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PubMed1983

Net absorption and ruminal concentrations of metabolites in nonpregnant dry Holstein cows before and after intraruminal acetic acid infusion.

Objectives were to define daily patterns of net absorption of various nutrients and to assess effects of intraruminal infusion of acetic acid on concentrations of ruminal fluid and net absorption of various metabolites. These characteristics were measured in three nonpregnant, dry Holstein cows (491 kg) at hourly intervals for 24 h before and after 5 days of intraruminal infusion of acetic acid to provide energy equal to 10% of daily intake of metabolizable energy. Cows were fed a completely mixed, 60% corn silage, 40% grain supplement diet at maintenance intake; daily rations were split into two feedings. Net rates of absorption were greatest after feeding and least during early morning. Net absorption of all metabolites measured was similar for the two daily feeding intervals, indicating daily net absorption could be calculated from either feeding interval. Intraruminal infusion of acetic acid caused increased ruminal and plasma concentrations of acetate, increased net absorption of acetate, and almost a twofold increased loss of urea-nitrogen from plasma to the gut. Sixty-nine percent of acetic acid infused was accounted for by increased net absorption of acetate. Ruminal fluid concentrations and net absorption of other volatile fatty acids were not affected by infusion of acetic acid. Net absorptions of ammonia-nitrogen, L-lactate, and glucose likewise were not affected. Net absorption of volatile fatty acid and L-lactate was 43% of daily intake of metabolizable energy.

Absorption↗

PubMed1986

Effect of clindamycin on the ability of a continuous culture of colonic bacteria to ferment carbohydrate.

A continuous culture model of the proximal colon was used to study the effect of clindamycin on the ability of colonic bacteria to ferment carbohydrate. Six steady state anaerobic cultures of human faeces, in a medium simulating ileostomy effluent, were treated with 26 micrograms/ml clindamycin. They were paired with six untreated cultures, run under identical conditions. Clindamycin treatment eliminated the anaerobic bacteria, significantly decreased osmolality and the output of volatile fatty acids, particularly propionic acid and increased the residual carbohydrate concentration. Doubling the amount of carbohydrate in the medium increased osmolality and the production of volatile fatty acid, though the response of clindamycin treated cultures was less than that of untreated cultures. Attempts to introduce Clostridium difficile into three pairs of cultures were successful in only two cultures after administration with clindamycin and when a heavy inoculum (10(6)-10(9) organisms) had been used.

Bacteria↗

PubMedDate not supplied

Volatile fatty acid-sensing system involving coenzyme-A transferase.

On-site monitoring of volatile fatty acids (VFAs), such as propionate, is industrially and medically important. The present study developed a VFA biosensing system comprised of two recombinant enzymes, propionate coenzyme A (CoA) transferase (PCT) from Clostridium propionicum and acyl-CoA oxidase from Arabidopsis thaliana. This system produced hydrogen peroxide in the presence of acetyl-CoA, oxygen, and VFA substrates, which could be quantified by colorimetric methods using peroxidase and dye reagents (e.g., p-aminobenzoic acid plus 4-aminoantipyrine or Amplex Red). The use of PCT and acetyl-CoA, rather than acyl-CoA synthetases (ACS) and CoA-SH, obviated a background reaction of dye reagents with CoA-SH and enabled very sensitive detection of VFAs (down to 1 microM propionate, more than 100-fold more sensitive compared to previously developed ACS biosensors). We demonstrated its utility by measuring propionate concentrations in serum and fermentation samples. Results suggest that our biosensing system is applicable to the detection of propionate in medical and fermentation samples.

Animals↗

PubMedDate not supplied

Sulphite analysis of food ingredients: false positive responses with butter flavourings in the optimized Monier-Williams method.

The analysis of commercial butter flavouring materials for sulphite by the optimized Monier-Williams method revealed detectable levels of apparent sulphur dioxide (1810 ppm for butter oil, 5760 ppm for butter flavour, and 14.5 ppm for butter derivative) even though the manufacturers claimed that no sulphites were used in processing these ingredients. The presence of volatile fatty acids in these ingredients may explain the anomalous results. Volatile fatty acids were found to interfere with the optimized Monier-Williams method for sulphite determination, detectable levels of titratable acid being found in the hydrogen peroxide trap with amounts of volatile fatty acids as low as 0.3 g. The levels of volatile fatty acids in foods would not be predicted to cause significant interference in the analysis of sulphite residues by the optimized Monier-Williams method. However, this analytical procedure is not recommended for the analysis of sulphite residues in food ingredients containing substantial amounts of volatile fatty acids. Alternative methods for the detection of residual sulphite, such as the sulphite oxidase assay and the colorimetric para-rosaniline method, are not subject to interference by volatile fatty acids.

