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PubMed1988

Influence of DL-methionine supplementation on growth, ruminal fermentation and dilution rates in heifers.

A 3 X 3 replicated Latin square design was used to evaluate three isonitrogenous supplements designed to supply 250 g crude protein (CP) daily. Measurements included in situ dry matter (DM) and neutral detergent fiber (NDF) fermentation and ruminal dilution rates. Supplements contained beet pulp plus DL-methionine and urea (MET), ammonium sulfate and urea (U) or soybean meal (SBM). Six mature, ruminally cannulated crossbred beef cows were individually fed supplement and a mixture (63% NDF and 6.1% CP) of chopped 75% grass hay and 25% barley straw in ad libitum. Fermentation rate of DM was increased (P less than .05) by 30% with MET in comparison to SBM or U (9.54 vs 7.28% and 7.74%/h for MET, SBM and U, respectively). Even though MET improved fermentation rate by 30%, particle dilution rate was more important in affecting ruminal digestibility than fermentation rate. Two 90-d heifer growth trials were conducted to evaluate similar supplements. Supplements similar to those used in the in situ trial were mixed with roughage to provide a complete diet balanced for .3 kg daily gain. Heifers consumed 112% of the National Research Council CP requirement. Weight gain, intake and feed conversion were similar (P greater than .10) for all treatments. In heifer trial 2, 90% of the National Research Council CP requirement was fed. The heifers supplemented with MET and SBM had faster (P less than .05) weight gains than heifers receiving U. These studies show that feeding DL-methionine with urea, as compared with feeding an isonitrogenous supplement containing SBM, increased the fermentation rate of DM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Sorbose fermentation in relation to acquisition and maintenance of enterotoxin plasmids in Escherichia coli.

Previous studies have shown that the majority of enterotoxigenic Escherichia coli (ETEC) strains isolated from humans failed to ferment sorbose. In an attempt to demonstrate if this phenomenon was due to enterotoxin (Ent) plasmid instability in sorbose fermenting strains, recipient E. coli strains were used in conjugation experiments with three donor Ent plasmids. No difference in the ability to uptake the Ent plasmid was shown between sorbose fermenting and non-fermenting recipient strains. In addition, no difference was seen in the stability of the Ent plasmids in recipient strains of each biotype. These results suggest that in-vivo selection may play a role in the predominant isolation of non-sorbose fermenting ETEC strains.

Drug Resistance, Microbial↗
PubMed1993

The role of carbohydrate fermentation in colon cancer prevention.

Diet is an important factor in the development of colonic cancer. Fibre has been shown to decrease this risk. Part of this protective effect is probably mediated by colonic fermentation. About 10% of starch in the normal diet escapes digestion and absorption in the small bowel, and is therefore called resistant starch. This is a considerably larger source of fermentable substrate than fibre in the diet and could thus contribute significantly to the prevention of this malignancy. Short chain fatty acids, produced during fermentation, reduce colonic pH, affecting the intraluminal concentration of the putative co-carcinogenic secondary bile acids by precipitation, and by inhibition of their enzymatic formation from primary bile acids. The role of secondary bile acids in promoting colonic carcinogenesis is probably mediated by their cytotoxic effect on colonic mucosa, leading to a compensatory increase in proliferation. A hyper-proliferative mucosa, having an enhanced sensitivity to mutagenic substances, is associated with an increased risk of colorectal cancer. Butyrate, one of the short chain fatty acids, could be significant, as it has anti-neoplastic properties in vitro and in vivo. We conclude that fermentation is probably the key factor in the protective effect of fibre on colon carcinogenesis. Furthermore, consumption of resistant starch seems to be another way of stimulating fermentation.

Bile Acids and Salts↗
PubMed1995

Colonic fermentation of complex dietary carbohydrates in short-bowel patients. No association with hydrogen excretion and fecal and plasma short-chain fatty acids.

