Amounts Of Volatile Fatty Acids Research Articles

Volatile Fatty Acids Produced by A Sheep Fed Pure Cellulose as Sole Carbohydrate in its Diet

The quantities of volatile fatty acids (VF A) formed from cellulose in the rumen, and their relation to the amount of cellulose digested, have not previously been determined in vivo. We have recently maintained a sheep on a diet of pure cellulose (500 g), gluten (50 g), and inorganic salts (6-20 g) for a period of several months, and have measured VFA production in the rumen along with the extent of digestion of the cellulose in the animal. A characteristic of the digestion was the formation of large proportions (34--42%) of propionic acid, in contrast to the proportions found in the rumen of sheep at pasture, or fed on dry roughages - where propionic acid, though variable, usually constitutes only about 20% of the total VFA. The findings are summarized in Table 1.

Rates of production of volatile fatty acids in the rumen. V. Evaluation of fodders in terms of volatile fatty acid produced in the rumen of the sheep

l(a). Volatile fatty acid (VFA) production (moles/12 hr) by two sheep fed at 2-hourly intervals on a constant ration containing equal parts of wheaten hay and lucerne hay, showed no significant difference between the sheep or between day-time and night-time values. The precision with which production could be measured over a series of 12-hr periods is given. The quantities of VFA produced in the rumen on successive days varied considerably; the extent of this variation was similar to that occurring in the quantities of faeces passed. (b) Production remained much the same whether the sheep were fed at intervals of 1, 2, or 12 hr. (c) The energy of the VFA produced in the rumen was equivalent to about 54% of the digestible energy of the diet. 2. Similar amounts of VFA were produced from two different mixtures of wheaten hay and lucerne hay, and from lucerne hay alone. 3. A modification in the procedure for measuring VFA production was tested and found to be satisfactory. The necessary apparatus could be readily carried on the back of a freely moving sheep.

Production of Volatile Fatty Acids by Some Lactic Acid Bacteria. II. Selective Formation of Volatile FattyAcids by Degradation of Amino Acids

The kinds and amounts of volatile fatty acids (VFA) produced from single amino acids, modified amino acid mixtures, and pyruvate by resting cells of some streptococci and lactobacilli have been investigated. The effects of pH of substrate, temperature of incubation, and oxygen removal from substrate on VFA production from some selected amino acids were also studied. Two strains of lactic acid bacteria, S. diacetilactis DRC1 and Lactobacillus No. 138, produced acetate from alanine, glycine, or serine, propionate from threonine, isobutyrate from valine, and isovalerate or a valerate from leucine and isoleucine. These reactions may be ascribed mainly to oxidative deamination and decarboxylation. Optimum pH was at neutral or slightly alkaline range, and optimum temperature was 32C for streptococci and 42C for lactobacilli. The removal of oxygen from substrate brought about some changes of total and individual VFA produced from certain amino acids, although there was no reductive deamination. The VFA patterns from amino acid mixtures depended upon a qualitative and quantitative balance of the amino acids. Acetate production from pyruvate by strains DRC1 and No. 138 was also found. Some possible explanations of the mechanism of individual VFA production from amino acids are discussed.

Volatile Fatty Acid Measurements on the Rumen Contents of Lambs Fed Rations of Various Physical Form

A series of four experiments were conducted with lambs to determine the effects of the physical form of the ration and trace mineral supplementation on in vivo rumen molar proportions of volatile fatty acids. Total volatile fatty acid and pH measurements were also made. The ration contained 67% concentrate and 33% roughage. In two of these studies, fistulated lambs were used and in two studies intact lambs were used. The intact lambs appeared to be the better experimental subjects since, for reasons largely unexplained at this time, the effects of the ration treatments were not as pronounced when fistulated lambs were used. Despite these differences, the trends in all studies were similar. The feeding of pelleted rations produced a narrowed acetate to propionate ratio in comparison to similar ground mixed ration. Long hay rations unexpectedly produced narrower acetate to propionate ratios than ground mixed rations. The percent of butyric acid was reduced and that of propionate raised by the addition of cobalt. Percents of iso-butyrate and iso-valerate were lowered and the percent of valerate raised under conditions that narrowed the acetate to propionate ratios. The total quantity of volatile fatty acids tended to be increased by feeding pelleted rations in comparison to ground mixed rations; however, this was not a consistent effect. Acetate to propionate ratios widened with increased length of time after feeding. Acetate production tended to peak approximately four hours after feeding for most rations. However, total acid production had not peaked by six hours on a long hay ration while a peak for ground mixed or pelleted rations was reached previous to two hours after feeding. Rations containing corn cobs produced narrower acetate to propionate ratios than similar rations containing alfalfa hay.

