (from 62 to 50%). These findings suggest that pH regulation differs on a short-term and on a longer-term basis. In the short-term, increasing CRDM increased the rate of VFA production, which may have been partly buffered under LS diets due to the higher cation exchange capacity of nonstarch feedstuffs compared with starch-rich feedstuffs. In the longer term, feeding starch reduced fibrolytic activity, which may have led to lower total VFA production and higher mean pH. The results of this experiment clearly show that both fermentative characteristics of the concentrate and dietary starch content should be taken into account when formulating diets to prevent subacute ruminal acidosis and to predict VFA profile.

Herbs, thyme essential oil and condensed tannin extracts as dietary supplements for broilers, and their effects on performance, digestibility, volatile fatty acids and organoleptic properties

1. Herbs, thyme essential oil (EO) and condensed tannin (CT) extracts were compared for their effects, as dietary supplements, on broiler growth performance, nutrient digestibility and volatile fatty acid (VFA) profiles in the gut. Cooked meat from the birds fed on diets with 4 herbs and an EO extract was compared by a taste panel against those fed on the control treatment, for organoleptic properties in the meat. 2. Female broiler chicks were fed on wheat-soybean meal diets from 0–42 d of age. These chicks were given either the basal diet (control), or the basal diet with one of rosemary, garlic or yarrow herbs, mimosa, cranberry or grapeseed CT's, or thyme EO supplements (8 treatments in total). Body weight (BW) and feed consumption (FC) were measured. 3. The garlic supplement tended to improve growth rate over the first 7 d, while mimosa CT and thyme EO supplements reduced weight gains. The mimosa supplement in diets significantly reduced FC to d 21. Meanwhile, the addition of a cranberry supplement reduced the digestibility of DM, OM and N, compared with the controls. Dietary thyme EO, yarrow, rosemary and garlic supplements modified caecal isovaleric and isobutyric acid proportions (presented as ‘Other VFA’; p < 0.05). Dietary herb significantly affected the intensity of meat flavour, and the potential of observing both garlic and abnormal flavours. There were large differences between the consumption of red and white meat samples, while meat temperature affected several flavour attributes. 4. Broiler performance and digestibility for birds given dietary garlic and grapeseed CT supplements were similar to the controls, and these supplements appear suitable for dietary inclusion. Careful choices are necessary when selecting dietary plant extract supplements for broilers, but beneficial effects can be observed.

In VitroStudies on the Effect of pH and Volatile Fatty Acid Concentration, as Influenced by Diet, on the Survival of Inoculated Nonacid- and Acid-AdaptedSalmonellain Bovine Rumen Fluid and Feces

The aim of this study was to examine the effect of pH and volatile fatty acids concentrations, as influenced by bovine diet, on the survival of Salmonella in inoculated rumen fluid and feces, thus providing preliminary data on the potential application of dietary manipulation as a preharvest control strategy to reduce Salmonella contamination at slaughter. The in vitro survival of nonacid- and acid-adapted (AA) Salmonella cocktails (Salmonella serovars: Dublin, Enteritidis, Newport, Typhimurium, and Typhimurium DT104) in rumen fluid and feces, collected from fistulated cattle fed five different diets ([1] grass, [2] grass + concentrate, [3] grass silage, [4] hay, and [5] a high grain diet), was examined at 6°C and 15°C (feces) and at 37°C (rumen fluid). The pH of the rumen fluid ranged from 5.77 to 6.61 and the feces from 6.86 to 7.06. Salmonella D-values in rumen fluid were statistically similar, regardless of dietary source. Although prolonged survival (up to 84 days) was observed in feces, diet did affect survival with significantly (p < 0.05) higher D-values obtained in feces from diets 3 and 4 (AA cells at 6°C) and significantly (p < 0.05) lower D-values for diet 5 (AA cells at 15°C). It was concluded that changes in rumen pH and volatile fatty acids profile and concentrations, based on dietary manipulation, may not reduce the persistence and dissemination of Salmonella in cattle.