BACKGROUND: The colonic degradation of carbohydrates (fermentation) to short-chain fatty acids (SCFAs) appears to have major impacts on colonocyte function, sodium and water absorption, and large-bowel energy salvation, but how to quantify the in vivo fermentation in man is still debatable. METHODS: Indicators of colonic fermentation, fecal and plasma SCFAs and breath hydrogen (H2), were measured in 10 short-bowel patients (mean +/- SE; 106 +/- 21 cm) with totally preserved large bowels who were on a 60% high-carbohydrate, 20% low-fat diet, compared with the reversed isocaloric 20% low-carbohydrate, 60% high-fat diet. This human model showed large differences in large-bowel fermentation, as excretions of calories were reduced (40%; 485 +/- 151 kcal/day) and excretions of carbohydrates were unchanged and low with the high-carbohydrate diet as compared with the low-carbohydrate diet, in contrast to unchanged calorie excretion in short-bowel patients with no colonic function. RESULTS: Fecal concentrations of SCFAs did not change when the diet was changed from the high content to the low content of carbohydrates (82 +/- 11 mmol/l and 79 +/- 9 mmol/l, respectively). The ratio of acetate in feces increased (from 48 +/- 4% to 54 +/- 3%; p = 0.01) on the high-carbohydrate diet, whereas the percentage of the other SCFAs decreased proportionally. Plasma SCFAs 2 h and 6 h after breakfast were also identical when comparing the two dietary regimens. Nor were the peak H2 breath excretion and the area under the H2 excretion-versus-time curve increased by the threefold increase in the intake of dietary carbohydrates. CONCLUSIONS: Fecal and plasma SCFAs and breath H2 excretion are of limited value in the evaluation of even large differences in colonic fermentation of complex dietary carbohydrates.

Adult↗
PubMed1994

Immobilized cells in meat fermentation.

The immobilization of microbial cells can contribute to fermented meat technology at two basic levels. First, the solid/semisolid nature (low available water) of the substrate restricts the mobility of cells and results in spatial organizations based on "natural immobilization" within the fermentation matrix. The microniches formed influence the fermentation biochemistry through mass transfer limitations and the subsequent development and activity of the microflora. This form of immobilization controls the nature of competition between subpopulations within the microflora and ultimately exerts an effect on the ecological competence (ability to survive and compete) of the various cultures present. Second, immobilized cell technology (ICT) can be used to enhance the ecological competence of starter cultures added to initiate the fermentation. Immobilization matrices such as alginate can provide microniches or microenvironments that protect the culture during freezing or lyophilization, during subsequent rehydration, and when in competition with indigenous microflora. The regulated release of cells from the microenvironments can also contribute to competitive ability. The regulation of both immobilization processes can result in enhanced fermentation activity.

Fermentation↗
PubMed2002

The effect of Lactobacillus buchneri 40788 on the fermentation and aerobic stability of high moisture corn in laboratory silos.

The production of antifungal compounds during fermentation could be a useful mechanism to improve the aerobic stability of fermented feeds when they are exposed to air. High moisture corn (26% moisture) was ground and inoculated with various amounts of Lactobacillus buchneri 40788, a heterolactic acid bacteria, and ensiled in laboratory silos. Inoculation with L. buchneri 40788 from 1 x 10(5) to 1 x 10(6) cfu/g of corn had minor effects on the end products of fermentation during the early stage of ensiling (< or = 14 d). However, after 49, 92, and 166 d of ensiling, increasing the application rate of L. buchneri 40788 applied to corn increased the concentration of acetic acid when compared to untreated corn. Addition of L. buchneri 40788 had few other effects on the end products of fermentation. Dry matter recovery and aerobic stability were measured after 92 and 166 d of ensiling. At these times, dry matter recovery was not different among treatments, and numbers of yeasts and molds tended to decrease as the application rate of L. buchneri 40788 increased. Aerobic stability (number of h prior to a 2 degrees C rise in temperature after exposure to air) was markedly improved by the addition > or = 5 x 10(5) cfu/g of L. buchneri 40788. Combining L. buchneri 40788 with L. plantarum did not impart better aerobic stability than when L. buchneri 40788 was applied alone to corn. Addition of L. buchneri 40788 did not affect the rate of fermentation in high moisture corn, but after prolonged storage higher application rates increased production of acetic acid and markedly improved aerobic stability.

