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PubMed1995

Effect of malate on in vitro mixed ruminal microorganism fermentation.

The objective of this study was to evaluate the effects of different concentrations of DL-malate (disodium salt) on the in vitro mixed ruminal microorganism fermentation of soluble starch or cracked corn. Ruminal fluid was collected from a steer fed 6.8 kg of forage and 2.3 kg of concentrate supplement once daily, and mixed ruminal microorganisms were incubated in anaerobic media (40 mL) that contained 20% (vol/vol) ruminal fluid in batch culture for 24 h at 39 degrees C. Malate was added to the incubation bottles (n = 4) to achieve final concentrations of 0, 4, 8, and 12 mM. When mixed ruminal microorganisms were incubated with only DL-malate as the substrate, final pH numerically increased, propionate and total VFA concentrations increased (P < .05), and the acetate:propionate ratio decreased (P < .05) as the concentration of DL-malate increased from 0 to 12 mM. Fermentation of cracked corn in the presence of 8 or 12 mM DL-malate resulted in an increase (P < .05) in final pH and propionate concentration. Total VFA tended to increase (P < .21), whereas final concentrations of L-lactate numerically decreased. In the case of soluble starch, 8 and 12 mM DL-malate caused a decrease (P < .05) in methane concentration. When only ruminal fluid (no added anaerobic medium) was used as the inoculum rather than 20% ruminal fluid medium, similar results for final pH, propionate, L-lactate, and total VFA were observed for soluble starch and corn incubations treated with DL-malate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Comparative in-vitro activity of ciprofloxacin against non-fermenters.

The in-vitro activity of ciprofloxacin, a quinolone-carboxylic acid derivative, was compared with those of carbenicillin, azlocillin, cefsulodin, ceftazidime, tobramycin and amikacin against 187 non-fermenters. Only one of the 131 strains of Pseudomonas spp. was not inhibited by 1 mg/l of ciprofloxacin, while these isolates appeared highly resistant to carbenicillin, azlocillin and cefsulodin. Ciprofloxacin was also the best agent against Flavobacterium, Alcaligenes faecalis and Acinetobacter calcoaceticus with MIC90's respectively of 0.5, 4 and 8 mg/l. This new compound appeared bactericidal, and we found a small or no inoculum effect with ciprofloxacin.

Anti-Bacterial Agents↗
PubMed1986

Effects of potassium buffers on feed intake in lactating dairy cows and on rumen fermentation in vivo and in vitro.

Twenty-four Holstein cows were used to compare acceptance of concentrates and complete rations containing 1) no buffer, 2) 1.8% potassium bicarbonate, 3) 1.2% potassium carbonate, or 4) 1.5% sodium bicarbonate in the concentrate. When concentrate and a forage blend were offered separately (comparison period 1), concentrate intake did not differ among treatments, but forage blend consumption and complete ration intake was greater with the potassium carbonate ration (comparison period 2). Rumen pH did not differ, but urine pH was higher in cows fed complete rations containing buffers. Cows fed potassium carbonate had higher milk fat percentages than cows fed sodium bicarbonate during the first comparison period and higher than controls during the second comparison period and produced more 3.5% fat-corrected milk and solids-corrected milk than cows fed sodium bicarbonate in both comparison periods. Milk protein percentage was lower in cows fed potassium carbonate diets as compared with those fed sodium bicarbonate diets, but total protein production was similar. In three continuous culture in vitro trials, potassium carbonate maintained fermenter pH comparably to sodium bicarbonate, and total volatile fatty acid and acetate production were similar.

Animals↗
PubMed1990

Effects of hard fats on in vitro and in vivo rumen fermentation, milk production and reproduction in dairy cows.

