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PubMed1976

Factors influencing rumen fermentation: effect of hydrogen on formation of propionate.

The effect of hydrogen on fermentation of lactate, pyruvate, fumarate, and succinate by resting rumen microorganisms has been investigated. Under an atmosphere of nitrogen, lactate was fermented to yield acetate as the major product (85 to 100 mole %) and propionate (0 to 17 mole %) and butyrate (0 to 3%) as secondary products. Under hydrogen, there was increased formation of both propionate and total volatile fatty acids. The amount of propionate increased 4 to 8 times and total volatile fatty acids 2.5 to 3.2 times. Propionate formation was proportional to the hydrogen concentration and reached a maximum at a partial pressure of hydrogen of .2 N/m2. With [2-carbon-14] lactate, propionate was formed via the dicarboxylic acid pathway under both nitrogen or hydrogen. Hydrogen did not affect significantly the fermentation of pyruvate or succinate. With fumarate under hydrogen, propionate and total volatile fatty acids increased 6.8 and 2 times while acetate was unchanged. The mechanism by which hydrogen exerts these effects is discussed in relation to the role of methanogenesis in the rumen.

Animals↗

PubMed1995

Development of a mechanistic model for rumen digestion validated using the duodenal flux of amino acids.

A mechanistic model describing rumen digestion is presented. The model consists of 22 compartments for classical nutrients, microbes associated with either solids or fluid, and 8 amino-acid compartments. An empirical approach for volatile fatty acids production is used. Sensitivity and behavioural analysis on several parameters demonstrated the need to improve knowledge concerning certain factors. Model results on general criteria are in good agreement with observed data. Validation on 49 experimental lysine and methionine duodenal fluxes were satisfactory. A comparison between observed and predicted values of LysDi and Metdi on several feedstuffs showed good results. This model is a first step in the building of a rumen model suitable for research and application.

Adenosine Triphosphate↗

PubMed1995

Age dependent variation of caecal contents composition of young rabbits.

In order to study the age dependent variation of caecal contents composition, a young rabbit was slaughtered out of 6 conventional litters at the age of 22; 25; 28; 32; 36; 42 and 56 days. Rabbits were fed a standard diet before and after weaning (at 28 days of age). Daily growth and caecum size were determined. Caecal contents were analyzed for dry matter (DM), pH, crude protein (CP), neutral detergent fibre (NDF), ribonucleic acid (RNA), lactate, ammonia nitrogen and volatile fatty acids (VFA). Between 22 and 25 days of age, a highly significant drop in CP content was found, associated with an increase in NDF content. RNA values tended to decrease with age, but it is striking that the RNA/CP ratio suggests that about 50% of CP is microbial N, very early in the development (22 days). No significant changes of ammonia nitrogen concentration with age were observed, and lactic acid concentration showed some significant changes, suggestive of a decrease after weaning. Total VFA concentration is suggestive of a progressive and significant (P < 0.01) increase reaching a plateau after 42 days (83.7 mmoles/kg). Molar proportions of propionate and butyrate varied significantly (P < 0.001) and inversely with age. Propionate drops by nearly 50% while butyrate proportion doubles between 22 and 56 days of age. The shift from a propionic to a butyric pattern occurs already at day 25. Correlation analysis revealed significant associations between CP-NDF and RNA. The significant negative correlation between pH and daily weight gain reflects the relation caecal pH-animal health. PH was correlated with lactate and VFA concentration.

Aging↗

PubMed2006

In vitro effects of hydrochloric acid and various concentrations of acetic, propionic, butyric, or valeric acids on bioelectric properties of equine gastric squamous mucosa.

OBJECTIVE: To compare the effects of hydrochloric acid (HCl) and various concentrations of volatile fatty acids (VFAs) on tissue bioelectric properties of equine stomach nonglandular (NG) mucosa. SAMPLE POPULATION: Gastric tissues obtained from 48 adult horses. PROCEDURES: NG gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured and electrical resistance (R) and conductance calculated for tissues after addition of HCl and VFAs (5, 10, 20, and 40 mM) in normal Ringer's solution (NRS). RESULTS: Mucosa exposed to HCl in NRS (pH of 1.5 and, to a lesser extent, 4.0) had a significant decrease in Isc, PD, and R, whereas tissues exposed to acetic acid at a pH of < 4.0, propionic and butyric acids at a pH of <or= 4.0, and valeric acid at a pH of <or= 7.0 induced a concentration-dependent effect on reduction in these same values. Values for Isc returned to baseline (recovery of sodium transport) after addition of calcium carbonate in tissues exposed to all concentrations of VFAs except the higher concentrations of valeric acid at a pH of <or= 4.0. Histologic examination revealed cell swelling in the mucosal layers below and adjacent to the stratum corneum in tissues exposed to HCl and VFAs at a pH of <or= 4.0. CONCLUSIONS AND CLINICAL RELEVANCE: The VFAs, especially acetic acid, in the presence of HCl at a pH of <or= 4.0 appear to be important in the pathogenesis of NG mucosal ulcers in horses.

