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PubMed1985

Comparison of pancreatic digestive enzyme secretion induced by volatile fatty acids in mice, Japanese field voles and goats.

The secretory response of the exocrine pancreas to volatile fatty acids was investigated in the isolated preparations of mice, Japanese field voles and goats. The amylase content in pancreases of the voles was half that of the mice, and the trypsin content was four times higher than that of the mice. Amylase release to volatile fatty acids in the goats showed a dose-dependent relationship. The response in the voles was obtained by acetate and propionate, but preparations in the mice were ineffective in response to volatile fatty acids. The results indicate that the pancreatic digestive enzyme secretory function in voles resembles that of ruminants.

Amylases↗
PubMed1975

Gas chromatography of volatile fatty acids. Method involving separation from biological material by vacuum distillation.

A method is described for the quantitation of C2-C5 volatile fatty acids present in biological tissues. It involved recovery of the acids from their biological matrix by vacuum micro-distillation at room temperature, followed by gas phase separation of aqueous solutions on orthophosphoric acid-modified Phasepak Q columns. The subsequent gas chromatographic procedure resolved iso from normal isomers and showed a linear response for each volatile acid over the range 10-400 ng. There was no evidence of ghosting, isomer peak broadening, or peak tailing. Relative molar response values were shown to be linear with carbon number for all the volatile fatty acids studied.

Carbon↗
PubMed2003

Sulfidogenic volatile fatty acid degradation in a baffled reactor.

The effect of staging the sludge bed on volatile fatty acid degradation by sulfidogenic reactors was evaluated in a baffled reactor. In a 5.4 l baffled reactor, containing three equal compartments, a volatile fatty acid (VFA) mixture (acetate:propionate:butyrate ratio 1:2:2 on COD basis; pH 8) was treated under mesophilic (30 degrees C) and sulfidogenic (COD:SO4(2-) ratio: 0.5) conditions for 38 days. At a specific sludge loading rate of 0.50 g COD.gVSS(-1) x d(-1), a COD and sulfate removal of 85% and 30%, respectively, was obtained. In the baffled reactor, staging of the sulfidogenic VFA degradation occurred. Propionate and butyrate were mainly degraded in the first compartment. Their degradation was incomplete, resulting in elevated acetate concentrations in compartment I. In the second and third compartment of the baffled reactor, a net degradation of acetate took place. Acetate was the sole substrate present in compartment III and residual acetate concentrations of about 200 mg/l were present in the effluent at a specific sludge loading of 0.50 g COD x gVSS(-1) x d(-1). Sludges with different maximum specific VFA and acetate degrading activities developed in the first and second compartment. These maximal specific activities were almost equal for sludge present in compartment II and III.

Acetates↗
PubMed1979

[Effect of feeding pelleted feed on the level of volatile fatty acids in the digestive tract of sheep].

In an experiment with wethers we investigated the effect of complete pelleted feed ration on the concentration of volatile fatty acids in the rumen and intestinal tract. The animals consumed daily 1,300 g of dry matter of a diet which contained 41.81% of meadow hay, 25.28% of barley, 15.37% of sawdust, 14.98% of molasses, 1.32% of urea and 1.24% of a vitamin-mineral supplement for a period of six months. The pelleted diet increased the total amount of volatile fatty acids, the content of propionic acid and especially the content of butyric acid. There appeared a decrease in the ratio of acetate: propionate. On the basis of the greater energy efficiency of the volatile fatty acid production the animals fed pelleted feed showed a better energy balance. A higher VFA concentration was determined also in the large intestine and the cecum, which proves the importance of fermentation porcesses in these organs.

Animal Feed↗
PubMed1986

Effects of absorption of large amounts of volatile fatty acids on rat liver metabolism.