Adding 0, 5, 15, and 20% of substrate as prilled or unprilled fatty acids [palmitic (47 to 48%), stearic (36 to 37%), and oleic (14%) acids] to an in vitro rumen fermenter had no effect on total VFA production. Acetate:propionate ratio was reduced by fatty acid concentrations of 15 and 20% (prilled and unprilled). In a 4 x 4 Latin square, increasing dietary prilled fatty acids (0, 3, 6, or 9% of DM) decreased DM intake, increased percentage of milk fat, and had no effect on percentage of milk protein. Milk volume and FCM increased with 3% but decreased with 6 and 9% dietary fatty acids. Rumen fluid acetate:propionate decreased with increasing dietary fatty acids. Holstein cows in three herds in Pennsylvania and Friesian cows in an Israeli herd were assigned randomly to receive, from 0 to 110 to 150 d postcalving, diets containing 0 or 2% of DM prilled fat. In Israel, dietary fat increased milk yield, FCM, and fat percentage during the first 90 d postcalving. In Pennsylvania, prilled fat had variable effects on milk composition and little effect on milk yield and FCM. Conception rate was improved in cows consuming rations containing prilled fat: first service, 59.1 versus 42.6%; all services, 59.3 versus 40.7%. The inclusion of prilled fat at 2% of DM in dairy cattle rations had slight effects on rumen fermentation, variable effects on milk yield and composition, and beneficial effects on conception rate.

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↗
PubMed1993

Effect of rabadi fermentation on phytic acid and in vitro digestibility of barley.

Rabadi, an indigenous fermented food, was prepared by mixing cereal flour with buttermilk, allowing it to ferment at 30, 35 and 40 degrees C for 6, 12, 18, 24 and 48 h and cooking the fermented mixture for 0.5 h with continuous stirring. Two types of rabadi were prepared i.e. autoclaved and unautoclaved. In autoclaved type of rabadi cereal flour was mixed with water, autoclaved (0.103 MPa = 15 psi for 15 min), cooled, mixed with buttermilk and fermented. As this type of rabadi was precooked prior to fermentation, hence, the fermented product did not require cooking afterwards, while in unautoclaved rabadi, barley flour and buttermilk were mixed, fermented and then cooked prior to consumption. Phytic acid was reduced drastically at all the temperatures and periods of fermentation in both autoclaved and unautoclaved type of rabadi; greater reduction occurred at higher temperature and duration of fermentation. A significant improvement in the in vitro digestibility of starch and protein was observed; maximum improvement was noticed when fermentation was carried out at 40 degrees C for 48 h in both the types of rabadi. Phytic acid had a significant (P < 0.05) negative correlation with digestibility (in vitro) of proteins and starch of barley flour rabadi.

Animals↗
PubMed2003

In vitro evaluation of the fermentation properties of galactooligosaccharides synthesised by alpha-galactosidase from Lactobacillus reuteri.

Stirred, pH-controlled anaerobic batch cultures were used to evaluate the in vitro utilisation by canine gut microflora of novel alpha-galactooligosaccharides synthesised with an enzyme extract from a canine Lactobacillus reuteri strain. Fructooligosaccharides (FOS), melibiose and raffinose were used as reference carbohydrates for the prebiotic properties of the synthesised oligosaccharide (galactosyl melibiose mixture-GMM). Addition of Lactobacillus acidophilus was used as control for the evaluation of the synbiotic properties of the oligosaccharide with L. reuteri. Populations of predominant gut bacterial groups were monitored over 48 h of batch culture by fluorescent in situ hybridisation, and short-chain fatty acid (SCFA) production was measured. GMM showed a higher increase in bifidobacteria and lactobacilli population number and size as well as a higher decrease in clostridia population number and size compared to the commercial prebiotics (FOS, melibiose, raffinose). This prebiotic effect was further increased by the addition of L. reuteri followed by a change in the SCFA production pattern compared to GMM alone or GMM with L. acidophilus. The observed change in SCFA production was in accordance with the fermentation properties of L. reuteri, suggesting that the novel synbiotic had a significant effect on the canine gut microflora fermentation.

Acetic Acid↗
PubMed1993

In vitro production of short-chain fatty acids by bacterial fermentation of dietary fiber compared with effects of those fibers on hepatic sterol synthesis in rats.