Dietary sulfur concentration has no effect on In Vitro fermentative activity of ruminal mixed microorganisms

We previously reported that elevated concentrations of dietary sulfur (0.65% sulfur, dry basis) in finishing diets containing dried distillers grains with solubles decreased dry matter intake and average daily gains of feedlot cattle. Furthermore, high dietary sulfur concentrations yielded lower ruminal concentrations of volatile fatty acids, but were associated with increased ruminal ammonia concentrations and improved total tract digestibility of the diet. The objective of this study was to investigate, in culture tubes, effects of added sulfur on in vitro dry matter disappearance, volatile fatty acid profiles, and ammonia concentrations from substrates containing different sulfur concentrations when fermented by mixed ruminal microorganisms from a steer fed a diet based on corn and alfalfa.

Characteristics of physico-chemical properties, volatile compounds and free fatty acid profiles of commercial set-type Turkish yoghurts

Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volatile aroma compounds and free fatty acid profiles to compare their differences among the yoghurt products. The results showed that there were significant differences (P<0.05, 0.01, or 0.001) and variations in physico-chemical indices, volatile aroma compounds and volatile free fatty acid profiles among the yoghurt brands, which ultimately influence the flavor quality of the product. Acetaldehyde was predominant volatile compound in yoghurts, which followed by acetone, acetoin, diacetyl and ethanol. The level of diacetly was inversely related to titratable acidity, acetaldehyde and ethanoic acid. From ketones with high carbones 2-undecanone and 2-pentadecanone were higher than 2-butanone, 2-nanonane and 2-tridecanone. These ketones are related to fat content of yoghurt. Among short chain free fatty acids, ethanoic (acetic) acid was the most abundant in yoghurts, followed by hexanoic, octanoic and butanoic acids. These differences in detected chemical compositions of volatile compounds and free fatty acids would be applicable to predict flavor, nutritional value, quality control or shelf-life of the commmercial set-type Turkish yoghurts.

Effect of organic loading rate on VFA production, organic matter removal and microbial activity of a two-stage thermophilic anaerobic membrane bioreactor

This study focused on the VFA (volatile fatty acid) profile variation with organic loading rate (OLR) of a two stage thermophilic anaerobic membrane bioreactor (TAnMBR). The two stage TAnMBR treating high strength molasses-based synthetic wastewater was operated under a side-stream partial sedimentation mode at 55 °C. Reactor performances were studied at different OLR ranging from 5 to 12 kg COD m −3 d −1. Operational performance of TAnMBR was monitored by assessing biological activity, organic removal efficiency, and VFA. The major intermediate products of anaerobic digestion were identified as acetate, propionate, iso-butyrate, n-butyrate and valerate. Among them acetate and n-butyrate were identified as the most abundant components. Increase of OLR changes the predominant VFA type from acetic acid to n-butyric acid and the total VFA concentration was increased with increased OLR. Moreover, increased OLR increased organic removal efficiency up to second loading rate and dropped in third loading rate while biological activity was increased continuously.

Improvement of biohydrogen production by Enterobacter cloacae IIT-BT 08 under regulated pH

The present study investigates the effect of pH and intermediate products formation on biological hydrogen production using Enterobacter cloacae IIT-BT 08. Initial pH was found to have a profound effect on hydrogen production potential, while regulating the pH 6.5 throughout the fermentation was found to increase the cumulative hydrogen production rate and yield significantly. Modified Gompertz equation was used to fit the cumulative hydrogen production curves to obtain the hydrogen production potential P, the hydrogen production rate R and lag phase λ. At regulated pH 6.5, higher H 2 yield (3.1 mol H 2 mol −1 glucose), specific hydrogen production potential (798.1 mL/g) and specific rate of H 2 production (72.1 mL L −1 h −1 g −1) were obtained. The volatile fatty acid profile showed butyrate, ethanol and acetate as the major end metabolites of fermentation under the operating pH conditions tested; however, their pattern of distribution was pH dependent. At the optimum pH of 6.5, the acetate to butyrate ratio (A/B ratio) was found to be higher than that at any other pH. The study also investigates the effect of sodium ions on biohydrogen production potential. It was also found that sodium ion concentration up to 250 mM enhanced the hydrogen production potential; however, any further increase in the metal ion concentration had an inhibitory effect.