Acetic Acid↗
PubMed2003

The impact of fermentation and in vitro digestion on the formation of angiotensin-I-converting enzyme inhibitory activity from pea and whey protein.

Pea and whey protein were fermented by Lactobacillus helveticus and Saccharomyces cerevisiae in monoculture and in combination at 28 and 37 degrees C in order to release angiotensin-I-converting enzyme (ACE) inhibitory peptides. The fermentation products were subjected to in vitro gastrointestinal digestion, and the digests of nonfermented samples served as controls. After fermentation, the ACE inhibitory activity (%) increased by 18 to 30% for all treatments, except for the fermentations of whey protein with Saccharomyces cerevisiae at 28 degrees C, where no significant change was observed. After digestion, however, both fermented and nonfermented samples reached maximum ACE inhibitory activity. The whey digests tended to have lower (50%) inhibitory concentrations (IC50; 0.14 to 0.07 mg/ml), hence, higher ACE inhibitory activity, than the pea digests (0.23 to 0.11 mg/ml). The nonfermented whey protein digest showed the highest ACE inhibitory activity of all. For pea protein, the nonfermented sample had the lowest IC50 value. These results suggest that in vitro gastrointestinal digestion was the predominant factor controlling the formation of ACE inhibitory activity, hence, indicating its importance in the bioavailability of ACE inhibitory peptides.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2003

Effect of storage method on fermentation characteristics, aerobic stability, and forage intake of tropical grasses ensiled in round bales.

The effect of storage method and length of the fermentation period were evaluated to determine fermentation characteristics, aerobic stability, and forage intake of native tropical grasses ensiled in round bales. Bales were stored under shade or under direct sunlight and sampled after seven periods of ensiling (0, 1, 4, 11, 25, 53, and 111 d). For the aerobic stability and nutritive value studies, three bales were opened from each storage method after 53 and 111 d, exposed to air, and fed to heifers for voluntary consumption. The storage method did not affect fermentation characteristics, however, during aerobic exposure, silage storage under shade resulted in less deterioration as evidenced by lower pH, temperature, and microbial populations. Also, the shorter length of fermentation (53 d) resulted in lower pH and temperature and enhanced aerobic stability. The combination of silage storage under shade and short length of fermentation resulted in the most stable silages and did not improve the nutritive value of native tropical grasses ensiled in large round bales as evidenced by similar forage intake.

Aerobiosis↗
PubMed2004

Hydrolysis of lactose in whey permeate for subsequent fermentation to ethanol.

Fermentation of lactose in whey permeate directly into ethanol has had only limited commercial success, as the yields and alcohol tolerances of the organisms capable of directly fermenting lactose are low. This study proposes an alternative strategy: treat the permeate with acid to liberate monomeric sugars that are readily fermented into ethanol. We identified optimum hydrolysis conditions that yield mostly monomeric sugars and limit formation of fermentation inhibitors such as hydroxymethyl furfural by caramelization reactions. Both lactose solutions and commercial whey permeates were hydrolyzed using inorganic acids and carbonic acid. In all cases, more glucose was consumed by secondary reactions than galactose. Galactose was recovered in approximately stoichiometric proportions. Whey permeate has substantial buffering capacity-even at high partial pressures (>5500 kPa[g]), carbon dioxide had little effect on the pH in whey permeate solutions. The elevated temperatures required for hydrolysis with CO2-generated inhibitory compounds through caramelization reactions. For these reasons, carbon dioxide was not a feasible acidulant. With mineral acids reversion reactions dominated, resulting in a stable amount of glucose released. However, the Maillard browning reactions also appeared to be involved. By applying Hammet's acidity function, kinetic data from all experiments were described by a single line. With concentrated inorganic acids, low reaction temperatures allowed lactose hydrolysis with minimal by-product formation and generated a hexose-rich solution amenable to fermentation.