The aim of this study was to determine the effects of fiber feeding on short-chain fatty acid (SCFA) production in laboratory rats and in an in vitro fermentation model using fecal inocula from rats adapted to a high fiber diet. In addition, the effect of fiber intake on endogenous sterol synthesis was evaluated. Twenty male Sprague-Dawley rats were divided into four groups and fed a control or 30% fiber diet (cellulose, pectin or pea fiber) for 4 wk. In vitro fermentation was compared with measurements of cecal SCFA content of fiber-adapted rats. Sterol synthesis in isolated hepatocytes was determined in groups of five to seven rats fed 15% dietary fiber for 4 wk. Cellulose was poorly fermented in both the in vitro and in vivo experiments. Pectin fermentation produced high levels of propionate, whereas pea fiber was associated with notable butyrate production. Adaptation to pectin produced seven times more SCFA in rat cecal contents (515 +/- 78 mumol) in comparison to a fiber-free diet (70.6 +/- 4.9 mumol), with similar results observed in vitro. Sterol synthesis in hepatocytes of rats fed pectin was significantly greater than in those of control or cellulose-fed rats. Despite significantly higher rates of SCFA production in pectin-fed rats, cholesterol synthesis was not inhibited, suggesting that SCFA are not the cholesterol-lowering factor of highly fermentable fiber sources.

Acetates↗
PubMed2005

Proteolysis, fermentation efficiency, and in vitro ruminal digestion of peanut stover ensiled with raw or heated corn.

Peanut stover (PS) is similar to full-bloom alfalfa hay in chemical composition. The objective of this study was to assess the effect of adding raw or heated corn meal to PS at ensiling on silage N components, fermentation acids, and digestion by ruminal microorganisms. The PS was collected after harvesting of peanuts and ensiled immediately without and with addition of raw or heated corn meal (100 g/kg of fresh weight). Corn was added to PS so that the initial mixture would contain adequate dry matter (DM) (approximately 30%) and additional nonfiber carbohydrate to enhance silage fermentation. After 8 wk of silo fermentation, corn-treated silages contained less structural carbohydrates but more non-fiber carbohydrates compared with the untreated control. A shift from hemicellulose to nonfiber carbohydrate use during silage fermentation was evident by corn treatment. Additional corn at ensiling resulted in silage N with less water-soluble N, protein N, nonprotein N, nonprotein nonammonia N (peptides plus amino acids), and ammonia N. Based on changes in soluble nonprotein N before and after ensiling, the amount of proteolysis was approximately 66% for control silage and was nearly 40% lower in response to corn treatment. Adding corn increased silage lactic acid, but both acetic and propionic acids decreased. These changes were reflected in the lower pH and higher fermentation efficiency with corn-treated silages. More DM was digested and greater amounts of volatile fatty acids, except for branched-chain acids, were produced in vitro by ruminal microorganisms with corn-treated silages. In addition, incubations with silage treated with heated corn contained higher concentrations of acetic and propionic acids compared with raw corn. In vitro ammonia accumulation per unit of DM digested was lower for corn treatments than the control, and for heated corn vs. raw corn-treated silage. These results indicate that supplementation of either raw or heated corn on PS at ensiling could minimize proteolysis and improve fermentation efficiency. Advantages from using heated vs. raw corn could extend beyond silage fermentation and include rumen microbial fermentation.

Acetic Acid↗
PubMed2006

Bioaccessibility of beta-carotene, lutein, and lycopene from fruits and vegetables.

Epidemiological studies have consistently demonstrated that there is an association between carotenoid-rich food intakes with a low incidence in chronic diseases. Nevertheless, there is not an association between the intake of total dietary carotenoids and chronic health incidence in the European population, probably because of different carotenoid food sources and bioavailability. The objective of this study was to evaluate the small and large intestine bioaccessibilities of major dietary carotenoids from fruits and vegetables in a common diet. A bioaccessibility model that includes enzymatic digestion and in vitro colonic fermentation was employed. Lutein presented greater small intestine bioaccessibility (79%) than beta-carotene (27%) or lycopene (40%). With regard to large intestine bioaccessibility, similar amounts of lycopene and beta-carotene were released from the food matrix (57%), whereas small amounts of lutein (17%) were released. These results suggest that 91% of the beta-carotene, lutein, and lycopene contained in fruits and vegetables is available in the gut during the entire digestion process. Colonic fermentation is shown to be important for carotenoid availability in the gut.

Animals↗
PubMed1992

[In vitro simulation of rabbit cecal fermentation in a semi- continuous flow fermentor. I. Role of food substrate pretreatment].

