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Fructo-oligosaccharide (FOS) and citrus pectin (CP) are soluble fibers with different chemical composition. However, their fermentation pattern in the large intestine remains unclear. An in vitro batch fermentation using colonic digesta from pigs as inoculum was employed to investigate the fermentation dynamics of FOS and CP. The monosaccharides and SCFAs contents were assayed by high-performance liquid chromatography and gas chromatography, respectively. And the microbiota community was assessed by 16S rRNA gene high-throughput sequencing. Both FOS and CP were degraded after 6 h; FOS to a negligible level. The FOS group showed higher abundances of butyrate-producing bacteria such as Eubacterium rectale , Roseburia faecis and Coprococcus comes and butyrate compared to CP. CP stimulated the growth of pectinolytic microbes Lachnospira pectinoschiza , succinate-producing bacteria Succinivibrio dextrinosolvens , succinate-utilizing bacteria Phascolarctobacterium succinatutens and the production of acetate and propionate compared to FOS. Moreover, the relative abundances of key enzymes (e.g. butyrate kinase) involved in butyrate formation via the butyrate kinase route were upregulated in the FOS group, and the key enzymes (e.g. acetyl-CoA synthetase) associated with propionate production through the succinate pathway were upregulated in the CP group. FOS was preferable for fermentation by butyrate-producing bacteria to yield a higher level of butyrate via the butyrate kinase pathway, while CP enhanced the cross-feeding of succinate-producing and succinate-utilizing bacteria to form propionate through the succinate pathway. These findings deepen our understanding of the fermentation characteristics of the soluble fibers, and also provide guidelines for fiber choice in precisely modulating the microbial composition and metabolism in large intestine. • Fructo-oligosaccharide and citrus pectin showed the differential fermentation characteristics by the colonic inoculum from pig. • Fructo-oligosaccharide preferred to be fermented to produce a higher level of butyrate via the butyrate kinase pathway. • Cirtus pectin was fermented by cross-feeding to yield propionate through the succinate pathway. [ABSTRACT FROM AUTHOR]

Abstract Background Catabolite control protein A (CcpA) regulates the transcription of lactate dehydrogenase and pyruvate formate-lyase in Streptococcus bovis, but knowledge of its role in response to different pH is still limited. In this study, a ccpA-knockout strain of S. bovis S1 was constructed and then used to examine the effects of ccpA gene deletion on the growth and fermentation characteristics of S. bovis S1 at pH 5.5 or 6.5. Results There was a significant interaction between strain and pH for the maximum specific growth rate (μmax) and growth lag period (λ), which caused a lowest μmax and a longest λ in ccpA-knockout strain at pH 5.5. Deletion of ccpA decreased the concentration and molar percentage of lactic acid, while increased those of formic acid. Strains at pH 5.5 had decreased concentrations of lactic acid and formic acid compared to pH 6.5. The significant interaction between strain and pH caused the highest production of total organic acids and acetic acid in ccpA-knockout strain at pH 6.5. The activities of α-amylase and lactate dehydrogenase decreased in ccpA-knockout strain compared to the wild-type strain, and increased at pH 5.5 compared to pH 6.5. There was a significant interaction between strain and pH for the activity of acetate kinase, which was the highest in the ccpA-knockout strain at pH 6.5. The expression of pyruvate formate-lyase and acetate kinase was higher in the ccpA-knockout strain compared to wild-type strain. The lower pH improved the relative expression of pyruvate formate-lyase, while had no effect on the relative expression of acetate kinase. The strain × pH interaction was significant for the relative expression of lactate dehydrogenase and α-amylase, both of which were highest in the wild-type strain at pH 5.5 and lowest in the ccpA-knockout strain at pH 6.5. Conclusions Overall, low pH inhibited the growth of S. bovis S1, but did not affect the fermentation pattern. CcpA regulated S. bovis S1 growth and organic acid fermentation pattern. Moreover, there seemed to be an interaction effect between pH and ccpA deletion on regulating the growth and organic acids production of S. bovis S1.