Butter↗

PubMed1983

Effect of lasalocid sodium on rumen fermentation and digestion in sheep.

Four adult sheep were fed 4 diets successively according to a Latin-square design. They were fitted with a rumen cannula and with simple cannulae at the duodenum and ileum. The basal diet (L0) was composed of highly-pressed ensiled sugar beet pulp (56.2%), cereal (barley and corn: 27.6%), urea (1.5%) and wheat straw (14.1%). Lasalocid sodium was added to obtain the following respective amounts: 21 ppm for diet L1, 43 ppm for diet L2 and 64 ppm for diet L3 (table 1). In the rumen, lasalocid significantly increased the molar proportion of propionic acid in the volatile fatty acids (VFA) mixture at the expense of the acetic and butyric acid proportions. The total VFA concentration decreased, especially with 43 and 64 ppm (table 2). Accordingly, the proportion of methane in rumen gases decreased. The ciliate population was always lower in animals fed experimental diets L1, L2, and particularly L3. The non-food-particle-associated bacterial population also decreased; the differences were significant only with the highest doses of lasalocid (L3). At the same time, bacterial cellulolytic activity increased 10%, indicating that qualitative modifications had taken place in the rumen bacterial population (table 3). Overall digestive utilization of organic matter (OM) decreased when lasalocid was added to the diets. This was due to a considerable reduction in forestomach digestion (12% decrease) (table 4). A greater supply of OM rich in cell-wall carbohydrates in the duodenum would explain the lower digestibility in the small intestine of animals given diet L1 and especially the L2 and L3 diets. No significant shift in digestion was noted in the large intestine. The composition of the non-ammonia nitrogen that entered the duodenum of sheep given lasalocid differed from that noted with the control diet (L0) (table 5). The amount of microbial proteins was significantly lower, whilst the proportion of non-degraded feed proteins was higher. The efficiency of microbial synthesis (bacterial proteins/kg OM truly digested in the rumen) was not significantly modified by lasalocid. All these modifications in digestion observed with these diets, and resulting from changes in the qualitative and quantitative composition of flora and fauna in the rumen, have an effect on nitrogen and energy utilization in the ruminant.

Animals↗

PubMed1997

Protein utilization during energy undernutrition in sheep sustained by intragastric infusion. Effect of body fatness on the protein metabolism of energy-restricted sheep.

The effect of body fat content on the protein metabolism of energy-restricted sheep has been studied in two experiments. In the first experiment, six Suffolk-cross wether sheep, three weighing about 39 kg and three of about 61 kg, were given progressively increasing amounts of casein-N from 0 to 3000 mg N/kg metabolic body weight (W0.75) daily with constant energy, 91 kJ/kg W0.75 daily, from a high-propionic acid mixture of volatile fatty acids (VFA). In the second experiment, two lean and two fat sheep of similar body weights were given progressively increasing amounts of casein with the same VFA mixture. All the animals attained a positive N balance when they were in negative energy balance. N balance was not affected by body fatness of the magnitude studied, although lean animals utilized increasing levels of standard VFA (acetate-propionate-butyrate 65:25:10, molar proportions) infusion for N accretion more efficiently than fat animals. Endogenous energy was utilized for protein accretion with an efficiency of 0.56. Supply of glucogenic VFA equivalent to 28 mmol glucose/kg W0.75 reduced fasting N excretion by 39%. Fasting heat production decreased from 335 to 300 kJ/kg W0.75 with the infusion of casein and glucogenic VFA. It is argued that fasting induces additional heat losses due to raised protein metabolism and is unsuited as a baseline for dietary assessment.

Animals↗

PubMed2003

Digestion and nutrient net fluxes across the rumen, and the mesenteric- and portal-drained viscera in sheep fed with fresh forage twice daily: net balance and dynamic aspects.

