[Role of volatile fatty acids and pH of the gastrointestinal contents in Shigella infection in starved monkeys (author's transl)].
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Animals↗
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Results for “Fatty Acids, Volatile”
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Relationship between salmonella population and levels of volatile fatty acids in ceca of Eimeria tenella-infected chickens.
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Animals↗
Determination of volatile fatty acids and lactic acid in bovine plasma and ruminal fluid by high performance liquid chromatography.
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Animals↗
Influence of Eimeria tenella infection on the cecal pH, oxidation-reduction potential and concentration of volatile fatty acids in gnotobiotic chicken.
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Animals↗
Inhibition of GH releasing factor (GRF)-induced GH secretion by intraruminal infusion of volatile fatty acids (VFA) in sheep.
A VFA mixture solution containing acetate, propionate and butyrate (the molar ratio of acetate, propionate and n-butyrate = 61.7:24.3:14.0) was infused into the rumen at various rates (53.5, 107 and 214 mumol kg-1 min-1) over 6 h to examine the effects on basal and growth hormone-releasing factor (GRF, 0.25 micrograms kg-1)-induced increase in secretion of GH, insulin, glucagon and somatostatin (SRIF) in five castrated male sheep. Intraruminal infusion of the VFA mixture into the 18-h-fasted animals at the rates of 53.5, 107 and 214 mumol kg-1 min-1 finally raised the total intraruminal VFA concentration from 91.4 to 100.2 (P > 0.05), 175.9 (P < 0.05) and 234.5 (P < 0.05) mmol l-1, respectively. A preliminary experiment showed that an infusion rate of 107 mumol kg-1 min-1 mimics the postprandial increase in ruminal VFA. The basal plasma GH concentrations (2 to 4 h after the start of VFA infusion) and the area under the profiles for GH release in response to the intravenous GRF injection, which was done 4 h after the start of VFA infusion, were significantly decreased by the VFA infusion rates of 107 and 214 mumol kg-1 min-1. Furthermore, the VFA infusion noticeably increased basal plasma concentrations of insulin, but it scarcely changed the basal levels of glucagon, SRIF and glucose. From these results we conclude that an increase in the ruminal VFA concentration, even within the physiological range, would suppress GH secretion from the ovine anterior pituitary, and that the postprandial rise in the ruminal VFA concentration may be one of the factors normally suppressing GH secretion in sheep.
Animals↗
The effects of diet on water flux and volatile fatty acid concentrations in the rumen of growing beef steers fed once daily.
In vivo temporal changes in ruminal liquid flow, liquid volume and VFA concentrations were determined in growing steers following once-daily feeding. Crossbred beef steers (n = 8; 278 +/- 8 kg), used in a crossover design, were trained to consume 180% of their maintenance energy intake within 2 h of either a high-forage (54% hay: 46% concentrate; HF) or high-concentrate (28% hay: 72% concentrate; HC) diet. For each animal on each diet, ruminal VFA concentrations, liquid volumes and liquid dilution rates were determined during a 2-h period before feeding and during three consecutive 2-h periods following feeding. Water was withheld during these periods to observe physiologically rather than behaviorally induced changes. At equal energy intakes, diet alone had no effect on VFA concentrations (P greater than .10), although changes in total VFA, acetic and isobutyric acids differed during the time periods following feeding due to diet (diet x time period interaction; P less than or equal to .10). Ruminal volume and dilution rate were altered in a reciprocal manner due to diet, with greater volumes and lower dilution rates observed in HC than in HF steers. Differences among time periods were observed for dilution rate and propionic acid concentrations. In general, these differences can be explained by comparison of the prefeeding time period with the postfeeding time periods. A numerical, but not statistically significant, increase in ruminal volume was observed following feeding. The effects of diet on volume and liquid dilution rate of the rumen must be considered when assessing total nutrients available for animal absorption.
Analysis of Variance↗
Potential contribution of absorbed volatile fatty acids to whole-animal energy requirement in conscious swine.