The use of probiotics for farm animals has increased considerably over the last 25 years. The study was conducted to evaluate the effect of probiotics (Saccharomyces cerevisiae 2 × 1010 cfu/g + Lactobacillus acidophilus 6 × 109 cfu/g) on the rumen microflora, fermentation pattern and the enzyme activity. A 90 day feeding trial was conducted in the Corriedale sheep which were fed paddy straw based complete feed mixed with probiotics (Saccharomyces cerevisiae 2 × 1010 cfu/g + Lactobacillus acidophilus 6 × 109 cfu/g). The complete feed without probiotics served as a control. The real-time PCR allowed us to observe the changes in the number of rumen microbes. The mean values of total bacterial, fibrolytic bacteria, fungi and protozoa count irrespective of period were significantly (p < 0.01) higher in probiotic mix supplemented group than in non-supplemented group. With respect to fermentation pattern, Rumen pH, TVFA, total nitrogen and TCA perceptible nitrogen were significantly (p < 0.01) higher in probiotic supplemented group than non-supplemented group. The enzyme activity viz., carboxymethyl cellulose, xylanase, amylase, glucosidase, acetyl esterase and protease were significantly higher (p < 0.05) in probiotic mix supplemented group as compared to non-supplemented group. This study contributes to understand the positive impact of probiotics on rumen microbial count, rumen fermentation parameters and the enzyme activity. [ABSTRACT FROM AUTHOR]

Background: Catabolite control protein A (CcpA) regulates the transcription of lactate dehydrogenase and pyruvate formate-lyase in Streptococcus bovis, but knowledge of its role in response to different pH is still limited. In this study, a ccpA-knockout strain of S. bovis S1 was constructed and then used to examine the effects of ccpA gene deletion on the growth and fermentation characteristics of S. bovis S1 at pH 5.5 or 6.5. Results: There was a significant interaction between strain and pH for the maximum specific growth rate (μmax) and growth lag period (λ), which caused a lowest μmax and a longest λ in ccpA-knockout strain at pH 5.5. Deletion of ccpA decreased the concentration and molar percentage of lactic acid, while increased those of formic acid. Strains at pH 5.5 had decreased concentrations of lactic acid and formic acid compared to pH 6.5. The significant interaction between strain and pH caused the highest production of total organic acids and acetic acid in ccpA-knockout strain at pH 6.5. The activities of α-amylase and lactate dehydrogenase decreased in ccpA-knockout strain compared to the wild-type strain, and increased at pH 5.5 compared to pH 6.5. There was a significant interaction between strain and pH for the activity of acetate kinase, which was the highest in the ccpA-knockout strain at pH 6.5. The expression of pyruvate formate-lyase and acetate kinase was higher in the ccpA-knockout strain compared to wild-type strain. The lower pH improved the relative expression of pyruvate formate-lyase, while had no effect on the relative expression of acetate kinase. The strain × pH interaction was significant for the relative expression of lactate dehydrogenase and α-amylase, both of which were highest in the wild-type strain at pH 5.5 and lowest in the ccpA-knockout strain at pH 6.5. Conclusions: Overall, low pH inhibited the growth of S. bovis S1, but did not affect the fermentation pattern. CcpA regulated S. bovis S1 growth and organic acid fermentation pattern. Moreover, there seemed to be an interaction effect between pH and ccpA deletion on regulating the growth and organic acids production of S. bovis S1. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of dried distillers grains with solubles (DDGS) and red-osier dogwood (ROD) extract on in vitro fermentation characteristics, nutrient disappearance, and microbial profiles using the rumen simulation technique. The experiment was a completely randomized design with a 2 × 2 factorial arrangement of treatments and four replicates per treatment. A basal diet [10% barley silage, 87% dry-rolled barley grain, and 3% vitamin and mineral supplement, dry matter (DM) basis] and a DDGS diet (as per basal diet with 25% of wheat DDGS replacing an equal portion of barley grain) were supplemented with ROD extract at 0 and 1% (DM basis), respectively. The experimental period was 17 d, consisting 10 days of adaptation and 7 days of data and sample collection. The substitution of wheat DDGS for barley grain did not affect gas production; disappearances of DM, organic matter, and crude protein; total volatile fatty acid (VFA) production; and microbial protein production. However, replacing barley grain with wheat DDGS increased (P = 0.01) fermenter pH and molar proportion of branched-chain VFA, switched (P = 0.06) the fermentation pattern to higher acetate production due to increased (P = 0.01) disappearance of neutral detergent fiber (NDF), and decreased (P = 0.08) methane (CH4) production. In the basal barley diet, the ROD extract increased the acetate to propionate (A:P) ratio (P = 0.08) and reduced the disappearance of starch (P = 0.06) with no effect on any other variables. No effects of ROD in the DDGS diet were observed. The number of operational taxonomic unit (OTUs) and the Shannon diversity index of the microbial community had little variation among treatments. Taxonomic analysis revealed no effect of adding the ROD extract on the relative abundance of bacteria at the phylum level with either the basal diet or DDGS diet, while at the genus level, the microbial community was affected by the addition of both DDGS and the ROD extract. Prevotella and Fibrobacter were the most abundant genera in the basal diet; however, Treponema became the most abundant genus with the addition of the ROD extract. These results indicated that the substitution of wheat DDGS for barley grain may mitigate enteric CH4 emissions. The trend of reduced starch fermentability and increased NDF disappearance with the addition of ROD extract suggests a reduced risk of rumen acidosis and an improvement in the utilization of fiber for cattle-fed high-grain diet.