Acetic Acid↗

PubMed2001

Effects of a nonforage diet on milk production, energy, and nitrogen metabolism in dairy goats throughout lactation.

The objective of the experiment was to compare a silage-based control diet (C) with a nonforage diet (NF) in dairy goats throughout lactation in terms of animal performance and energy utilization. Eight Saanen goats were divided into two groups and fed C or NF, a commercial blend that included sunflower meal, cassava, coconut meal, and whole cottonseeds as the main ingredients that was characterized by a small particle size and a high crude protein content. In early, mid, and late lactation (44, 100, and 219 days in milk) the goats were individually tested for dry matter intake (DMI), digestibility, milk yield and composition, milk renneting properties, rumen and plasma parameters, and nitrogen and energy utilization (open circuit respiration chambers). During early and mid lactation, the NF fed goats had a very high DMI: 2946 and 2915 g/d, respectively. Nevertheless, milk yield was similar for the two treatments: 4369 vs. 4342 and 3882 vs. 3841 g/d for goats fed diets C and NF during the first and second periods, respectively. Milk fat content was not statistically different between the two diets. The protein content and rheological parameters of milk were similar for the two diets. Nonprotein nitrogen and urea levels in milk of goats fed NF were significantly higher than goats fed C. Ruminal ammonia and plasma urea nitrogen were also significantly increased by diet NF, due to its high protein content. Plasma glucose, beta-hydroxybutyrate, and nonesterified fatty acids and ruminal volatile fatty acids were not influenced by dietary treatment. Dietary NF significantly decreased energy digestibility (74.5 vs. 65.8%, on average for the lactation, for C and NF, respectively) and had a significantly lower metabolizability (metabolizable energy/intake energy; 66.6 vs 58.0%, on average); however, the efficiency of utilization of metabolizable energy was unaffected by the diet. In conclusion, goats were fed a nonforage diet during the entire lactation without detrimental effect on their health and productive performance.

Animal Feed↗

PubMed1976

Factors influencing rumen microbial growth rates and yields: effects of urea and amino acids over time.

Washed cell suspensions of mixed rumen bacteria were used to evaluate effects of 100% urea-nitrogen and 75% urea-nitrogen plus 25% amino acid-nitrogen in growth media upon microbial growth rate and yield, specific rate of glucose consumption, and incorporation of glucose into mixed cells, carbon dioxide, and end products. Rumen microbial dry matter, nitrogen, ribonucleic acid, deoxyribonucleic acid, glucose disappearance, and production of volatile fatty acids were considerably higher in medium containing urea plus amino acids as compared with urea only. Specific growth rates of microbes were .104 and .203 and mean doubling times were 6.7 and 3.4 h in the urea and urea plus amino acid growth media. Microbial growth in mg per 100 mg glucose used, per mole glucose and per mole adenosine triphosphate (ATP), and specific rate of glucose consumption in mmol per mg cells-h were 19.3, 34.7, 15.4, and .016 with urea, and 24.4, 44.2, 20.6, and .014 with urea plus amino acids. Percentages of catabolized glucose incorporated into microbial cells, carbon dioxide, and end products did not differ between treatments and averaged 19.5, 7.8, and 64.4%.

Adenosine Triphosphate↗

PubMed1985

Dietary influences upon colon carcinogenesis.