Digestion and portal net flux of nutrients were studied in sheep fed twice daily with fresh orchard-grass. Digestive flows were measured in six fistulated sheep using the double-marker technique. Three sheep were fitted with catheters and blood-flow probes, allowing nutrient net flux measurements across the portal-drained viscera (PDV), the mesenteric-drained viscera (MDV) and the rumen. Total tract apparent digestion of N was similar to portal net appearance of N, calculated as the sum of free amino acids (FAA), peptide amino acids (PAA), NH3, and urea net fluxes. PAA accounted for 25 % of non-protein amino acid net release across the PDV. With the exception of glycine and glutamate, the small intestine was the main contributor to this PAA net release. The essential amino acid (EAA) apparent disappearance between the duodenum and the ileum was lower than the net appearance of EAA (FAA + PAA) across the MDV. The value of PDV:MDV flux of free EAA was, on average, 78 %. The rumen accounted for 30 % of the net uptake of EAA by the PDV tissues not drained by the mesenteric vein. Rumen net release of acetate, propionate, butyrate, 3-hydroxybutyrate, and lactate accounted for 70, 55, 46, 77 and 52 %, respectively, of their portal net releases. Conversely, the small intestine was a net consumer of arterial acetate and 3-hydroxybutyrate. Dynamic study of nutrient net fluxes across the PDV showed that throughout a feeding cycle, the liver faced a constant flux of amino acids (AA), whereas volatile fatty acid and NH3 net fluxes varied in response to the meal. The present study specified, in forage-fed sheep, the partitioning of nutrient net fluxes across the PDV and the role of peptides in portal net release of AA.

Amino Acids↗

PubMed2006

Effects of dietary neutral detergent fibre on production performance, nutrient utilization, caecum fermentation and fibrolytic activity in 2- to 3-month-old New Zealand rabbits.

An experiment was conducted to determine the effects of different dietary neutral detergent fibre (NDF) levels on growth performance, nutrient utilization, caecum development, caecal fermentation, slaughter performance, immune organ and fibrolytic activity in 2- to 3-month-old New Zealand meat rabbits. Eighty 2-month-old rabbits were allocated in individual cages for five treatments in which they were fed each diet with NDF at 240, 270, 300, 330 and 360 g/kg respectively. The results are as follows: the average daily gain of 300 g/kg NDF group was the highest (30.09 g/day) and higher than that of 240 g/kg NDF group (p < 0.05). The feed/gain ratio of 300 g/kg NDF group was the lowest (4.27) and lower than those of 240 and 360 g/kg NDF groups (p < 0.05). The coefficient of total tract apparent digestibility (CTTAD) of energy, crude protein, crude fibre and ether extract decreased when dietary NDF increased (p < 0.05); CTTAD of NDF increased when dietary NDF increased (p < 0.01). Digestible nitrogen and retained nitrogen of 240, 270, 300 and 330 g/kg NDF groups were higher than that of 360 g/kg NDF group (p < 0.05). The caecum weight, the proportion of caecum weight to body weight and the acetic acid ratio of volatile fatty acid rose when dietary NDF concentration increased (p < 0.05). The NH(3)-N concentration of caecum dropped when dietary NDF increased (p < 0.05). The fibrolytic activity increased when the dietary NDF increased (p < 0.01).

Animals↗

PubMed2003

Effects of hydrochloric, acetic, butyric, and propionic acids on pathogenesis of ulcers in the nonglandular portion of the stomach of horses.

OBJECTIVE: To identify the pathogenesis of gastric ulcers by comparing injury to the nonglandular gastric mucosa of horses caused by hydrochloric acid (HCl) or volatile fatty acids (VFAs). SAMPLE POPULATION: Gastric tissues from 30 horses. PROCEDURE: Nonglandular gastric mucosa was studied by use of Ussing chambers. Short-circuit current (Isc) and potential difference were measured and electrical resistance calculated for tissues after addition of HCl and VFAs to normal Ringer's solution (NRS). Tissues were examined histologically. RESULTS: Mucosa exposed to HCl in NRS (pH, 1.5) had a significant decrease in Isc, compared with Isc for mucosa exposed to NRS at pH 4.0 or 7.0. Also, exposure to 60mM acetic, propionic, and butyric acids (pH, 4.0 or 1.5) caused an immediate significant decrease in Isc. Recovery of sodium transport was detected only in samples exposed to acetic acid at pH 4.0. Recovery of sodium transport was not seen in other mucosal samples exposed to VFAs at pH < or = 4.0. CONCLUSIONS AND CLINICAL RELEVANCE: Acetic, butyric, and propionic acids and, to a lesser extent, HCl caused decreases in mucosal barrier function of the nonglandular portion of the equine stomach. Because of their lipid solubility at pH < or = 4.0, undissociated VFAs penetrate cells in the nonglandular gastric mucosa, which causes acidification of cellular contents, inhibition of sodium transport, and cellular swelling. Results indicate that HCl alone or in combination with VFAs at gastric pH < or = 4.0 may be important in the pathogenesis of gastric ulcers in the nonglandular portion of the stomach of horses.

Acetic Acid↗

PubMed2004

Application of Methanobrevibacter acididurans in anaerobic digestion.