Macrotyloma uniflorum (kulthi) seeds, Asparagus racemosus (shatavari) roots or Acacia concina (shikakai) pods were supplemented to total mixed rations (TMR) @ 0-3% (on DM basis) to assess the impact of herbal feed additives (HFAs) on the in vitro rumen fermentation pattern. The saponin content and 2, 2-diphenyl-1-picrylhydrazyl- hydrate (DPHH) antioxidant activity was highest in A. racemosus than other HFAs. But total phenols, non tannin phenols, true tannins, condensed tannins, vitamin C and flavanoid contents were highest inM. uniflorum and lowest in A. concina. The dose/level of supplementation of HFAs, irrespective of their nature did not affect net gas production (NGP) and availability of metabolizable energy (ME) from TMR, but digestibility of nutrients and partitioning factor (PF) decreased in comparison to the unsupplemented group. The total and individual volatile fatty acids (VFAs) production; and acetate to propionate ratio was improved when the TMR was supplemented with HFAs at 1% level. The methane and ammonia-N production was depressed at 2% level as compared to control group. Irrespective of the dose, the total VFAs, acetate, and propionate production was higher while ammonia-N decreased in M. uniflorum supplemented TMR than other HFAs supplemented groups. Methane production from the TMR was comparable in the diet supplemented with different HFAs, however, diet supplemented with M. uniflorum resulted in lower methane production. Amongst the tested HFAs, M. uniflorum was a richer source of most of the bio-active compounds. Based on in vitro fermentation parameters, M. uniflorum supplemented to TMR @ 2% gave the best results.

Abstract Butanol has been regarded as an important bulk chemical and advanced biofuel; however, large scaling butanol production by solventogenic Clostridium sp. is still not economically feasible due to the high cost of substrates, low butanol titer and yield caused by the toxicity of butanol and formation of by-products. Renewed interests in biobutanol as biofuel and rapid development in genetic tools have spurred technological advances to strain modifications. Comprehensive reviews regarding these aspects have been reported elsewhere in detail. Meanwhile, more wild type butanol producers with unique properties were also isolated and characterized. However, few reviews addressed these discoveries of novel wild type solventogenic Clostridium sp. strains. Accordingly, this review aims to comprehensively summarize the most recent advances on wild type butanol producers in terms of fermentation patterns, substrate utilization et al. Future perspectives using these native ones as chassis for genetic modification were also discussed.

The study was performed on six sheep fitted with a cannula in the rumen and re-entrant cannula in the duodenum; divided into three groups, two sheep in each. The animals were fed meadow hay and the concentrate alone or the same diet supplemented with rapeseed or linseed oils at a dose of 5% of the basal diet. Ruminal degradation of protein and acid detergent fibre were lower when sheep were fed rapeseed compared to linseed oil (P < 0.05). The addition of oils to diets caused increased ruminal degradation of fat (P < 0.01). The density of protozoa in the rumen at 2 or 4 h after feeding was lower than before feeding in each experimental group. The inclusion of rapeseed oil in the diet decreased the total number of ciliates and Entodinium spp. compared with control and animals fed linseed oil (P < 0.01). Before feeding, the concentration of Diplodinium and Ophryoscolex spp. were lower in sheep fed rapeseed oil compared to control (P < 0.05), and the number of Dasytricha species decreased 2 h after feeding linseed oil compared to animals fed rapeseed oil (P < 0.05). Each of the oil supplements decreased the bacterial mass in the rumen compared with control (P < 0.01). The addition of rapeseed oil to the diet decreased total volatile fatty acid and acetate concentrations in the rumen in comparison to control and sheep receiving linseed oil (P < 0.01). In both diets, the estimated emission of methane and carbon dioxide (P < 0.01) increased 2 and 4 h after feeding compared to that at 0 h. The oleic acid more strongly reduced protozoa and digestive processes in the rumen than linolenic acid. Nevertheless, the quantity of oils added was still too low to induce detectable changes in methane formation in the rumen.