A Rusitec semi-continuous flow fermentor was used to study the influence of enzyme pretreatment of food substrates on the fermentation profile over a 2-week period following inoculation with rabbit caecal contents. Three types of substrate were examined: 1) homogenized commercial rabbit feed; 2) the solid remains of this feed after digestion with alpha-amylase for 24 h; and 3) substrate 2 digested for 4 h with pepsin (double enzyme treatment). One of a pair of nylon pouches containing 15 g substrate was replaced each day, thus producing a uniform 48-h fermentation. Fermentation of the untreated feed (1) for 5-6 days produced a fermentation profile quite different from that obtained in vivo in the rabbit caecum: propionic acid accounted for over 35% of total volatile fatty acid (VFA), and butyric acid for about 15%. Amylase digestion (2) gave a stable ferment profile closer to the in vivo profile, except that propionic and butyric acids were similar at 15% of total VFA. Digestion with both amylase and pepsin (3) produced a stable fermentation profile very close to the in vivo profile: C2 > 60%, C3 < 11% and 17% < C4 < 21%. The rate at which membrane constituents (acid detergent fibre, ADF) were lost in 48 h was similar to the digestibility coefficient measured in vivo by others for the same basic feed. Lastly, there was a high percentage (about 5%) of volatile C5 fatty acids; this could be due to the discontinuous fermentor input of one pouch per 24 h. Thus, feed pretreated with both amylase and pepsin simulates, in vitro, rabbit caecal fermentation in a semi-continuous Rusitec type fermentor.

Animal Feed↗
PubMed1998

Flow cytometric analyses of the specific activation of peripheral blood mononuclear cells from healthy donors after in vitro stimulation with a fermented mistletoe extract and mistletoe lectins.

Immunostimulatory properties of mistletoe extracts derived from Viscum album L. (VAL) are well described, demonstrating activation especially of T, T-helper cells and monocytes/macrophages. In order to characterise in detail the communication between different cell populations, we studied mistletoe-induced expression of co-stimulatory signals and their ligands by flow cytometry. Peripheral blood mononuclear cells (PBMC) from 15 healthy controls were incubated for 7 days with a fermented VAL extract. VAL significantly upregulated the expression of the co-stimulatory molecule B7.1 (CD80) on monocytes/macrophages, but not B7.2 (CD86). No significant changes in the expression of either molecules on B cells could be found, suggesting that only monocytes/macrophages act as antigen presenting cells (APCs) in this in vitro system. Purified mistletoe lectins, components of most VAL extracts were also analysed, but did not induce similar responses of monocytes/macrophages. The receptor for B7 molecules, CD28, but not CTLA-4 (CD152), was also found to be significantly enhanced on CD4+ cells after VAL simulation. There was no evidence for activation of a B cell response via the CD40/CD40L pathway. Our data support the concept that stimulation by VAL extracts induces a specific T-helper cell reaction with monocytes/macrophages acting as APCs and purified lectins do not exert the same effects.

Adult↗
PubMed1995

Kinetics of hydration and functional specific gravity of fibrous feed by-products.

Five studies were conducted to evaluate the kinetics of digestion, hydration, and functional specific gravity (FSG) of various feed by-products (FBP) in vitro. The water-holding capacity (WHC) of alfalfa and orchardgrass (1.428 and 1.005 g/g of insoluble DM [IDM], respectively) was higher (P < .05) than the WHC of FBP, which ranged from .175 for distillers grains to .481 g/g of IDM for brewers grains pellets. Rate of hydration was the highest in brewers grains pellets and beet pulp (.215 and .252 min-1, respectively), whereas the lowest hydration rates were observed in orchardgrass, corn cob pellets, and soyhulls (.055 to .066 min-1). Loss of associated gasses from feed particles fermented in vitro increased (P < .05) their FSG when the contents of incubation tubes were transferred to pycnometers, compared with that when the incubation was carried out directly in the pycnometers (1.17 vs 1.13) to determine their FSG. Gas produced during fermentation delayed the increase in the FSG of all sources of brewers grains and beet pulp, corn gluten feed, distillers grains, orchardgrass, alfalfa, and wheat middlings but not of corn cob pellets, cottonseed hulls, and soyhulls. Averaged across hours of incubation, the FSG of FBP (except beet pulp) was either higher (P < .05) or tended to be higher than that of alfalfa and orchardgrass. Particle size of FBP did not influence FSG during fermentation in vitro. The WHC and FSG of feeds may be helpful in predicting the rate of passage of feeds through the rumen.