Correlation of Particular Bacterial PCR-Denaturing Gradient Gel Electrophoresis Patterns with Bovine Ruminal Fermentation Parameters and Feed Efficiency Traits

The influence of rumen microbial structure and functions on host physiology remains poorly understood. This study aimed to investigate the interaction between the ruminal microflora and the host by correlating bacterial diversity with fermentation measurements and feed efficiency traits, including dry matter intake, feed conversion ratio, average daily gain, and residual feed intake, using culture-independent methods. Universal bacterial partial 16S rRNA gene products were amplified from ruminal fluid collected from 58 steers raised under a low-energy diet and were subjected to PCR-denaturing gradient gel electrophoresis (DGGE) analysis. Multivariate statistical analysis was used to relate specific PCR-DGGE bands to various feed efficiency traits and metabolites. Analysis of volatile fatty acid profiles showed that butyrate was positively correlated with daily dry matter intake (P < 0.05) and tended to have higher concentration in inefficient animals (P = 0.10), while isovalerate was associated with residual feed intake (P < 0.05). Our results suggest that particular bacteria and their metabolism in the rumen may contribute to differences in host feed efficiency under a low-energy diet. This is the first study correlating PCR-DGGE bands representing specific bacteria to metabolites in the bovine rumen and to host feed efficiency traits.

Decrease of ruminal methane production in Rusitec fermenters through the addition of plant material from rhubarb (Rheum spp.) and alder buckthorn (Frangula alnus)

Roots of rhubarb (Rheum spp.) and bark of alder buckthorn (Frangula alnus) were tested as feed additives for decreasing ruminal methane production released from anaerobic fermentation of a forage-based diet in a rumen-simulating fermenter (Rusitec). Sixteen fermentation units (vessels) were set up for the experiment lasting 19 d. Treated vessels were supplied with 1g/d of rhubarb or alder buckthorn (4 vessels per plant species); another 4 vessels received 12μM sodium monensin (positive control), and the remaining 4 vessels were controls (no additive). Upon termination of the experimental period, batch cultures were inoculated with the liquid contents of the vessels for examining in vitro fermentation kinetics of cellulose, starch, barley straw, and the same substrate used in the Rusitec cultures. Monensin induced changes in fermentation in agreement with those reported in the literature, and inocula from those cultures decreased the fermentation rate and total gas produced in the gas kinetics study. Rhubarb decreased methane production, associated with limited changes in the profile of volatile fatty acids throughout the duration of the study, whereas digestibility and total volatile fatty acids production were not affected. Rhubarb inocula did not affect gas production kinetics except for cellulose. Alder buckthorn decreased only methane concentration in fermentation gas, and this effect was not always significant. The use of rhubarb (milled rhizomes of Rheum spp.) in the diets of ruminants may effectively modulate ruminal fermentation by abating methane production, thus potentially involving productive and environmental benefits.

Effect of sanitary conditions and dietary fibre on the adaptation of gut microbiota after weaning

At weaning, the intestinal microbial ecosystem has to adapt to new feeds and to a new environment. The diverse and abundant commensal microbiota and its production of volatile fatty acids (VFA), especially butyrate, are involved in the prevention of diarrhoea and defence against pathogens. This study investigated the effects of the level of dietary fibre (DF) and sanitary housing conditions on the microbiota of weaned pigs. Forty-eight piglets, weaned at 28 days of age, were housed in clean or poor conditions. They were fed during two consecutive phases, two diets containing a high level (16.9 then 21.7% total dietary fibre-TDF, mainly soluble) or a low level DF (control, 12.1 then 14.6% TDF). Five weeks after weaning, microbiota was analysed using counting techniques and VFA profiles were determined by gas chromatography in faeces collected from the rectum. When compared with the clean conditions, the faeces of piglets housed in the poor environment contained significantly more Lactobacillus and Enterobacteria and less anaerobic sulphite-reducing bacteria (+ 0.9, + 1.1, −2.1 Log 10 CFU/g faeces), 60% more total VFA, with proportionally less acetate and more butyrate (−3%, + 4%). The introduction of DF did not affect the composition of the microbiota, tended to increase total VFA (25%), and decreased the level of branched-chain VFA (−1.4%). To conclude, the degraded sanitary housing conditions and to a lesser degree DF, stimulated the bacterial ecosystem in a way that could be beneficial for digestive balance, despite their negative impact on animal performances.