To operate anaerobic digesters successfully under acidic conditions, hydrogen utilizing methanogens which can grow efficiently at low pH and tolerate high volatile fatty acids (VFA) are desirable. An acid tolerant hydrogenotrophic methanogen viz. Methanobrevibacter acididurans isolated from slurry of an anaerobic digester running on alcohol distillery wastewater has been described earlier by this lab. This organism could grow optimally at pH 6.0. In the experiments reported herein, M. acididurans showed better methanogenesis under acidic conditions with high VFA, particularly acetate, than Methanobacterium bryantii, a common hydrogenotrophic inhabitant of anaerobic digesters. Addition of M. acididurans culture to digesting slurry of acidogenic as well as methanogenic digesters running on distillery wastewater showed increase in methane production and decrease in accumulation of volatile fatty acids. The results proved the feasibility of application of M. acididurans in anaerobic digesters.

Acetates↗

PubMed2004

Effect of a monensin controlled-release capsule on rumen and blood metabolites in Florida Holstein transition cows.

The objective of this study was to determine the effect of a monensin controlled-release capsule administered intraruminally at dry-off on rumen volatile fatty acids, NH3, lactate, pH, and energy blood metabolites in transition dairy cows fed Florida typical diets. In March 2003, 24 cows (10 primiparous and 14 multiparous) dried-off 50 to 70 d before expected parturition were randomly assigned to a treatment (n=12, oral capsule of monensin) or a control group (n=12, no capsule). Both groups received the same diet and were exposed to the same environment and management conditions. At assignment, at 21 d before expected parturition, at calving, and at 7, 14, and 21 d postpartum, blood samples were taken and body condition scores were determined. At 10 d postpartum, rumen and blood samples were obtained in the morning before the first feeding and at 2, 4, and 6 h after feeding. Serum nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), and glucose were measured. Rumen samples were analyzed for concentrations of acetic, propionic, butyric, L- and D-lactic acids, and NH3. Data for rumen and blood metabolites were analyzed by ANOVA, mixed models for repeated measures. Volatile fatty acids were not different between groups. Multiparous treated cows had a significant reduction in rumen NH3 at 6 h after feeding. Treatment with monensin significantly increased body condition score at calving in multiparous cows. During the postpartum period, NEFA and BHBA were noticeably lower in treated than in control primiparous cows. This difference was not observed in multiparous cows.

3-Hydroxybutyric Acid↗

PubMedDate not supplied

Blood acid-base equilibrium in experimental acidosis of the rumen in sheep.

Blood acid-base equilibrium in experimental acidosis of the rumen in sheep. Acta Physiol. Pol., 1979, 30 (4): 543--551. Experimental acidosis of the rumen was induced in sheep infusing into it through a fistula a solution of saccharose and solutions of different volatile fatty acids and lactic acid. Arterial-blood acid-base equilibrium indices were determined by the Astrup micromethod with an Acid-Base-Cart ABC-1 unit. It was found that during saccharose-acidosis partly compensated metabolic acidosis develops and that acid-base equilibrium disturbances are caused by all volatile fatty acids and lactic acid. When they are infused in equimolar amounts into the rumen the strongest and earliest disturbances in that equilibrium are caused by acetic acid, followed by butyric, lactic and propionic acids.

Acidosis↗

PubMedDate not supplied

[The effect of increasing additions of low-esterified pectins in the diet on the metabolism of laying hens--tested by pair-feeding studies].

A series of trials was carried out with 32 laying hens in order to study metabolism after addition of low methylated citrus pectin in levels of 2% and 6%. The following results should be pointed out: Addition of pectic substances reduced feed-intake and stimulated water intake. The limited tolerance for pectins resulted in an increasing water-content of the excreta with a rise of the concentration of volatile fatty acids and an alteration of their spectrum. In consequence of supplementation with pectins a considerable loss of body weight could be established, which exceeded the expected effects of reduced energy-intake. The egg production was impaired by addition of pectin. In the serum the level of total lipids, cholesterol, triglycerides, phospholipids, furthermore of bile acids diminished. These effects exceeded remarkably those induced solely by reduced feed-intake. The level of volatile fatty acids in the serum was elevated as result of the supplementation with pectic substances.

Animals↗

PubMed1995

Fermentation of radiolabelled substrates by batch cultures of caecal microflora maintained in a continuous-flow culture.

