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At least 163 records · Page 9Linked to original sources
PubMed1975

Effect of volatile fatty acids on water and ion absorption from the goat colon.

The absorption of volatile fatty acids (VFA) and the influence of VFA on the net transport of inorganic electrolytes and water were examined in the temporarily isolated colon of the conscious goat. Perfusion of the colon with a solution similar in content to that normally present in the cecal outflow showed that the net absorption of VFA was more rapid than that of any other ion present in the solution. When the VFA were replaced with Cl, the net absorption of Na and water was reduced nearly twofold. Increasing the pH of the solution from 6.0 to 7.4 in the presence of VFA also resulted in a twofold decreased in the net transport of Na and water. Perfusion of the colon with a hypertonic solution resulted in approximately zero net water transport; however, the net absorption of Na and VFA continued at similar rates as before. These results support the concept that the colon primarily conserves solute followed by the passive movement of water. They also demonstrate that VFA are rapidly absorbed from the goat colon and indicate a striking influence of VFA on the net transport of Na and water. The presence of VFA in the large intestine may be important for normal absorptive function.

Animals↗
PubMed1987

[Effect of the nature of carbohydrates in pig diets on the intestinal absorption of volatile fatty acids].

The appearance of nutrients (amino nitrogen and reducing sugars) and microbial metabolites (volatile fatty acids, VFA) was measured quantitatively in five pigs. After ingestion of a semi-synthetic diet (RFL) containing 22% lucerne meal (6% crude fibre), the absorption of reducing sugars (RS) in the small intestine was high (97.8%) and that of VFA low (880 +/- mmoles/24 hrs.). Ingestion of a semi-synthetic diet (RLa) containing 22% lactose and 6% purified cellulose led to lower absorption of RS (85.2%) and a higher absorption of VFA (1,180 +/- mmoles/24 hrs).

Animals↗
PubMed1987

Influence of supplemental four- and five-carbon volatile fatty acids on forage intake and utilization by steers.

Four ruminally and duodenally cannulated crossbred steers (avg wt 282 kg; trial 1) and 12 intact Hereford steers (avg wt 336 kg; trial 2) were used to evaluate the effects of supplemental four- and five-carbon volatile fatty acids (SFA) on intake and digestion of low-quality prairie grass hay (PH). Steers were fed PH at 1.8% body weight (trial 1) or free choice (trial 2) together with a 34% protein, urea-cottonseed meal supplement (365 g/d trial 1; 500 g/d trial 2) plus 0 or 30 g/d of SFA (Ca-salts of isoC4, C5, and isoC5 acids). Ruminal pH, ammonia-N and total volatile fatty acid concentrations were not influenced (P greater than .10) by SFA. Addition of SFA increased the molar proportions of isobutyric (.84 vs .11; P less than .05), isovaleric (1.01 vs .32; P less than .01), and valeric (.66 vs .47; P less than .07) acids but did not significantly alter the proportions of other acids. Apparent total tract organic matter digestion (51.9 vs 53.7%; P = .095) tended to decrease with SFA, while ruminal and total tract digestion of acid detergent fiber and N were not affected by SFA. Microbial N (MN) flow to the duodenum and efficiency of microbial crude protein (MCP) synthesis were similar for both treatments (66.7 vs 57.4 g MN/d and 29.8 vs 24.4 g MCP/100 g apparently fermented organic matter, respectively). In trial 2, total tract dry matter and acid detergent fiber digestion and voluntary intake were similar for both diets. Results suggest that intake and utilization of prairie hay was not limited by a ruminal deficiency of SFA.

Animal Feed↗
PubMed2004

Use of volatile fatty acids from an acid-phase digester for denitrification.

This study investigates the ability of naturally-produced volatile fatty acids (VFAs) to act as a carbon source for the removal of nitrate-Nitrogen concentrations in the range of 20 to 200 mg/L. The VFAs were generated from an anaerobic digester treating a 1:1 mixture of starch-rich industrial and municipal wastewater. The experiments were carried out at an ambient temperature of 22+/-2 degrees C using 600 mL batch reactors containing VFA-rich effluent from the digester and prepared primary sludge. Nitrates added in the form of a 1 M potassium nitrate solution were observed to completely disappear in conjunction with significant recovery of pH and alkalinity (i.e. biological denitrification). In all cases, denitrification followed zero-order kinetics with an average rate constant of 2.67 mg/[Lh] and a mean specific denitrification rate of 0.0111 g NOx-N/g volatile suspended solids (VSS) per day. The denitrifier population had a preference for acetic acid which occurred in the largest quantity and was exhausted the most rapidly. The next two most abundant VFAs were butyric acid and propionic acid, which were consumed only after acetate concentrations began to decline. The third "choice" of the denitrifiers was valeric acid, thus it appears that denitrifying bacteria have a sequential preference for VFAs. In addition, they prefer VFAs over other more complex soluble organic carbon forms.

Anaerobiosis↗
PubMed1972

Intrajejunal volatile fatty acids in the stagnant loop syndrome.

In the stagnant loop syndrome an abnormal anaerobic flora colonizes the small bowel. Anaerobic organisms are characterized by fermentation reactions leading to the production of volatile fatty acids. This paper describes the measurement of intrajejunal volatile fatty acid concentrations in 11 patients with the stagnant loop syndrome. Nine normal persons and 18 patients with gastrointestinal disease without intestinal stasis acted as controls. Acetate and propionate concentrations were greatly increased in the patients with the stagnant loop syndrome and returned to normal in those patients treated with antibiotics. The measurement of intrajejunal volatile fatty acid concentrations as an index of overgrowth of anaerobic organisms is discussed.

Acetates↗
PubMed1983

Influence of dietary fiber on fecal excretion of volatile fatty acids by human adults.

The ability of dietary fibers to influence the excretion of volatile fatty acids (VFA) in feces was evaluated in five healthy men. Throughout the 63-day study subjects were confined to a metabolic unit and fed semipurified diets. Each diet was consumed for 9 days. Feces were homogenized, and aliquots were analyzed for VFA by a steam distillation procedure followed by gas-liquid chromatography. Individuals showed wide variability in the extent to which they excreted VFA, and there is evidence of some subject-diet interaction. Acetate, propionate and butyrate were generally present in the ratios of 35:25:20, but the proportion of acetate was increased when xylan and corn bran were consumed. The excretion of VFA during the last 3 days of each metabolic period increased with diet as follows: xylan, fiber free, cellulose, pectin and corn bran. Corn bran caused a significant increase in total VFA excretion over the fiber-free diet. Concentration of VFA in excreted feces (or expressed as percentage of fecal solids) increased by diet in the following order: cellulose, xylan, corn bran, pectin and fiber free. Thus, the concentration of VFA in feces showed no relationship to the total quantity of VFA excreted.

Adult↗