Animals↗
PubMed2006

Effect of total mixed ration composition on fermentation and efficiency of ruminal microbial crude protein synthesis in vitro.

The goal of this study was to identify dietary factors that affect fermentation and efficiency of microbial crude protein (CP(M)) synthesis in the rumen in vitro. We used 16 total mixed, dairy cow rations with known digestibilities that varied in ingredient composition and nutrient content. Each ration was incubated in a Rusitec (n = 3) for 15 d, and fermentation of different fractions was assessed. Observed extents of fermentation in 24 h were 35 to 47% for organic matter, 25 to 60% for crude protein, 3 to 28% for neutral detergent fiber, and 31 to 45% for gross energy. Organic matter fermentation depended on the content of crude protein and neutral detergent fiber in the ration. We studied net synthesis of CP(M) using an 15N dilution technique and found that 7 d of continuous 15N application are needed to achieve an 15N enrichment plateau in the N of isolated microbes in this type of study. The efficiency of CP(M) synthesis was 141 to 286 g/kg of fermented organic matter or 4.9 to 11.1 g/MJ of metabolizable energy, and these ranges agree with those found in the literature. Multiple regressions to predict the efficiency of CP(M) synthesis by diet data showed that crude protein was the only dietary chemical fraction that had a significant effect. Fat content and the inclusion rate of corn silage in the ration also tended to improve efficiency. We suggest that microbial need for preformed amino acids may explain the crude protein effect. A large part of the variation in efficiency of microbial activity still remains unexplained.

Animal Feed↗
PubMed1975

Fungal growth and acid production during fermentation and refermentation of organic acid treated corn silages.

Chopped corn (35% dry matter) treated with either propionic, formic, 60% propionic plus 40% formic, or 80% propionic plus 20% acetic acids at 0, .5, 1, and 2%, was placed in polyethylene bags inside metal drums, and evacuated. During fermentation silages were sampled and temperatures determined. On day 40 of fermentation silages were placed in open containers at 25 C and were sampled during refermentation. All samples were analyzed for volatile and lactic acids, pH, and number and type of fungi. Lactate fermentation was totally inhibited at 2% addition of all acids, but formic acid was more effective than propionic acid at .5 and 1%. Acerate production was equally depressed by both propionic and formic additions. Heating, growth of fungi, and days until spoilage were delayed by all acid additions during refermentation, with propionic more effectivethan formic. The large increases in lactate and acetate of treated silages during refermentation reflect a protection of soluble sugars during fermentation and subsequent use by microbes after exposure to air. Silages treated with more than 1%propionic (as propionic or a mixture) did not increase in fungal colonies during refermentation. At initiation of fermentation yeasts werehigher than other fungi but decreases by day 40. During refermentation, yeasts again grew. Geotrichum comprised 35% on day 40 of refermentation but was lower at other times. Aspergillus proliferated during refermentation and few Penicillium were detected.

Acetates↗
PubMed1980

Chemical changes in bovine colostrum preserved with formalin or by fermentation.

Fresh bovine colstrum from second and third milkings postpartum was inoculated with either a yogurt culture or Streptococcus lactis or preserved with .1% formalin in two separate experiments. There was a rapid decrease in pH of the fermented samples which corresponded to decreased lactose concentrations and increased lactate and titratable acidity. Titratable acidity in the fermented colostrums increased further after 10 days from the production of volatile fatty acids, but pH did not decrease. The pH of the yogurt fermentations in Experiment 2 decreased to 3.8, and the continued increase in titratable acidity was from lactic acid rather than volatile fatty acids. The lowest pH of all other fermentations was 4.1. The extent of metabolism of the formalin-preserved colostrum was much less than for the colostrum fermented by either culture.

Animals↗
PubMed1984

Changes of bacterial numbers and carbohydrate fermenting groups during in vitro rumen incubations with feedstuff materials.