Glucose- and lactose-based media containing either 14C-labelled glucose, galactose, lactose or lactic acid were inoculated with anaerobic cultures of chicken caecal bacteria maintained for 121 d in a continuous-flow (CF) culture. The culture was previously shown to reduce Salmonella colonization in the caeca of chicks inoculated with the culture and the reduction was associated with increases in volatile fatty acids. The distributions of 14C were determined among the fermentation products, especially acetic, propionic and lactic acids. After 12 h of incubation and fermentation, variations were observed in the total amounts of 14C, from each 14C-labelled substrate, detected as acetic and propionic acids in the glucose- and lactose-based media, respectively: 92.9 and 89.4% of 14C-glucose, 77.0 and 44.0% of 14C-galactose, 0.0 and 76.9% of 14C-lactose, and 76.5 and 93.2% of lactic acid in the two media, respectively. The results from this study indicate that carbohydrate metabolism by the CF culture was a major source of acetic and propionic acids and that lactic acid was an important metabolic intermediate for the synthesis of the volatile fatty acids.

Animals↗

PubMed1984

Baleen whales: preliminary evidence for forestomach microbial fermentation.

Baleen whales have a multichambered stomach divided into three distinct compartments. The forestomach (first compartment) consists of noncornified and nonglandular tissue and appears to be analogous to the tissue of the rumen. The exact function of the forestomach is unknown; however, we have detected volatile fatty acids in forestomach samples from seven bowhead (Balaena mysticetus) and four gray (Escherichtius robustus) whales. Acetic, propionic, and butyric acids were found in all samples. Seven whale samples also contained valeric, isobutyric, isovaleric, and isocaproic acids. Bacterial counts in 10 of the samples ranged from 5 X 10(8) to 630 X 10(8)/ml of fluid. The types, concentrations, and relative proportions of volatile fatty acids, the presence of significant levels of bacteria, and the morphology of the digestive tract support the hypothesis that a microbial forestomach fermentation occurs in these two species of baleen whales.

Animals↗

PubMed1990

Ecological studies on intestinal microbial flora of Kenyan children with diarrhoea.

The intestinal microflora was analysed together with short-chain fatty acids (SCFA) and bile acids in faeces from nine children with acute diarrhoeal disease in Lari, Kenya. Enteric pathogens such as enteroinvasive E. coli, enteropathogenic E. coli, Yersinia enterocolitica, rotavirus, Giardia lamblia and Entamoeba histolytica were isolated either singly or in combination from diarrhoeal faecal specimens. The most striking finding in these patients was a marked reduction of anaerobes. Analysis of the SCFA revealed a significantly higher quantity of the volatile fatty acids (VFA) such as acetic, propionic, and butyric acid in recovery period faeces in comparison to diarrhoeal faeces, although no significant difference was seen in the quantity of non-volatile fatty acids. On analysing bile acids in faeces, conjugated primary bile acids were detected from all cases in diarrhoea whereas the free form of secondary bile acids was seen only in recovery. The pH of recovery faecal specimens was significantly lower than that in diarrhoeal faecal specimens. There was a parallel between the decrease in number of anaerobes and fluctuation in the amount of SCFA, showing that the drastic reduction of VFA accompanying decrease of anaerobes during the diarrhoeal state, and the rise in pH thought to arise from these facts, result in an increase of water content.

Bacteria↗

PubMed1984

Detection of Clostridium difficile in faeces by direct gas liquid chromatography.

Stool specimens examined for the presence of Clostridium difficile and its cytotoxin were screened by gas liquid chromatography for the presence of volatile fatty acids and p-cresol. Twenty seven of 110 (25%) stools yielded C difficile or cytotoxin; iso-valeric acid was detected in 63/110 (57%) and iso-caproic acid in 18/110 (16%) stools. Para-cresol was found in 24/71 (34%) stools examined. Iso-valeric acid was detected in 85% of stools positive for C difficile, whereas iso-caproic acid (41%) and p-cresol (52%) were found in much lower numbers of C difficile-positive stools. It is concluded that gas chromatographic detection of volatile fatty acids or p-cresol in faeces are not satisfactory screening tests for the presence of C difficile.

Caproates↗

PubMed1976

Effect of certain organic compounds on saliva secretion in sheep.

In two sheep fitted with esophageal cannulas the stimulation of resting saliva secretion by intrabuccal injections of volatile fatty acids (VFA) and of certain organic plant compounds was investigated. Volatile fatty acids, salicin and vanillin increased saliva flow rate by 100, 76 and 72% over 2.5 min after injection. Minor positive or negative effects were obtained with quercitrin, protocatechuic acid, grass juice, anethole and agaricinic acid. Injections of volatile fatty acids and of salicin induced chewing activities, which were significantly correlated with salivary flow rates. The results indicate that organic plant compounds can provide a stimulus for saliva secretion mediated in part by chewing activities.

Animals↗