Livestock production is a main source of anthropogenic greenhouse gases (GHG). The main gases are CH4 with a global warming potential (GWP) 25 times and nitrous oxide (N2O) with a GWP 298 times, that of carbon dioxide (CO2) arising from enteric fermentation or from manure management, respectively. In fact, CH4 is the second most important GHG emitted globally. This current scenario has increased the concerns about global warming and encouraged the development of intensive research on different natural compounds to be used as feed additives in ruminant rations and modify the rumen ecosystem, fermentation pattern, and mitigate enteric CH4. The compounds most studied are the secondary metabolites of plants, which include a vast array of chemical substances like polyphenols and saponins that are present in plant tissues of different species, but the results are not consistent, and the extraction cost has constrained their utilization in practical animal feeding. Other new compounds of interest include polysaccharide biopolymers such as chitosan, mainly obtained as a marine co-product. As with other compounds, the effect of chitosan on the rumen microbial population depends on the source, purity, dose, process of extraction, and storage. In addition, it is important to identify compounds without adverse effects on rumen fermentation. The present review is aimed at providing information about chitosan for dietary manipulation to be considered for future studies to mitigate enteric methane and reduce the environmental impact of GHGs arising from livestock production systems. Chitosan is a promising agent with methane mitigating effects, but further research is required with in vivo models to establish effective daily doses without any detrimental effect to the animal and consider its addition in practical rations as well as the economic cost of methane mitigation.

The study was performed on six sheep fitted with a cannula in the rumen and re-entrant cannula in the duodenum; divided into three groups, two sheep in each. The animals were fed meadow hay and the concentrate alone or the same diet supplemented with rapeseed or linseed oils at a dose of 5% of the basal diet. Ruminal degradation of protein and acid detergent fibre were lower when sheep were fed rapeseed compared to linseed oil (P < 0.05). The addition of oils to diets caused increased ruminal degradation of fat (P < 0.01). The density of protozoa in the rumen at 2 or 4 h after feeding was lower than before feeding in each experimental group. The inclusion of rapeseed oil in the diet decreased the total number of ciliates and Entodinium spp. compared with control and animals fed linseed oil (P < 0.01). Before feeding, the concentration of Diplodinium and Ophryoscolex spp. were lower in sheep fed rapeseed oil compared to control (P < 0.05), and the number of Dasytricha species decreased 2 h after feeding linseed oil compared to animals fed rapeseed oil (P < 0.05). Each of the oil supplements decreased the bacterial mass in the rumen compared with control (P < 0.01). The addition of rapeseed oil to the diet decreased total volatile fatty acid and acetate concentrations in the rumen in comparison to control and sheep receiving linseed oil (P < 0.01). In both diets, the estimated emission of methane and carbon dioxide (P < 0.01) increased 2 and 4 h after feeding compared to that at 0 h. The oleic acid more strongly reduced protozoa and digestive processes in the rumen than linolenic acid. Nevertheless, the quantity of oils added was still too low to induce detectable changes in methane formation in the rumen. [ABSTRACT FROM AUTHOR]

The vaginal microbiome plays an important role in women's reproductive health. Imbalances in this microbiota, such as the poorly defined condition of bacterial vaginosis, are associated with increased susceptibility to sexually transmitted infections and negative reproductive outcomes. Currently, a “healthy” vaginal microbiota in reproductive aged women is understood to be dominated by Lactobacillus , although “atypical” microbiomes, such as Bifidobacterium- dominated profiles, have been described. Despite these observations, vaginal bifidobacteria remain relatively poorly characterized, and questions remain regarding their actual abundance in the microbiome. In this study, we used quantitative PCR to confirm the relative abundance of Bifidobacterium in the vaginal microbiomes of healthy reproductive aged women (n = 42), previously determined by deep sequencing. We also isolated and phenotypically characterized vaginal bifidobacteria (n = 40) in the context of features thought to promote reproductive health. Most isolates were identified as B. breve or B. longum based on cpn 60 barcode sequencing. Fermentation patterns of vaginal bifidobacteria did not differ substantially from corresponding type strains of gut or oral origin. Lactic acid was produced by all vaginal isolates, with B. longum strains producing the highest levels, but only 32% of isolates produced hydrogen peroxide. Most vaginal bifidobacteria were also able to tolerate high levels of lactic acid (100 mM) and low pH (4.5 or 3.9), conditions typical of vaginal fluid of healthy women. Most isolates were resistant to metronidazole but susceptible to clindamycin, the two most common antibiotics used to treat vaginal dysbiosis. These findings demonstrate that Bifidobacterium is the dominant member of some vaginal microbiomes and suggest that bifidobacteria have the potential to be as protective as lactobacilli according to the current understanding of a healthy vaginal microbiome. [ABSTRACT FROM AUTHOR]