Artificial Rumen Investigations. I. Variability of Dry Matter and Cellulose Digestibility and Production of Volatile Fatty Acids ,

Summary In vitro digestion of feedstuffs was carried out with diluted rumen liquor in glass bottles for 48 hr. Substrates used in the study were forages and a few mixed feeds. Most information was gathered on 39 samples of tall fescue ( Festuca arundinacea ), representing two to four cuttings (pasture height) per year of four genotypes over a 4-yr period. Within-trial variation of dry matter digestibility for all substrates digested was generally small. Cellulose digestibility showed a slightly higher within-trial variability, but this was no greater than those given in the literature for other in vitro procedures. Variability in digestibility between trials, estimated by including a standard alfalfa in every trial, indicated differences in the digesting capacity of rumen liquir collected from the same steer on different days. Oven-dry samples proved more suitable than fresh-frozen samples of tall fescue, based on between-trial variability. Molar percentages of acetic, propionic, butyric, and valeric acids were comparable with those reported in other studies on in vitro digestion of forages. Inoculum used influenced molar percentages of acids produced from the standard alfalfa. Frozen and oven-dried tall fescue samples produced essentially the same molar percentages and total amounts of volatile fatty acids.

Volatile fatty acids in the stools of tropical sprue patients and control subjects.

SummaryThe volatile fatty acids from sprue and non-sprue subjects were analyzed quantitatively and qualitatively, using steam distillation and paper chromatography technics, respectively. The amount of volatile fatty acids per unit weight of feces was practically the same in both groups. The amount passed per day was significantly larger in the sprue than in the non-sprue group.The fatty acids found in both groups were essentially the same in all the samples analyzed: acetic, propionic, n-butyric, n-valeric, caproic, and an unknown insoluble fatty acid. In only a few samples were caprylic and what could be formic acid also observed.

The development of a nonmicrobial off-condition in fresh meat.

It has long been accepted, prima facie, that bacteria are the sole cause of a "sour" condition which is occasionally but persistently found in some fresh beef rounds. Evidence is presented which indicates that this condition often bears no relation to the bacteriology of the muscle involved. It was observed that sour rounds contain elevated quantities of volatile fatty acids. On the basis of experiments in which this condition was artificially induced in vivo, it is suggested that a metabolic block of meat enzymes could account for this build-up of short chain acids.

The Development of a Nonmicrobial Off-Condition in Fresh Meat

It has long been accepted, prima facie, that bacteria are the sole cause of a "sour" condition which is occasionally but persistently found in some fresh beef rounds. Evidence is presented which indicates that this condition often bears no relation to the bacteriology of the muscle involved. It was observed that sour rounds contain elevated quantities of volatile fatty acids. On the basis of experiments in which this condition was artificially induced in vivo, it is suggested that a metabolic block of meat enzymes could account for this build-up of short chain acids.

Fermentation of cellulose and absorption of volatile fatty acids in the cecum of the rabbit

Digestion of cellulose occurs in the czecum of the rabbit, in a manner similar to that of rumen fermentation in ruminants. Cæcal contents exhibit cellulolytic properties. When incubated with extracts of cæcal contents, with the exclusion of oxygen, at 37° C., colloïdal cellulose as well as carboxymethylcellulose are fermented into volatile fatty acids. These acids are easibly absorbed by the cmecal epithelium, as attested by the fact that the amounts of volatile fatty acids in the blood of the mesenteric anterior vein are 8 to 10 times higher than in the blood of the mesenteric and carotid arteries.

Volatile Fatty Acids in Phospholipids

USING the micro-technique of James and Martin1, it has been established that bovine muscle phospholipids contain small amounts of volatile fatty acids, and it is possible that this finding can be extended to animal phospholipids in general. Hitherto, in the absence of techniques for the micro-estimation of the low molecular-weight fatty acids, it has generally been accepted that the fatty acids of phospholipids tend to be of high molecular weight only. A con-secutive series of normal fatty acids from C2 to C10 has been identified in ox perinephric fat2.

The effects of the addition of a poly‐halogenated acetate of ethyl glycol on the fermentation of minced grass and water mixtures

AbstractA study has been made, on the laboratory scale, of the effects on formation of lactic acid and fatty acid, amino‐acid breakdown and pH, obtained by adding a bacteriostatic preparation (SovilonManufactured by the Société des Produits Chimiques ‘Sovilo’, Paris. ) to mixtures of minced grass and water. It has been shown that the effects of this material, in the concentrations used here, have been to diminish the amounts of volatile fatty acids and volatile bases formed during the fermentation of such mixtures. At the same time the formation of lactic acid has been shown to be inhibited to some extent and the partially inhibitory effects on amino‐acid breakdown have also been noted.