Short in vitro incubations of mixed ruminal bacteria with feedstuff materials were conducted. In each series of experiments, the rumen bacterial population was divided into equal portions. One portion was washed anaerobically by centrifugation in a mineral buffer prior to initiation of incubation, whereas the other portion was not washed. Changes of carbohydrate group composition of the populations, of bacterial cell composition, and of incubation fluid characteristics were monitored over 24 h. Washing the bacterial inoculum did not affect adversely the ensuing feed fermentation and resulted in lower background carbohydrates and fermentation acids. Unwashed bacterial incubations had a greater tendency to produce more lactate. When the feedstuff substrate contained more soluble nutrients, the microbial population exhibited batch culture type growth, and bacteria fermenting soluble carbohydrate predominated. When alfalfa hay was the sole substrate, a more balanced fermentation resulted with respect to both carbohydrate group composition and fermentation acid production. Implications of these findings in relation to use of in vitro methods to estimate digestibility of feedstuff are addressed.

Ammonia↗
PubMed1987

Alteration of fermentation in continuous culture of mixed rumen bacteria by isolated alfalfa saponins.

Saponins isolated from alfalfa by ethanol extraction and acid hydrolysis were incorporated into protein-free purified diets at 0, .5, 1, 2, and 4% of dietary dry matter to investigate the effect of saponins on fermentation by mixed rumen bacteria maintained in continuous culture. Inoculum was obtained from a lactating dairy cow fed alfalfa hay and a 13% crude protein grain mixture with forage to grain ratios of 33:67, 67:33, or 100:0. Outflow of microbial protein was lower in fermenters fed purified diet containing 1% saponins. Accumulation of ammonia was observed in fermenters fed purified diets containing alfalfa saponins. Total volatile fatty acid production was reduced by addition of isolated alfalfa saponin fraction at .5, 1, 2, and 4% concentrations. Acetate to propionate ratios were reduced from 1.93 in control to 1.37 in fermenters with 1% saponins. Extent of change in fermentation was not proportional to the concentration of added saponins.

Animals↗
PubMed1990

Antimutagenic activity of milk fermented by Streptococcus thermophilus and Lactobacillus bulgaricus.

Antimutagenic activity of acetone or ethylacetate extracts of skim milk fermented by Streptococcus thermophilus, Lactobacillus bulgaricus, or a combination of both the organisms was studied using Salmonella typhimurium (TA 98 and TA 100). Mutagens used were 4-nitroquinoline-N-oxide (a direct-acting mutagen) and 2-aminofluorene (a mutagen requiring S9 activation). Extracts from all fermented milks showed significant (P less than .05) dose response in suppressing the number of revertants caused by NQNO and 2-aminofluorene in both tester strains, whereas extracts from unfermented milk had no effect. Extracts prepared from milk fermented by L. bulgaricus plus S. thermophilus showed significantly (P less than .05) more antimutagenic activity than extracts prepared from milk fermented by S. thermophilus alone. Solvent (acetone vs. ethyl acetate) effect was not significant with 4-nitroquinoline-N-oxide as mutagen. However, in the case of 2-aminofluorene, acetone extracts showed significantly (P less than .05) higher antimutagenic activity. The results of this and related studies strongly indicate that antimutagenic compounds are produced in milk during fermentation by S. thermophilus and L. bulgaricus.

Animals↗
PubMed1994

Effects of extruded soybeans and forage source on fermentation by rumen microorganisms in continuous culture.