Chronic cannulas were placed in the hepatic portal vein, ileal vein, and carotid artery in seven crossbred growing gilts trained to consume once daily 1.2 kg of a 16% CP corn-soybean meal diet. Eleven days after surgery, each pig (37.4 kg BW) was placed in an open-circuit calorimeter and its cannulas were connected to a system for determining portal absorption of nutrients. The whole-animal heat production and net portal absorption of gut VFA were measured simultaneously for 12 h after the pig was fed 1.2 kg of feed. Plasma concentrations of VFA, including acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids, in portal and arterial samples were determined by gas chromatography after a cleanup by ion-exchange chromatography. The net portal absorption of VFA was calculated by multiplying the porto-arterial plasma concentration difference of the VFA by portal vein plasma flow. Plasma flow was estimated by the indicator-dilution technique using p-aminohippuric acid as the indicator. The energy value of absorbed VFA was the sum of products of each individual VFA multiplied by its corresponding value of the heat of combustion. The mean hourly energy value of absorbed VFA during the 12-h postprandial period was .65 +/- .03 kcal.h-1.kg BW-1. The mean hourly whole-animal heat production was 2.70 +/- .04 kcal.h-1.kg BW-1. Thus, in our 37.4-kg pigs, which were trained to consume 1.2 kg of a 16% CP corn-soybean meal diet once daily, the gut VFA absorbed into the portal vein could contribute 23.8 +/- 1.1% to whole-animal heat production if all of the absorbed VFA were combusted to CO2.
Absorption↗
Effect of different volatile fatty acids mixtures on energy metabolism in cattle.
Four Friesian steers (mean BW = 282 kg) were given mixtures of VFA and casein by intragastric infusion to give a total energy input of 675 kJ/kg BW.75. Casein supplied 16.3% of the energy and 777 mg N/kg BW.75. The molar proportion of butyric acid was held constant at 8 mol/100 mol, and the acetic and propionic acids varied inversely. Acetic acid was varied in 12 increments from 11 to 91 mol/100 mol and propionic acid proportion varied inversely. Heat production, blood (urea, insulin, beta-hydroxybutyrate, free fatty acids) and urine metabolites (urea, N, VFA) were measured. There were no differences (P greater than .05) in heat production until the acetic acid proportions exceeded approximately 90 mol/100 mol, at which point there was a decrease in heat production (P less than .05) accompanied by a considerable excretion of acetic acid in the urine. Above 80 mol/100 mol acetic acid, beta-hydroxybutyrate was greatly elevated, accompanied by a small decrease in blood glucose and blood insulin together with an increase in blood free fatty acid concentration. There was also an elevation of N excretion in the urine. When the proportion of propionic acid exceeded 76 mol/100 mol there were some metabolic disturbances resulting in blood hemolysis, an increase in N excretion in the urine, and nervous disposition of the animals. It is concluded that differences in heat production between roughage and concentrate diets are not likely to be a result of differences in the energetic response to different proportions of VFA. Differences in activity during standing, feeding, and ruminating may, therefore, be more important.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The effects of ruminal acidosis on volatile fatty acid absorption and plasma activities of pancreatic enzymes in lambs.
Twenty crossbred wethers (41.9 +/- 4.0 kg BW), each fitted with a ruminal cannula and a jugular catheter, were used in a completely randomized design to examine the effects of ruminal acidosis on plasma activities of pancreatic enzymes and fractional rates of VFA absorption. Lambs had ad libitum access to a 50% concentrate diet. Acidosis was induced by an intraruminal dose of glucose at 0, 6, 12, or 18 g/kg BW via the ruminal cannula. Ruminal fluid and plasma were collected 0, 4, 8, 12, 18, 24, 36, 48, and 72 h after dosing. Ruminal fluid pH was reduced (linear, P < .001) with increasing ruminal glucose. Total ruminal VFA concentration decreased (linear, P < .01) and D(-)-lactate (linear, P < .01) and L(+)- lactate (linear, P = .07) concentrations increased with increasing ruminal glucose. Activities of amylase and lipase in plasma were not affected by ruminal glucose (P > .10). Ten days after the acidosis insult, rumens were evacuated and contents were replaced with an isotonic Cr:VFA solution to measure ruminal VFA absorption. Ruminal fluid was collected hourly from 0 to 6 h. Fractional rate of acetate absorption was 13% lower for lambs receiving 18 g/kg BW glucose than for control lambs. In addition, fractional liquid passage rate was lower (P < .05) in lambs receiving 18 g/kg BW glucose 6 mo after the insult of acidosis. These data suggest that a short-term, severe insult of acute acidosis does not result in pancreatic tissue damage but may result in reduced ruminal VFA absorption for an extended period of time.