A succession of case-control studies of diet and colon cancer, predominantly in developed countries, has produced varied and generally inconsistent findings. The somatic mutation theory of carcinogenesis has dominated much of cancer research for the past 30 years, encouraging emphasis on exogenous genotoxic agents capable of inducing malignant transformation via heritable damage to DNA. Increased risks of human cancers due to various potent chemical carcinogens (found in certain occupations), ionizing radiation, and sunlight have corroborated this "toxicological" view of cancer. Recently, however, greater emphasis has been paid to cancer as a disorder of growth control. The stimulation or derepression of cell growth, via hormones or proto-oncogene activation respectively, is likely to reflect "metabolic" disturbances--such as can be caused by diet. If diet influences large bowel carcinogenesis via mediating metabolic or biochemical factors such as intracolonic pH, production of bile acid metabolites, and fermentative production of volatile fatty acids (which appear to influence mucosal cell stability), then a variety of configurations of diet may have an equivalent net effect upon bowel carcinogenesis. Further, non-specific aspects of diet (such as total energy intake and frequency of eating) may be important; indeed, those two factors were found to be positively and independently associated with large bowel cancer (LBC) risk in our Adelaide case-control study. The accumulating evidence that other factors that alter sex hormonal status and/or hepatobiliary metabolism, and physical aspects of bowel function, are also associated with altered risk of LBC adds further credence to this metabolic model. Such factors are: gender, reproductive history and oral contraceptive usage in women, cholecystectomy, and physical activity.

Bile Acids and Salts↗

PubMed1984

Effects of three benzimidazole anthelmintics on the ruminal fermentation ability of sheep.

The effects of albendazole, fenbendazole and oxfendazole on the fermentation ability of the rumen were assessed in 12 Dorset sheep, using as parameters volatile fatty acid concentration, percentage digestibility of cellulose in vitro and pH. Although the digestibility of cellulose was affected only at high concentrations, volatile fatty acid concentrations were markedly reduced after treatment. Correlation coefficient analysis revealed a significant correlation between digestibility of cellulose and volatile fatty acids, as well as between volatile fatty acids and pH. Despite an evident decrease in volatile fatty acids and digestibility of cellulose, it is suggested that this does not outweigh the advantages derived from the use of these benzimidazoles.

Albendazole↗

PubMed2006

Integration of ruminal metabolism in dairy cattle.

An important objective is to identify nutrients or dietary factors that are most critical for advancing our knowledge of, and improving our ability to predict, milk protein production. The Dairy NRC (2001) model is sensitive to prediction of microbial protein synthesis, which is among the most important component of models integrating requirement and corresponding supply of metabolizable protein or amino acids. There are a variety of important considerations when assessing appropriate use of microbial marker methodology. Statistical formulas and examples are included to document and explain limitations in using a calibration equation from a source publication to predict duodenal flow of purine bases from measured urinary purine derivatives in a future study, and an improved approach was derived. Sources of specific carbohydrate rumen-degraded protein components probably explain microbial interactions and differences among studies. Changes in microbial populations might explain the variation in ruminal outflow of biohydrogenation intermediates that modify milk fat secretion. Finally, microbial protein synthesis can be better integrated with the production of volatile fatty acids, which do not necessarily reflect volatile fatty acid molar proportions in the rumen. The gut and splanchnic tissues metabolize varying amounts of volatile fatty acids, and propionate has important hormonal responses influencing milk protein percentage. Integration of ruminal metabolism with that in the mammary and peripheral tissues can be improved to increase the efficiency of conversion of dietary nutrients into milk components for more efficient milk production with decreased environmental impact.

Animals↗

PubMed1989

Gas chromatographic-mass spectral studies after methylation of metabolites produced by some anaerobic bacteria in spent media.

The gas chromatographic analysis of metabolites such as volatile fatty acids (VFAs) and non-volatile fatty acids (NVFAs) for identification of anaerobic bacteria is now widely performed. Cultures of anaerobes tested for NVFAs as methyl esters were found to contain several unidentified compounds not previously detected and/or reported with methylation procedures. Gas chromatographic-mass spectrometric studies demonstrated that these compounds correspond to the methyl esters of both saturated and unsaturated short-chain fatty acids, and also of 2-hydroxy and 2-oxo acids. The distribution of these acids among different species of anaerobes was determined and their amounts were measured. The effects of supplementing the culture medium with either glucose or amino acids on the production of these acids are described. The use of very polar stationary phases is suggested for a better separation of all NVFAs.

Bacteria, Anaerobic↗

PubMed1997

Effects of vitamin E and selenium on some rumen parameters in lambs.