Continuous culture fermenters were used to evaluate effects of extrusion of whole soybeans and changes in forage composition of diets on microbial fermentation. Treatments were arranged in a 2 x 4 factorial design with soybeans (raw or extruded) and dietary treatment (ratio of alfalfa hay to corn silage; 82:18, 61:39, 43:57, and 27:73 of dietary forage) as main effects. Soybeans constituted 9.6, 14.4, 19.2, and 23.9% of DM for each of the respective dietary treatments. True digestion of DM, ADF, and NDF was unaffected by processing of soybeans or dietary treatment, but true digestion of OM decreased as concentration of corn silage and soybeans increased. Total VFA concentration was unaffected by source of soybeans or dietary treatments; however, molar concentration of butyrate decreased in fermenters supplied with diets containing extruded soybeans. Degradation of CP was not influenced by soybean source but decreased as the concentration of corn silage and soybeans increased. Bacterial N output decreased, and dietary N flow from the fermenters increased, as concentration of corn silage and soybeans increased. Changes in the ratio of alfalfa hay to corn silage and alteration of dietary soybean concentration affected true OM digestion and dietary CP degradation, but extrusion of whole soybeans had little effect on fermentation.

Animal Feed↗
PubMed1997

Influence of level of concentrate allocation and fermentability of forage fiber on chewing behavior and production of dairy cows.

Nine midlactation dairy cows were offered one of three mixed silage rations with neutral detergent fiber (NDF) that was similar in concentration but different in fermentability. Differences in fermentability were achieved by substituting a high quality alfalfa silage for a low quality alfalfa silage and substituting a combination of ryegrass and timothy silages for a barley silage. In addition, concentrate was allocated at 0.30, 0.82, or 1.37 kg of dry matter/kg of dry matter intake (DMI) from the mixed silage ration. As expected, the NDF content of the mixed silage ration did not differ, although fermentability of NDF increased numerically as forage quality increased. Intake of NDF increased linearly, and DMI tended to increase linearly, as fiber fermentability of the mixed silage ration increased. In addition, cows produced more milk, milk fat, and milk protein and generated more total and milk energy. The calculated concentration of net energy for lactation of the total diet also increased. Results support the concept that NDF quality influences and can be used to predict voluntary feed intake, at least in relatively high producing dairy cows. The DMI increased, and intake of NDF and crude protein declined, as the allocation of concentrate increased. In addition, as concentrate allocation increased, cows spent less time eating and ruminating and more time resting and produced more milk, milk protein, and milk lactose. Cows also generated more total energy and milk energy, although, despite a sharp decrease in the forage proportion of the diet, the calculated energy density of the diet did not differ among concentrate levels. The lack of significant interactions between concentrate level and fiber fermentability for any parameter measured supports the contention that high quality forage is critical to a successful dairy ration, regardless of the proportion of forage in the diet.

Animal Feed↗
PubMed1997

Effects of cellobiose and monensin on in vitro fermentation of organic acids by mixed ruminal bacteria.

The objective of this study was to determine the effects of cellobiose and monensin on the in vitro fermentation of organic acids (L-aspartate, fumarate, and DL-malate) by mixed ruminal bacteria. Ruminal fluid was collected from a steer fed 36.7 kg of forage and 4.5 kg of concentrate supplement once per day. Ruminal fluid was centrifuged to sediment feed particles and protozoa, and the resulting supernatant, which contained bacteria, was added (33%, vol/vol) to anaerobic media (500 ml). Incubations (n = 2) were performed in batch culture at 39 degrees C and sampled at 0, 2, 4, 6, 8, 12, and 24 h. Organic acids were added to achieve a final concentration of 7.5 mM. Cellobiose was added to obtain a final concentration of 5 mM, and monensin dissolved in ethanol was included at concentrations of 0 or 5 ppm. Addition of cellobiose to organic acid fermentations increased the rate of organic acid utilization by the mixed bacterial population. Total concentrations of volatile fatty acids were increased by the addition of cellobiose to all fermentations. A lag period (< or = 8 h) occurred in fermentations that were treated with monensin before organic acids were utilized. Total concentrations of volatile fatty acids were increased, and the acetate to propionate ratio was decreased, by monensin treatment. When cellobiose and monensin were added together, propionate production and organic acid utilization were increased. Both cellobiose and monensin affected the in vitro fermentation of organic acids by mixed ruminal bacteria by providing a carbon and energy source and by influencing electron disposal.

Acetates↗