The effects of large amounts of volatile fatty acids (VFA) on hepatic metabolism have been investigated in vivo, with rats adapted to a high fiber (HF) diet, or in vitro with isolated hepatocytes. Net absorption of glucose was negligible and lactate production was lower in rats fed the HF diet than in those fed a fiber-free basal diet. VFA (particularly acetate and propionate) were absorbed in very large amounts in rats fed the HF diet. Propionate and butyrate were completely removed by the liver in both groups of rats; the efficiency of acetate uptake was higher in rats fed the HF diet than in those fed the basal diet. Gluconeogenesis was active in rats fed the HF diet, but lactate uptake was very limited in spite of high portal concentrations. Hepatocytes from rats fed the HF diet utilized VFA at different rates: acetate was poorly utilized, propionate utilization plateaued at about 1 mM external propionate, whereas butyrate utilization was utilized about twice as efficiently. Propionate and butyrate displayed opposite effects on lactate utilization. The stimulating effect of butyrate prevailed over the inhibitory effects of propionate, at high concentrations (2 mM). However, the results at lower concentrations (less than or equal to 0.5 mM) suggest that, owing to its higher portal concentrations, the effects of propionate on lactate uptake might prevail in vivo. The effects of acetate in vivo might be greater than on isolated hepatocytes.

Acetates↗
PubMed1976

Insect growth regulators and in vitro volatile fatty acid production.

Three insect growth regulators were tested for their effects on in vitro volatile fatty acid production. Each material was tested at 100 and 200 ppm of feed in a triplicated trial. At the concentrations used, there was a trend toward lowered acetate:propionate ratios with inconsistent effects on total volatile fatty acid production for all materials. Of the individual acids, only the relative production of valeric was affected significantly.

Alkenes↗
PubMed1994

Effect of intraruminal propionic acid infusion on metabolism of mesenteric- and portal-drained viscera in growing steers fed a forage diet: I. Volatile fatty acids, glucose, and lactate.

This experiment investigated the effect of intraruminal infusion of propionic acid on ruminal VFA metabolism and the absorption of nutrients by the mesenteric- and portal-drained viscera of seven Friesian steers, average BW 127 kg, fed a dried grass-pellet diet. Each received by random allocation 0 (control), .5, or 1.0 mol of propionic acid/d for 7 d. Ruminal acetate and propionate irreversible loss rates and carbon exchange between VFA and CO2 were measured during continuous intraruminal infusions of 2-14C-acetic acid and 2-14C-propionic acid. Ruminal acetate irreversible loss rate was not affected by propionic acid infusion (overall mean 8.09, error mean square [EMS] 2.68 mol/d), whereas propionate irreversible loss increased incrementally with PA supply (3.22 vs 4.16, EMS .61 mol/d, for control and 1.0 mol of propionic acid/d, respectively, P = .09). Glucose irreversible loss rate was increased at the highest level of PA infusion (2.84, 2.83, and 3.22, EMS .06 mol/d, for control, .5, and 1.0 mol of propionic acid/d, respectively; P = .02 for control vs .5 + 1.0), although the proportion of glucose irreversible loss derived from propionate remained constant (.6). Net absorption into venous blood showed that propionate was extensively metabolized in the rumen wall and that the tissues of the small intestine utilized acetate. Utilization of glucose was reduced in portal tissues as a result of intraruminal infusion, and the data were used to derive a model of glucose and lactate interrelationships in gut tissues.

Absorption↗
PubMed1979

Efficiency of utilization of volatile fatty acids for maintenance and energy retention by sheep.

1. Two experiments were conducted with lambs sustained entirely by intragastric infusion of volatile fatty acids (VFA), protein, minerals and vitamins. 2. In the first experiment to determine the effects of VFA on nitrogen retention four mixtures of VFA (B, C, D and E) were used containing acetic, propionic and butyric acid in the following molar proportions respectively: 45, 45 and 10; 55, 35 and 10; 65, 25 and 10; 75, 15 and 10. The level of infusion was 836 kJ/live weight0.75 per d and the design was a 4 X 4 Latin square with 14 d periods. There were no significant differences in the N balance between the different mixtures of VFA though mixture B tended to give the highest N retention. 3. Thirty-two lambs were used in the second experiment for measurements of heat production in closed-circuit respiration chambers. Six mixtures of VFA were used. These included mixtures B-E from Expt 1 and in addition two mixtures (A and F) containing acetic, propionic and butyric acid in the following molar proportions respectively: 35, 55 and 10; 85, 5 and 10. The heat production was measured both at 450 and 900 kJ/W0.75 per d, except for mixture F, where it was not possible to achieve a rate of infusion in excess of 675 kJ/W0.75 per d. 4. The energy required for maintenance was determined to be 0.45 +/- 0.02 MJ/kg live weight0.75 per d regardless of the mixture used. 5. The efficiency of utilization for fattening (kf) values for the six mixtures were 0.78, 0.64, 0.57, 0.61, 0.61 and 0.59 for mixtures A, B, C, D, E and F respectively. Only mixture A was significantly better utilized than the other mixtures. This mixture also gave the most efficient N utilization. 6. It is concluded from this evidence that differences in kf for diets normally given to ruminants cannot be attributed to differences in utilization of volatile fatty acids.