The Selective Release of Volatile Acids from Butterfat by Microbial Lipases

Summary Relative substrate specificity patterns, differences in volatile fat acidity of hydrolyzed fat, substrate limitations in the course of the lipolytic reaction, and differences in chromatographic analysis of distillates from hydrolyzed fat indicate that cell-free microbial lipases differ in their ability to release volatile fatty acids from butterfat. Some strain variations were evident. The lipases of seven of nine cultures of G. candidum did not release detectable quantities of volatile fatty acids from butterfat. Two cultures freed butyric acid only. C. lipolytica lipases hydrolyzed butyric acid from the butterfat and five of the six culture lipases also released caproic acid. Butyric, caproic, and caprylic acids were found in distillates of reaction mixtures containing butterfat and the lipases of either P. roqueforti or A. lipolyticum. Butyric acid and an unidentified acid which consistently migrated to an Rf value midway between the caproic and caprylic controls were encountered in P. camemberti lipase-butterfat reaction distillates.

Penicillium roqueforiiによりチーズカードより生成される揮発性脂肪酸について

Changes of volatile fatty acids in whole milk curd, skim milk curd, goat's milk curd and cream inoculated with P. roqueforti and/or Str. lactis were experimented. Quantitative deter-mination of volatile fatty acids was done by modified DUCLAUX's method. Results obtained were as follows: (1) The total amount of volatile fatty acids in incubated whole milk curd was lower than that of commercial Roquefort cheese. (2) By addition of mercerated bread which was previously incubated with P. roqueforti before hooping, volatile fatty acids were produced more than usual inoculation. (3) Volatile fatty acids were produced more in goat's milk curd than in cow's milk curd. (4) By Sir. lactis, production of volatile fatty acids was slight and caproic, caprylic and capric acids were not produced. (5) Lower volatile fatty acids were produced from lactose in skim milk curd and the amount of fatty acids decreased after lactose were by P. roqueforti. (6) Higher volatile fatty acid, as well as lower acids, were produced from cream, but total amount of volatile fatty acids was lower than that of skim milk curd at the beginning of incubation period. (7) Most of the volatile fatty acids were in the form of salt and those in ester form were acetic and butyric.

Volatile fatty acids in portal blood of sheep.

VOLATILE fatty acids—chiefly acetic, propionic and butyric acids—are formed as a result of the fermentation processes in the rumen of sheep and are absorbed through its wall. With the purpose of investigating the concentration of these acids and other constituents in the portal blood during a digestion cycle, that is, the 12-hour period after feeding, a slightly modified London canula was fixed adjacent to the main trunk of the portal vein of two sheep1, which had previously been provided with a rumen canula and an exteriorized loop of the carotid artery. The feed, which consisted of 125 gm. chopped hay, 200 gm. linseed meal and 15 gm. blood meal, was given every 12 hours2, and all was consumed within an hour. The total amount of volatile fatty acids in rumen liquor was determined by steam distillation, and separated into acetic, propionic and butyric plus higher acids using the chromatographic technique of Elsden3. For determination of total volatile acids in blood a modification of the method of McClendon4 was adopted. Blood-sugar estimations were carried out according to Somogyi5 with an accuracy of ±0·11 m.mol. per litre.

THE PRODUCTION OF VOLATILE FATTY ACIDS BY BACTERIA OF THE DYSENTERY GROUP

THESE STUDIES SHOW: 1. A close agreement exists among all the organisms studied in the total quantity of volatile fatty acids produced and in the ratio of formic to acetic, under aerobic conditions, and in the presence of 1 per cent of glucose. 2. When grown upon peptone alone, with free access of air to the cultures, volatile fatty acids are produced in appreciable quantities, although the reaction of the solution has gone more alkaline as shown by colorimetric pH tests. Formic acid is not found, but in its place we obtain propionic acid. 3. Upon exhaustion of air from the non-sugar medium the bacteria again produce formic acid, and in addition some butyric. This is true for both Shiga and non-Shiga cultures. The reaction is distinctly more acid. 4. The presence of glucose in the medium from which the air has been pumped furnishes a condition which provokes about the same type and degree of fermentation that operates in the glucose medium bathed in air at atmospheric pressure. 5. The enormous quantity of formic acid produced by these bacteria may play a significant part in the digestive disturbances and toxic symptoms accompanying their infection of the human intestinal tract.