In order to determine the effect of ruminal degradation of maize crude protein obtained with two levels of nitrogen (300 and 400 kg ha-1) and two irrigation techniques (gravity and drip), dacron bags (10 x 18 cm) which contained 5 g of maize were used. By introducing a cannula, the bags were inoculated for 0, 3, 6, 12 and 24 h in the rumen of four heifers. A completely randomized design was applied with factorial arrangement 2x2 of the treatments (nitrogen and irrigation technique).There were not statistical differences between the interactions of the variables under study (P < 0.05).However, drip irrigation vs gravity (8.72 vs 8.05%) and fertilization with 400 vs 300 kg de N ha-1 (8.52 vs. 8.25 %) increased (P ≤ 0.05) the crude protein content of the grain. The treatments did not affect (P ≥ 0.21) the PC solubility (19.4 ± 2.85 %).The ruminal degradation of the maize CP in the different incubation times did not change (P ≥ 0.20) by the maize grain obtained by means of irrigation technique or N levels used in maize production. The ruminal degradation rate of CP (0.10 ± 0.03) did not change (P ≥ 0.13) by the treatments. The percentage of crude protein effectively degraded in the rumen (42.14 ± 2.83 %) was similar (P ≥ 0.48) between treatments. Although the schemes of nitrogen levels or irrigation technique can modify the crude protein content in the maize grain, this did not influence on the characteristics of ruminal degradation of its crude protein. [ABSTRACT FROM AUTHOR]

This study was completed to evaluate the effect of fenugreek seed ( Trigonella foenum; FS) and asparagus root ( Asparagus officinalis; AR) on in vitro nutrient digestibility and fermentation patterns. Different levels [0%, 5%, 10%, 15% and 20% of dry matter (DM)] of the medicinal plants were included using alfalfa hay (AH) as a basal substrate at different incubation times (12, 18, 24 and 48 h). Total phenolic components of AH, FS and AR were 5.9, 10 and 8.3 g/kg DM, whereas total tannins were 0.4, 3.8 and 1.5 g/kg DM, respectively. Corresponding values for saponins were 10.4, 27.3 and 40.3 g/kg DM. Fenugreek seed increased (p < 0.05) in vitro organic matter (OM) digestibility at different incubation times and decreased (p < 0.05) crude protein (CP) digestibility at 18 and 24 h of incubation. Asparagus root also increased (p < 0.05) in vitro OM digestibility and decreased (p < 0.05) CP digestibility at different incubation times. Neutral detergent fibre digestibility was increased (p < 0.05) by the addition of AR or FS at low levels, but decreased (p < 0.05) noticeably by increasing level of two plants in the basal substrate. Ammonia-N concentration was markedly reduced (p < 0.05) by the addition of AR at different incubation times, and this reduction was accompanied by the decrease in CP digestibility. True DM degradability and partitioning factor (ratio of substrate DM truly degraded to gas volume produced at different times of incubation) were increased, and total volatile fatty acid concentration and total gas production were decreased (p < 0.05) with the addition of FS (at 10% and 15% DM levels) or AR (at 5%, 10% and 15% DM levels) at different incubation times. Results suggest that FS and AR may have potential as feed additives to increase the efficiency of nutrients' utilization, particularly of nitrogen in ruminant diets. [ABSTRACT FROM AUTHOR]