Animal Feed↗
PubMed1976

Fermentation tubes for in vitro digestion of forages.

During in vitro digestion of forages by rumen microorganisms in polycarbonate centrifuge tubes, forage particles formed dense mats which were raised above the level of media by entrapped gas. This did not occur with polyethylene centrifuge tubes. In vitro organic matter digestion was higher in polyethylene than in poly-carbonate tubes. Vacuum infiltration of water into samples prior to inoculation increased in vitro digestion with both types of tubes but to a greater extent with samples of high than of low digestion. Regression analysis of in vivo digestibility on in vitro digestion showed that the lowest residual standard deviation was with polyethylene tubes and vacuum infiltration, but omission of vacuum infiltration gave satisfactory results.

Animal Feed↗
PubMed2001

Metabolic and functional properties of lactic acid bacteria in the gastro-intestinal ecosystem: a comparative in vitro study between bacteria of intestinal and fermented food origin.

Metabolic and functional properties of probiotic lactic acid bacteria (LAB) in the human gastro-intestinal ecosystem may be related to certain beneficial health effects. In this study, lactobacilli of either intestinal or fermented food origin were compared in their capability to survive low pH and bile, in their metabolic activity in the presence of bile salts and mucins, as well as in their potential to attach to enterocyte-like CaCO-2 cells. Food fermenting bacteria especially strains of the species Lactobacillus plantarum showed high tolerance to the consecutive exposure to hydrochloric acid (pH 1.5-2.5) and cholic acid (10 mM). Growth in and deconjugation of glycocholic (5 mM) and taurocholic acids (5 mM), as demonstrated for all lactobacilli of intestinal origin, was detected for food fermenting strains of the species L. plantarum, but not L. paracasei and L. sakei. Degradation of mucins was not observed for lactobacilli. Adhesion to the intestinal epithelial cell line CaCO-2 was demonstrated for several food fermenting bacterial strains in vitro. Soluble factors in the spent culture supernatants from intestinal and fermented food lactobacilli but not staphylococci cross reacted and synergized with cell wall components to promote adhesion to CaCO-2 cells. A competitive role of fecal bacteria on the adhesion of lactobacilli to CaCO-2 cells was demonstrated. In conclusion we have shown that metabolic and functional properties of intestinal lactobacilli are also found in certain bacteria of fermented food origin.

Bacterial Adhesion↗
PubMed1993

Fermentation of dietary fibre by human colonic bacteria: disappearance of, short-chain fatty acid production from, and potential water-holding capacity of, various substrates.

Several dietary fibre-rich substrates were fermented in vitro with human colonic bacteria obtained from each of three adult male subjects to assess the extent of substrate fermentation short-chain fatty acid (SCFA) production, and the potential effect of fermented residues on faecal bulk. Substrates tested were two varieties of oat hull fibre, gum arabic, carboxymethylcellulose (CMC), soy fibre, psyllium, and six blends containing oat fibre, gum arabic, and CMC in various proportions. All substrates contained greater than 900 g/kg of total dietary fibre except for CMC (816 g) and soy fibre (778 g). In vitro organic matter disappearance during fermentation was greatest for gum arabic (69.5%), intermediate for soy fibre (56.4%), and less than 20% for the two oat fibres, CMC, and psyllium. Averaged across substrates, acetate, propionate, and butyrate were produced in the molar proportion of 64:24:12. Potential water-holding capacity (PWHC) of substrates, a measure of faecal bulking potential, was greatest for CMC (13.5 g H2O/g substrate) and lowest for gum arabic (1.92 g) and soy fibre (1.71 g). Organic matter disappearance and SCFA production of blends were directly proportional to their gum arabic content. Blend PWHC was proportional to CMC content. In vitro procedures are useful in predicting the actions of fibre blends formulated to produce desirable effects in vivo.

Adult↗