The effects of supplemented selenium and vitamin E on a number of rumen parameters such as the population of rumen protozoa, pH, concentration of volatile fatty acids and ammonia nitrogen in the rumen content were studied. Eight lambs were randomly allocated into two groups: a control group and an experimental group receiving vitamin E (DL-alpha-tocopheryl acetate, 250 mg/kg of feed) and selenium (sodium selenite, 0.3 mg/kg of feed) supplementation. Samples of rumen content were taken from all lambs three times daily once a week (before feeding as well as 3 and 6 h after feeding) over a period of 10 consecutive weeks. In addition, the lambs were weighed at the end of experiment. The total counts and percentage proportions of rumen protozoa, the pH value, and the levels of ammonia nitrogen and volatile fatty acids were determined in the samples of rumen content. The levels of acetic acid, propionic acid, butyric acid and total volatile fatty acids, the total counts of protozoa, and the percentage proportion of Diplodinium were found to be significantly higher in the supplemented than in the control group (P < 0.05, P < 0.01), whereas the pH values and the percentage proportion of Dasytricha ruminantium were significantly lower in the supplemented group than in the control (P < 0.05). However, there was no statistically significant difference between the two groups in ammonia nitrogen levels. The body mass gain of lambs in the supplemented group was significantly higher than that of the control animals (P < 0.01). Combined selenium and vitamin E supplementation of the lambs' ration caused an increase in the levels of volatile fatty acids, total counts of protozoa, and body mass gain while decreasing the pH value of the rumen content.

Acetic Acid↗

PubMed1976

[Isovaleric acidemia. Study and treatment in 3 brothers].

The cases of 3 sibs presenting with isovaleric acidemia are reported. The first infant died when he was 9 day-old. The two others appear to have benefited from a controlled leucine diet which was introduced from the first days on of life. The clinical symptomatology, highly typical of the disease, is described. Diagnosis was not assessed on amino-acids chromatography but on the chromatography of volatile fatty acids. The mode of treatment is described: peritoneal dialysis, with the object of rounding a crucial cape, and overall controlled leucine diet, but supplemented by essential amino-acids.

Amino Acid Metabolism, Inborn Errors↗

PubMed1991

[The effect of monensin on the fermentation of feed with different proportions of hay and concentrate in an artificial rumen (rumen simulation technic)].

An experiment was conducted with rumen pouch (RUSITEC--Rumen Simulation Technique). In four fermentation vessels (V), percent proportions of hay and barley were as follows: V1--40:60, V2 - 60:40, V3--80:20 and V4--100:0. Every day 5 mg of monensin dissolved in 1 ml 96% ethanol were added to each fermentation vessel. All diets were isonitrogenous, and after an addition of urea the crude protein (CP) content made 13% in each diet. The experiment lasted 12 days: so called steady state period took the first six days when the fermentation conditions were stabilized. Monensin reduced dry matter digestibility, production of total volatile fatty acids, acetic acid, n-butyric and isovaleric acids and acetate: propionate proportion, and it increased the production of propionic and n-valeric acids. The production of methane and CO2 decreased. The higher proportion of hay in diets decreased dry matter digestibility, digestibility of detergent fibre, total and individual volatile fatty acids, CO2, methane energy yield of volatile fatty acids (E), glucose utilization, production of adenosine triphosphate and production of fermented hexoses. The production, utilization and recovery of metabolic hydrogen also decreased. The effectiveness of microbial matter synthesis (YATP = 11.3) was highest during the fermentation of feed containing 60% hay and 40% barley.

Animal Feed↗

PubMed1982

Potentials for pheromones in chimpanzee vaginal fatty acids.

52 vaginal lavages from 33 chimpanzees (Pan troglodytes) of various age classes and reproductive states were examined for volatile fatty acid content by means of liquid gas chromatography. Features of the acid complex in chimpanzee vaginal secretions distinguish these apes from other anthropoids investigated and may constitute and odor signal that identifies chimpanzees. It was not possible to discriminate between the most and least fertile stages of the estrous cycle or among individuals on the basis of acid characteristics. If volatile fatty acids in chimpanzee vaginal secretions are components of a sexual pheromone or pheromones, it is more likely that they are immediate releasers of attraction than of sexual behavior.

Animals↗

PubMed1994

Kinetics of biomethanation of solid tannery waste and the concept of interactive metabolic control.

Anaerobic digestion of calf skin collagenous waste was optimized for a batch process based on accelerated maximal methane yield per gram of input volatile solid. A kinetic analysis with respect to changes in the levels of volatile solid, collagen, amino sugars, amino acids, hydroxyproline, ammonium ions, and volatile fatty acid were followed for a period of 80 d. Distinct metabolic phases included an initial high rate collagenolysis for 4d, with 50% degradation and was followed by an acidogenic phase between 4-12 d with volatile fatty acids levels increasing to 215 mmol/L. Subsequently methanogenesis ensued and was maximal between 12-24 d when volatile fatty acids attained steady state levels. During the period of 80 d, the overall decrease in volatile solid level was 65%, whereas the collagen level declined by 85% with 0.45 L of methane yield/g of volatile solid degraded. Based on the levels of various metabolites detected, the concept of interactive metabolic control earlier proposed has been validated.