Abstract: In 24h in vitro incubations with 25ml of buffered rumen fluid, four doses (0, 20.8, 41.6 and 83.3mg) of a DHA-edible algae product, Aquagrow-DHA, were examined in combination with sunflower (20mg) or linseed oil (20mg). One treatment contained no Aquagrow-DHA, linseed or sunflower oil and one was supplemented with Aquagrow-DHA (166.6mg) only. Addition of lard ensured that total fat content was constant among incubations. Increasing amounts of Aquagrow-DHA progressively inhibited CH4 to a maximum of 80% (P<0.001). Increased CH4 inhibition was accompanied by decreased acetate (P<0.001) and butyrate (P<0.001), and increased propionate (P<0.001) proportions, but also by depression of the short chain fatty acid (SCFA) production by 30% at the highest Aquagrow-DHA level (P<0.001). However, SCFA inhibition only occurred when the Aquagrow-DHA dose exceeded 41.6mg and CH4 production was reduced by about 30% (P<0.05) at this dose. Inhibitory effects were linked to the amount of unesterified polyunsaturated fatty acids, particularly docosahexaenoic acid. Incubations under partial H2 atmosphere suggested that a direct toxic effect to rumen methanogens was caused by higher amounts of unesterified DHA (>41.6mgAquagrow-DHA/incubation) only, whereas suppression of rumen methanogenesis at lower doses seemed to be indirect through a lack of substrate. This indicates bacteria providing H2 to the rumen methanogens to be more sensitive to unesterified DHA than rumen methanogens. [Copyright &y& Elsevier]

Abstract: Effects of starch type, feeding level and level of a mixed N source upon rumen fermentation were examined using an in vitro rumen simulation system (i.e., SIMCO) with a fluid volume of 1100ml and liquid dilution rate of approximately 0.07/h. Two sources of starch, two feeding levels and two levels of N were examined in an experiment following a 2×2×2 factorial arrangement of treatments. The starch sources were raw slowly degrading (R), and cooked fast degrading (C), potato starch and constituted 450g/kg diet dry matter (DM). The remaining was supplied in the form of a grass hay mixture. The feeding levels were 20 (DM20) and 40 (DM40) g DM/d and the diet N level was either low (N1) or high (N2), using peptone and ammonia salt additions in the buffer. Two simulations of 10 days each were completed. The amount of bicarbonate in buffer was varied according to feeding level, and pH (average 6.3) did not differ between treatments. An increased degradation rate of starch (R vs. C) depressed neutral detergent fibre (aNDFom) digestibility (0.46 vs. 0.36) and organic matter true digestibility (OMTD; 0.73 vs. 0.68), but there were no other treatment effects on digestibility. The VFA production efficiency (average 0.47g VFA/g OMTD) was not affected by the main treatments, although an interaction between starch type and feeding level occurred. A decline in protozoa rating over the 10 day simulations was more apparent at the lower feeding level (DM20), indicating poor growth conditions for protozoa. Higher microbial efficiency (11.0 vs. 8.9mg microbial N/g OMTD) and a higher proportion of propionate (272 vs. 207mmol/mol VFA) occurred at DM20 compared to DM40. Increased degradation rate of starch (i.e., R vs. C) resulted in an improved microbial N efficiency (8.8 vs. 11.2mg/g OMTD) and an increase in the proportion of propionate (226 vs. 253mmol/mol VFA) at the expense of acetate (610 vs. 591mmol/mol VFA). Increasing the level of N (i.e., N1 vs. N2) improved the microbial N efficiency (9.2 vs. 10.7mg/g OMTD) and increased the proportion of propionate (230 vs. 249mmol/mol VFA) and butyrate (100 vs. 119mmol/mol VFA) at the expense of acetate (629 vs. 572mmol/mol VFA). Interactions between starch type and N level upon VFA patterns were apparent. Results support earlier findings in that carbohydrate degradation rate is an important factor determining microbial growth rates and VFA distribution. [Copyright &y& Elsevier]