Animals↗
PubMed1975

Digestibility and volatile fatty acids in steers and wethers at 21 and 32 C ambient temperature.

Four steers and four closely shorn wethers, each with ruminal fistula, were used in a reversal experiment to compare the direct effect of 21 and 32 C ambient temperatures (70% relative humidity) on dry matter digestibility and ruminal volatile fatty acid concentrations. Pelleted alfalfa intake was held constant at 2.3% of body weight. Orts were placed into the rumen via fistula. Dry matter digestibility was determined by total collection during the last 7 days of each trial. On one of the last 2 days, ruminal fluid was sampled 11 times within 13 h. At 32 C, the steers suffered considerable heat stress as evidenced by a mean 1.6 C increase in body temperature, reduced heart rate, and greatly increased respiration rate. The wethers, however, exhibited only increased respiration rate at 32 C. Extent of digestion increased five percentage units for the steers but did not change for the wethers at the high temperature. Temperature caused only slight shifts in ruminal volatile fatty acid concentrations. Volatile fatty acid concentrations were much higher in steers than in wethers. The frequently observed effects of heat stress on intake and digestibility are mediated by changes in rate of passage as a result of altered thyroid secretion rates.

Animals↗
PubMed1973

Activation of volatile fatty acids in bovine liver and rumen epithelium. Evidence for control by autoregulation.

1. The total capacities of homogenates of bovine liver and rumen epithelium to activate acetate, propionate and butyrate were determined. 2. Activating capacities were assayed by measuring the rate of formation of the corresponding CoA esters. The methods used for determining the concentrations of the CoA esters allowed the CoA esters of acetate, propionate and butyrate to be distinguished. It was thus possible to investigate the effect of the presence of a second volatile fatty acid on the rate at which a given volatile fatty acid was activated. 3. The propionate-activating capacity in rumen epithelium was decreased by about 87% in the presence of butyrate, the acetate-activating capacity in liver was decreased by about 55% in the presence of either propionate or butyrate, and the butyrate-activating capacity in liver was decreased by about 40-50% in the presence of propionate. 4. All three activating capacities in liver appeared to be located in the mitochondrial matrix and membrane. The three activating capacities had similar locations to each other in rumen epithelium as well, although in this case activity was more evenly divided between the mitochondria and the cytoplasm. 5. The relative activating capacities towards the volatile fatty acids in the two tissues, together with the ability of one volatile fatty acid to inhibit the activation of another volatile fatty acid, appear to ensure that butyrate is mainly metabolized in the rumen epithelium and that propionate is metabolized in the liver.

Acetates↗
PubMedDate not supplied

[The possibility of using the data on the content of volatile fatty acids for the indirect demonstration of the causative agents of suppurative-inflammatory diseases in the pathological material].

The use of the quantitative content of volatile fatty acids as marker for the indication of the causative agents of pyo-inflammatory diseases in material taken from wounds is proposed. Thus, in 71% of cases the detection of acetic acid in a purulent wound coincided with the bacteriological isolation of monocultures, as well as associations, of facultative anaerobic bacteria. The analysis of isobutyric, butyric, isovaleric, valeric and acetic acids permitted the rapid detection of associations of obligate and facultative anaerobic bacteria in an individual patient. Changes in the quantitative content of volatile fatty acids in pathological material integrally reflected the dynamics of the causative agents of purulent infections and the effectiveness of the prescribed therapy.

Acute Disease↗