The effects of forage proportion and rapidly degradable dry matter from concentrate on ruminal digestion in dairy cows fed corn silage–based diets with fixed neutral detergent fiber and starch contents

This study investigated the effects of the forage-to-concentrate (F:C) ratio and the rate of ruminal degradation of carbohydrates from the concentrate on digestion in dairy cows fed corn silage–based diets. Six cows with ruminal cannulas were assigned to 6 treatments in a 6×6 Latin square. Treatments were arranged in a 3×2 factorial design. Three proportions of neutral detergent fiber from forage [FNDF; 7.6, 13.2, and 18.9% of dry matter (DM)] were obtained by modifying F:C (20:80, 35:65, and 50:50). These F:C were combined with concentrates with either high or low content of rapidly degradable carbohydrates. The dietary content of rapidly degradable carbohydrates from the concentrate was estimated from the DM disappearance of concentrate after 4h of in sacco incubation (CRDM). Thus, 2 proportions of CRDM were tested (20 and 30% of DM). Wheat and corn grain were used as rapidly and slowly degradable starch sources, respectively. Soybean hulls and citrus pulp were used as slowly and rapidly degradable fiber sources, respectively. Concentrate composition was adjusted to maintain dietary starch and neutral detergent fiber contents at 35.9 and 28.9% of DM, respectively. There was no effect of the interaction between F:C and CRDM on DM intake (DMI), ruminal fermentation, chewing activity, and fibrolytic activity. When F:C decreased, DMI increased, the mean ruminal pH linearly decreased, and the pH range linearly increased from 0.95 to 1.27 pH unit. At the same time, the acetate-to-propionate ratio decreased linearly. Decreasing F:C linearly decreased the average time spent chewing per kilogram of DMI from 35.2 to 19.5min/kg of DMI and decreased ruminal liquid outflow from 11.6 to 9.2L/kg of DMI, suggesting a decrease in the salivary flow. Increasing CRDM decreased DMI and increased the time during which pH was below 6.0 (3.1 vs. 4.8h), the pH range (0.90 vs. 1.33), and the initial rate of pH drop. It also increased the volatile fatty acid range (35 vs. 59mM), thus suggesting an increased rate of fermentation. It also decreased the acetate-to-propionate ratio (2.9 vs. 1.8). Increasing CRDM barely affected the average time spent chewing per kilogram of DMI and the ruminal liquid outflow. These results suggest that rumen pH is controlled by different mechanisms when F:C is decreased or when CRDM is increased. Consequently, FNDF is a good predictor of the chewing time, whereas CRDM is a good predictor of the pH range and volatile fatty acid profiles. Finally, considering both FNDF and CRDM improves the prediction of mean pH.

Fecal Trimethylamine, Lactate and Volatile Fatty Acid Concentrations and Their Relationships with Diarrhea in Newborn Dairy Calves

To clarify the significance of fecal trimethylamine, lactate and volatile fatty acids (VFAs) in fermentative development of the hindgut in neonatal calves and the occurrence of diarrhea, 143 fecal samples (47 diarrheic, 93 normal and 3 meconium) were collected from 58 dairy calves fed milk. An additional 20 fecal samples were obtained from 10 weaned calves aged 13 to 18 weeks. Fecal pH, trimethylamine, ammonia, lactate and VFAs were analyzed. Compared with weaned calves, the trimethylamine level was higher in milk-fed calves and was associated with a large number of cases of diarrhea, but it had little relationship with the fecal ammonia level. Feces collected from the youngest (<2 weeks age) calves were more acidic and were associated with a higher lactate concentration. Lactic fermentation and fecal acidity were tremendously accelerated, particularly in diarrhea. Despite large fluctuations, the VFA concentrations were lower in diarrheic than in normal feces. In diarrheic feces at the youngest stage, the lower proportion of n-butyrate in the VFAs was accompanied by the elevated proportion of acetate. However, the fermentative differences between the diarrheic and normal feces were less apparent with advancing age. Thus, the fecal lactate and VFA profiles revealed marked changes with advancing age and suffering from diarrhea. Upon comparison with weaned calves, the trimethylamine level was clearly higher in the milk-fed calves and showed huge elevations in diarrheic cases.