Abstract: Effects of proportions of neutral detergent fibre (aNDFom) and starch, as well as their degradation rates, on rumen fermentation were tested using an in vitro rumen simulation system (SIMCO). The in vitro system was designed to simulate selective particle retention and had an average fluid volume of 1150ml with a liquid dilution rate of approximately 0.07h−1. Two types of hay (aNDFom sources) and two types of starch were each included at two different levels in the diet and were examined in an experiment following a 2×2×2 factorial arrangement of treatments (eight diet combinations). The hay was either late-cut timothy (Phleum pretense L.) or early cut meadow grass (Poa pratensis L.), with ruminal in situ aNDFom digestion rates of 0.03–0.04 and 0.07–0.08h−1, respectively. The two starch types were raw (R) and cooked (C) potato starch with previously determined in vitro ruminal digestion rates of 0.04 and 0.20h−1, respectively. The starch levels were 300 and 600g/kg diet dry matter (DM) with the remaining being hay (282–682g/kg DM) and peptone (14–111g/kg DM). The aNDFom level varied among the diets with different starch levels and hay types. The peptone acted as a source of peptides and, together with ammonia salts from buffer, was used to balance the N contents of the diets. The feeding level for each of the eight vessels was 28g DM/d. Two 10-day simulations were made with the system. The average pH was higher (P<0.05) for all treatments with raw potato starch (6.19) versus cooked starch (6.07). Protozoa scores, on a qualitative scale, declined faster at the higher starch level. The aNDFom digestibility was, as expected, higher (P<0.001) for meadow hay (0.57) than timothy (0.32), and was also higher (P<0.001) at the lower starch level (0.54) versus the higher (0.35). Microbial protein production efficiency (mg microbial N/g organic matter truly digested) was higher for the faster degrading aNDFom (P<0.01) and starch (P<0.05) sources, but was not affected by starch level. Cooked starch resulted in a lower acetate proportion (449mmol/mol versus 591mmol/mol VFA; P<0.001) but higher proportions of propionate (297mmol/mol versus 236mmol/mol VFA; P<0.001), and butyrate (169mmol/mol versus 127mmol/mol VFA; P<0.01). Butyrate increased with starch level (127mmol/mol versus 169mmol/mol VFA; P<0.01), and was also higher for meadow hay versus timothy (168mmol/mol versus 128mmol/mol VFA; P<0.01). Interactions between the treatments demonstrate that the response in VFA pattern to starch level is dependent on starch and aNDFom sources. Substrates such as starch and aNDFom are fermented differently depending on their rates of ruminal degradation. [Copyright &y& Elsevier]

The fermentation quality of small-bale silage and haylage for feeding to horses in Sweden, and using a conventional high-density hay baler, was investigated in two experiments. Treatments studied were use of additives (inoculants containing lactic acid bacteria and a chemical additive consisting of hexamethylenetetramine, sodium nitrate, sodium benzoate and sodium propionate), the influence of dry-matter (DM) content of wilted herbage and the effect of number of stretch film layers on fermentation pattern and aerobic stability. All silages and haylages were made from predominantly Timothy swards and were well fermented as indicated by low levels of ammonia and butyric acid. Values of pH were higher and concentrations of organic acids were lower in haylages than in the silages. This was not considered to be indicative of a poor fermentation in the haylage but of a restricted fermentation due to the high DM content of the herbage. The additives enhanced aerobic storage stability because of inhibition of mould growth. The only statistically significant effect of varying the number of stretch film layers was a higher content of CO2 inside the bales when ten layers of stretch film were applied compared with six layers. [ABSTRACT FROM AUTHOR]

The effect of two fish oil (FO) types, FOa (n-3-eicosapentanoic acid (EPA), 18.1%; n-3-docosahexanoic acid (DHA), 11.9%) and FOb (EPA, 5.4%; DHA, 7.5%) and quantity (0, 12.5, 25, 50, 75, 100 and 125 mg FO) on rumen fermentation patterns was evaluated with 24 and 48 h batch in vitro incubations and compared with fermentation shifts induced by soybean oil (SO). The 48 h incubation was essentially a batch culture as it was re-inoculated with rumen fluid, buffer and hay after 24 h. Shifts in rumen fermentation pattern were only observed during the second step of the 48 h incubation for the three oils. The inhibition of rumen methane (CH4) production was influenced by both oil (FOa>SO>FOb) and concentration, although amounts higher than 75 or 25 mg for FOa and FOb, respectively, did not decrease further CH4 production. A maximal CH4 inhibition of 80% was observed. CH4 inhibition seems proportional to the relative amount of polyunsaturated fatty acids (PUFA) and their rate of lipolysis. Lower CH4 production was accompanied by increased propionate and reduced acetate production. SO supplementation was associated with lower net VFA productions (−17%), whereas none of the amounts of FO reduced VFA production. In vivo effects of rumen FOa injection (18 ml, twice daily at 1 h after feeding) on rumen fermentation and NDF digestibility were studied in a cross-over trial with four rumen canulated wethers, offered a hay/concentrate (65/35, w/w) diet, at their maintenance energy requirements. In vivo FOa injection did not alter faecal NDF digestibility (48.5±4.5% versus 46.5±8.2% for control and FOa, respectively, P>0.05), despite a lower 48 h rumen in sacco degradability (57.5±3.3% versus 51.6±5.8%, P<0.05). FOa-induced higher rumen propionate concentrations (211.8±18.0 versus 262.7±20.8 mmol/mol total VFA, P<0.05), suggesting a depression of rumen methanogenesis, confirmed during simultaneous in vitro incubations (344.2±43.4 versus 287.7±36.6 mmol/mol total VFA, P<0.05). Reduced biohydrogenation of FO PUFA, resulting in rumen accumulation of unesterified EPA and DHA might be nutritionally and ecologically relevant in terms of an increased post-ruminal supply of these PUFA for incorporation into animal products and through reduced rumen methanogenesis, the latter representing both an energy loss for the animal and an important greenhouse gas. [Copyright &y& Elsevier]