Anaerobiosis↗

PubMed2006

Inverse regulation of leptin mRNA expression by short- and long-chain fatty acids in cultured bovine adipocytes.

Leptin is an adipose tissue-derived cytokine plays key roles in the regulation of food intake and energy expenditure. However, regulatory mechanisms of leptin gene expression are not fully elucidated in ruminants that utilize short-chain fatty acids (SCFA), known as volatile fatty acids, as principal energy sources. In this study, we determined effects of SCFA and long-chain fatty acids (LCFA) on leptin expression in bovine adipocytes. Bovine stromal vascular cells isolated from subcutaneous adipose tissue of Holstein cows were cultured to confluence and treated sequentially with dexamethasone and isobutylmethylxanthine for 2 days and insulin and troglitazone for 12 days to achieve full differentiation to adipocytes. The cells started to accumulate lipids 4 days after the onset of treatment, with increased mRNA expression of leptin, as well as aP2, adiponectin, and PPAR-gamma. Removal of fetal calf serum and reduction of glucose in the culture medium of differentiated adipocytes decreased leptin mRNA expression. Subsequent addition of acetate, butyrate, or propionate dose-dependently restored and rather increased leptin expression, while addition of LCFA suppressed it. The stimulatory effect of acetate was abolished by prior treatment of the cells with pertussis toxin and by addition of LCFA. Furthermore, cows fasted for 48h and fed thereafter, elaborate reduced and increased plasma leptin levels, respectively. Thus, these results suggest that plasma leptin levels in cows are inversely controlled at the transcription level by VFA and LCFA, and that the effects of SCFA possibly act through a G protein-coupled receptor for SCFA.

1-Methyl-3-isobutylxanthine↗

PubMedDate not supplied

Effect of diet on Shiga toxin-producing Escherichia coli (STEC) growth and survival in rumen and abomasum fluids.

The gastrointestinal tract of ruminants is the main reservoir for Shiga toxin-producing Escherichia coli (STEC) strains, potentially pathogenic for humans. We used for the first timerumen fluid in which no exogenous carbon source or other supplement was added to compare acid resistance and growth of STEC in physiological physico-chemical conditions. We showed that acidic conditions resulting from the combination of high volatile fatty acid concentration and moderately acidic pH did not alter the survival of STEC, and that human non-O157:H7 STEC isolates were able to persist in the rumen contents in spite of acid stress, low oxygen availability and nutrient deprivation, in the same manner as bovine STEC isolates do. Furthermore, our results support the hypothesis that a grain-rich diet may induce mechanisms of STEC acid resistance in the rumen that allow STEC survival in the abomasum.

Abomasum↗

PubMed2001

Effect of antibiotics, 2-bromoethanesulfonic acid and pyromellitic diimide on methanogenesis in rumen ciliate cultures in vitro.

The effects of penicillin G, streptomycin, chloramphenicol, 2-bromoethanesulfonic acid and pyromellitic diimide on total gas, methane, volatile fatty acid production and food degradability after 24 h of incubation in vitro were investigated in the cultures of two rumen ciliates. The inocula of both rumen ciliates Entodinium caudatum and Epidinium ecaudatum were used at a volume of 34 ml into the 50 ml glass syringes together with the feed and compounds tested. Despite penicillin G--streptomycin treatment methane production in both cultures was significantly decreased by the inhibitors for Epidinium ecaudatum. Methane production of the bacterial fraction of both protozoan species was significantly lower than in the whole cultures. No epifluorescence of methanogens on (or in) the cells of Entodinium caudatum was observed in contrast to Epidinium with which strong epifluorescence of methanogens on the cell surface was detected. Microscopic observation could indicate that the methane production by Entodinium caudatum was probably caused by their intracellular methanogenic activity, while methane production by Epidinium ecaudatum could be related to both the methanogenic bacterial fraction from their external surface and probably also to intracellular activity. Decreased feed degradability and differences in the fermentation end products accompanied the inhibition of methanogenesis in both in vitro cultures. Entodinium caudatum appeared to be more sensitive than Epidinium ecaudatum to the compounds tested.

Alkanesulfonic Acids↗