Acetone and Isopropanol in Ruminal Fluid and Feces of Lactating Dairy Cows

Acetone and its metabolite isopropanol are produced by gut microbes as well as by the host's metabolism. To evaluate the production of acetone and isopropanol in alimentary tracts, a total of 80 pair-samples of feces and ruminal fluid were taken in lactating dairy cows that had been fed silage-containing diets. Acetone and isopropanol were analyzed, together with ethanol and volatile fatty acids (VFAs). Isopropanol was detected in 57 fecal and all the ruminal samples; however, the ruminal isopropanol and ethanol concentrations were distinctly lower than those in the feces. Acetone was detected in 13 fecal and 53 ruminal samples; however, there was no significant difference in acetone concentrations between the feces and the ruminal fluid. The group with higher fecal isopropanol concentration showed higher fecal proportions of acetate accompanied by low proportion of minor VFA, which consisted of isobutyrate and iso- and n-valerate. In the group with higher ruminal isopropanol concentration, ethanol concentration was higher; the ruminal VFA profiles showed only a negligible difference. Fecal and ruminal ethanol concentrations were not affected by feed ethanol. Thus, the colon showed an accelerated alcoholic fermentation compared with the rumen of dairy cows; however, acetone was present at higher frequency in the rumen than in the feces.

Microbial Population and Fermentation Characteristic in Response to Sapindus rarak Mineral Block Supplementation

This experiment was conducted to evaluate the effect of supplementation with lerak extract combined with mineral block on protozoal and bacterial population, and fermentation characteristic in vitro. The experimental design was completely randomized block design with 3 treatments and 4 replications. Control diet was a substrate that consisted of concentrate, forage and feed block with ratio 50 : 48 : 2, respectively. The treatments as a substrate were: control diet (C), C + 0.09% lerak extract, and C + 0.18% lerak extract from the total ration. Variables observed were protozoal and bacterial population, dry matter and organic matter degradability, N-NH3 and total volatile fatty acid (VFA) concentration. Data were analyzed using analysis of variance (ANOVA). The result showed that there were no significant effect (P&gt;0.05) for all parameter measured with lerak extract supplementation up to 0.18% in the presence of mineral block. However, supplementation of lerak extract 0.18% only slightly reduced protozoal numbers but tended to increase bacterial numbers. Dry matter and organic matter degradability and concentration of N-NH3 were similar among treatments. Volatile fatty acids profile changed which propionate tended to increase and acetate tended to decrease and ratio of acetate to propionate tended to decrease. In conclusion, addition of lerak extract up to 0.18% from total ration in the presence of mineral block was not yet effective to depress protozoal population, but could modify fermentation characteristic in vitro.

Effect of coconut oil and garlic powder on in vitro fermentation using gas production technique

An in vitro gas technique trial was conducted to investigate the effect of coconut oil (Co), garlic powder (G) and their mixtures on in vitro fermentation. Incubation was carried out using rumen fluid obtained from swamp buffaloes. The experimental design was a completely randomized design (CRD). The dietary treatments were ratio of Co and G supplementation at 0:0, 16:0, 8:4, 4:8 and 0:16 mg with rice straw as a roughage source. Cumulative gas production was recorded at 0, 2, 4, 6, 8, 12, 18, 24, 36, 48, 60 and 72 h of incubation. In vitro true digestibility (IVTD) was determined after 48 h incubation. Cumulative gas production at 72 h was significantly lowest ( P < 0.05) at Co:G, 16:0 mg. Garlic powder supplementation at 16 mg decreased ( P < 0.05) NH 3–N concentration and increased ( P < 0.05) in vitro true digestibility (IVTD) while supplemented coconut oil at 16 mg decreased ( P < 0.05) IVTD. Total volatile fatty acids (VFAs) were lowest ( P < 0.05) by garlic powder supplementation at 16 mg. However, supplementation of Co:G, 8:4, 4:8 and 0:16 mg tended to increase the proportion of propionate, decrease C2:C3 ratio and reduce ( P < 0.05) methane (CH 4) production. Protozoal population was significantly lowest ( P < 0.05) at Co:G, 8:4 mg. Moreover, application of quantitative PCR to quantify predominant cellulolytic bacteria (16S rRNA) and fungi (18S rRNA) targets revealed that treatments did not have an effect on Ruminococcus flavefaciens and total fungi population. However, it was found that supplementation of Co:G at 8:4 mg increased Ruminococcus albus population ( P < 0.05). Based on this study, it suggests that supplementation of Co:G at 8:4 and 0:16 mg could improve ruminal fluid fermentation in terms of volatile fatty acid profile, reduced methane losses and reduced protozoal population.