Simple Summary: Ruminant husbandry is one the largest contributors to greenhouse gas emissions from the agriculture sector, particularly of methane gas, which is a byproduct of the anaerobic fermentation of structural and non-structural carbohydrates in the rumen. Increasing the efficiency of production systems and decreasing its environmental burden is a global commitment, thus methane mitigation is a strategy in which to reach these goals by rechanneling metabolic hydrogen (H2) into volatile fatty acids (VFA) to reduce the loss of energy as methane in the rumen, which ranges from 2% (grain rations) to 12% (poor-quality forage rations) of gross energy intake. A strategy to achieve that goal may be through the manipulation of rumen fermentation with natural compounds such as chitosan. In this review, we describe the effects of chitosan on feed intake and rumen fermentation, and present some results on methanogenesis. The main compounds with antimethanogenic properties are the secondary metabolites, which are generally classified into five main groups: saponins, tannins, essential oils, organosulfurized compounds, and flavonoids. Novel compounds of interest include chitosan obtained by the deacetylation of chitin, with beneficial properties such as biocompatibility, biodegradability, non-toxicity, and chelation of metal ions. This compound has shown its potential to modify the rumen microbiome, improve nitrogen (N) metabolism, and mitigate enteric methane (CH4) under some circumstances. Further evaluations in vivo are necessary at different doses in ruminant species as well as the economic evaluation of its incorporation in practical rations. Livestock production is a main source of anthropogenic greenhouse gases (GHG). The main gases are CH4 with a global warming potential (GWP) 25 times and nitrous oxide (N2O) with a GWP 298 times, that of carbon dioxide (CO2) arising from enteric fermentation or from manure management, respectively. In fact, CH4 is the second most important GHG emitted globally. This current scenario has increased the concerns about global warming and encouraged the development of intensive research on different natural compounds to be used as feed additives in ruminant rations and modify the rumen ecosystem, fermentation pattern, and mitigate enteric CH4. The compounds most studied are the secondary metabolites of plants, which include a vast array of chemical substances like polyphenols and saponins that are present in plant tissues of different species, but the results are not consistent, and the extraction cost has constrained their utilization in practical animal feeding. Other new compounds of interest include polysaccharide biopolymers such as chitosan, mainly obtained as a marine co-product. As with other compounds, the effect of chitosan on the rumen microbial population depends on the source, purity, dose, process of extraction, and storage. In addition, it is important to identify compounds without adverse effects on rumen fermentation. The present review is aimed at providing information about chitosan for dietary manipulation to be considered for future studies to mitigate enteric methane and reduce the environmental impact of GHGs arising from livestock production systems. Chitosan is a promising agent with methane mitigating effects, but further research is required with in vivo models to establish effective daily doses without any detrimental effect to the animal and consider its addition in practical rations as well as the economic cost of methane mitigation. [ABSTRACT FROM AUTHOR]

Butanol has been regarded as an important bulk chemical and advanced biofuel; however, large scaling butanol production by solventogenic Clostridium sp. is still not economically feasible due to the high cost of substrates, low butanol titer and yield caused by the toxicity of butanol and formation of by-products. Renewed interests in biobutanol as biofuel and rapid development in genetic tools have spurred technological advances to strain modifications. Comprehensive reviews regarding these aspects have been reported elsewhere in detail. Meanwhile, more wild type butanol producers with unique properties were also isolated and characterized. However, few reviews addressed these discoveries of novel wild type solventogenic Clostridium sp. strains. Accordingly, this review aims to comprehensively summarize the most recent advances on wild type butanol producers in terms of fermentation patterns, substrate utilization et al. Future perspectives using these native ones as chassis for genetic modification were also discussed. [ABSTRACT FROM AUTHOR]