The rates of production of volatile fatty acids in the rumen. IV. Individual and total volatile fatty acids

1967 ◽  
Vol 18 (1) ◽  
pp. 107 ◽  
Author(s):  
RA Weller ◽  
FV Gray ◽  
AF Pilgrim ◽  
GB Jones

(1) In sheep fed at 12-hr intervals on roughage diets (lucerne and wheaten hay) total volatile fatty acid production in the rumen has been measured by an isotope dilution procedure based on the infusion of a single 14C-labelled volatile fatty acid. (2) Total and individual acid production has been measured through the infusion of a mixture of 14C-labelled acids in which the proportions of individual acids were such that transfers of 14C by interconversions between the acids were balanced. (3) The findings support the view that the mixture of acids produced in the rumen is similar in composition to that present in the rumen fluid throughout the feeding cycle. Consequently it was possible to determine the production of individual acids by a relatively simple procedure requiring only the infusion of a single 14C-labelled acid and measurement of the concentration of 14C in a composite sample of the acids in the rumen fluid collected throughout the feeding cycle. This procedure is considered suitable for routine use; automatic sampling of rumen fluid still further reduces the work involved. (4) The infusion of certain mixtures of 14C-labelled fatty acids showed that the composition of the acid initially formed in the rumen was acetic 77–83%, propionic 15–18%, and butyric 1–7% according to the diet given and the time elapsed after feeding. From 50 to 80% of the butyric acid in the final volatile acid product was formed from acetic acid. Degradation of 14C-labelled butyrate formed from [1-14C] acetate in the rumen showed 93% of the 14C to be nearly evenly divided between carbon atoms C1 and C3.

1957 ◽  
Vol 49 (2) ◽  
pp. 180-183 ◽  
Author(s):  
A. John ◽  
G. Barnett ◽  
R. L. Reid

1. The findings presented in two previous papers on the yields of volatile fatty acids, obtained by the action of rumen liquor in the artificial rumen, from fresh grass, dried grass and the water-soluble and water-insoluble separates of the latter, have been amplified by a consideration of the acids similarly obtained from specimens of chemically prepared crude fibre and cellulose, from four of the dried grass specimens.2. The proportions of different volatile fatty acids from grass crude fibre and grass cellulose resemble those obtained from cellulose powder, propionic acid being produced in greatest relative yield.3. A general review of these latter findings, in relation to those already presented, has been given.


RSC Advances ◽  
2015 ◽  
Vol 5 (62) ◽  
pp. 50033-50039 ◽  
Author(s):  
Xue Yang ◽  
Lei Wen ◽  
Xiang Liu ◽  
Si Chen ◽  
Yayi Wang ◽  
...  

Although many pretreatment methods are employed to enhance the hydrolysis of waste activated sludge (WAS), the bioconversion of soluble complex substrates needs improvement to produce higher volatile fatty acids (VFAs).


2021 ◽  
Author(s):  
Gamsathvani Sivanantham

In the following report, the effects of substrate type and pretreatment type on the production of volatile fatty acids during anaerobic digestion was analyzed. First, the effects on volatile fatty acid production due to substrate type were investigated. It was determined that wastes that consisted of higher concentrations of carbohydrates would generate higher concentrations of volatile fatty acids during anerobic digestion. In the investigation it was evident that food waste had higher volatile fatty acid yields compared to sludge due to the carbohydrate content. Furthermore, the effects on volatile fatty acid production due to pretreatment type were also investigated. Thermal, chemical, physical and combined pretreatments were analysed. The various types of the different pretreatments and their effects on volatile fatty acid production during anaerobic digestion were discussed in depth.


1968 ◽  
Vol 21 (1) ◽  
pp. 89 ◽  
Author(s):  
VJ Williams ◽  
TR Hutchings ◽  
KA Archer

Ten acute experiments were performed on sheep to study the relative rates of absorption of volatile fatty acids in acid solution from the reticulo-rumen and abomasum. When the solutions in the two organs were approximately the same in initial tonicity, pH, and volatile fatty acid concentration, the total volatile fatty acid was absorbed at about equal rates from both the reticulo-rumen and the abomasum. The individual volatile fatty acids were absorbed from the abomasum at different rates; the rate was faster the greater the number of carbon atoms in the molecule. Ammonia in acid solution was not absorbed from the reticulo-rumen or from the abomasum.


2021 ◽  
Author(s):  
Gamsathvani Sivanantham

In the following report, the effects of substrate type and pretreatment type on the production of volatile fatty acids during anaerobic digestion was analyzed. First, the effects on volatile fatty acid production due to substrate type were investigated. It was determined that wastes that consisted of higher concentrations of carbohydrates would generate higher concentrations of volatile fatty acids during anerobic digestion. In the investigation it was evident that food waste had higher volatile fatty acid yields compared to sludge due to the carbohydrate content. Furthermore, the effects on volatile fatty acid production due to pretreatment type were also investigated. Thermal, chemical, physical and combined pretreatments were analysed. The various types of the different pretreatments and their effects on volatile fatty acid production during anaerobic digestion were discussed in depth.


1996 ◽  
Vol 127 (2) ◽  
pp. 231-246 ◽  
Author(s):  
J. Dijkstra ◽  
J. France ◽  
H. D. St. C. Neal ◽  
A. G. Assis ◽  
L. J. M. Aroeira ◽  
...  

SUMMARYA dynamic model of digestion and absorption of nutrients in cattle fed sugarcane-based diets is described. There are 11 rumen state variables, and four zero pools representing absorbed nutrients. The rumen state variables represent nitrogen, carbohydrate, long chain fatty acid, microbial and volatile fatty acid pools. The zero pools relate to absorbed amino acids, glucose, long chain fatty acids, and volatile fatty acids. The flux equations are described by mass-action and Michaelis-Menten forms. Wherever possible, data derived from trials with cattle fed sugarcane-based diets were used to parameterize the model. Sensitivity analyses revealed that stability and behaviour of the model was generally satisfactory. The model was most sensitive to changes in fractional passage and substratehydrolysis rates and to the microbial maintenance requirement. Within the limited information available for comparison, the simulations agreed with observations of fibre flows and ammonia and volatile fatty acid concentrations in rumen fluid. Duodenal non-ammonia nitrogen flow was consistently underpredicted and reasons for this underprediction are suggested.


1984 ◽  
Vol 64 (5) ◽  
pp. 29-30 ◽  
Author(s):  
R. W. HODGE ◽  
M. J. WATSON ◽  
C. KAT

The concentration of ammonia nitrogen and branched chain fatty acids was significantly higher (P < 0.05) in ruminal fluid of sheep given lupins than in those given wheat but there were no significant differences in pH, total volatile fatty acid concentration or molar proportions of acetate, propionate or butyrate. Key words: Sheep, wheat, lupins, rumen, fermentation


1967 ◽  
Vol 18 (4) ◽  
pp. 625 ◽  
Author(s):  
FV Gray ◽  
RA Weller ◽  
AF Pilgrim ◽  
GB Jones

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.


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