Absorption↗
Prediction of ruminal volatile fatty acids and pH within the net carbohydrate and protein system.
A steady-state model of the production, absorption, passage, and concentration of ruminal VFA and pH is developed from published literature data and is structured to use the feed descriptions and inputs from the net carbohydrate and protein system. Included are the effects of pH on growth rate and yield of structural and non-structural carbohydrate-fermenting bacteria; production of acetate, propionate, butyrate, lactate, and methane; conversion of lactate to VFA; ruminal absorption of acids; and prediction of ruminal pH from dietary measures and from ruminal buffering and acidity. The root mean square error of predicted total VFA concentration was 12 mM. Individual VFA fractions were inadequately predicted. In a review of literature data, effective NDF (eNDF) provided a better correlation with ruminal pH than forage or NDF. Digestion rate of NDF remained at normal levels above pH 6.2, which corresponds to a minimum eNDF of 20% of dietary DM. Further research is needed to determine the individual VFA produced from carbohydrate fractions at various pH, the appropriateness of partitioning the starch and pectin carbohydrate pool into slowly and rapidly degraded fractions, and the effect on microbial yield, total tract digestibility, and predicted energy values of feeds.
Acetates↗
Effect of resistant starch on net portal-drained viscera flux of glucose, volatile fatty acids, urea, and ammonia in growing pigs.
Net portal-drained viscera (PDV) flux of glucose, VFA, ammonia, and urea was determined in pigs fed diets with or without resistant starch. Diets consisted of 65% cornstarch (diet CS), 32.5% cornstarch and 32.5% raw potato starch (diet CPS), or 65% raw potato starch (diet PS); the remaining 35% supplied all amino acids, fat, fiber, minerals, and vitamins. The diets contained twice the maintenance requirement for energy and were fed twice daily to four barrows (initial BW 56 kg) in three periods in a crossover design. The pigs were fitted with catheters in a mesenteric vein, a mesenteric-artery, and the portal vein, and net PDV flux was calculated by multiplying portal-arterial concentration differences and corresponding portal vein flow. Net PDV flux of glucose was significantly less after feeding diets CPS and PS, and portal absorption of ileally digested glucose was 89, 66, and 41% for diets CS, CPS, and PS, respectively. Net PDV flux of VFA was lowest after feeding diet CS and three to four times higher after feeding diets CPS and PS. Net PDV flux of ammonia was highest for diet CS and almost halved after feeding diets CPS and PS. There was a small negative net PDV flux of urea for diets CS and CPS, which significantly increased after feeding diet PS. These results suggest that excretion of nitrogen is shifted from urine to feces primarily by reduction of the net PDV flux of ammonia when resistant starch is fed.
Ammonia↗
Neutral detergent fiber disappearance and gas and volatile fatty acid production during the in vitro fermentation of six forages.
Samples of unfractionated forage and isolated NDF from six forages were fermented in vitro, and NDF disappearance and gas and VFA production were measured over time. Rates based on each of these data sets were calculated using a one-pool logistic model. The rates of NDF disappearance and gas and VFA production did not differ within each forage. Gas and VFA production were linearly related to NDF digestion. Gas yield was .35 mL/mg (r2 = .92) of NDF digested for the isolated NDF. The amount of total VFA produced per milligram of NDF digested was more variable than gas (r2 = .72), with a slope of .01 mmol VFA/mg of NDF digested. The relationship between gas and VFA production was linear (mean slope of 1.43 mmol gas/mmol VFA, r2 = .69). The ratios of end products (gas and VFA) to NDF digestion and the ratio of acetate:propionate were variable during the first 8 h of fermentation but changed little after this time. Changes in the acetate: propionate ratio explained 23% of the variation in gas produced per millimole of total VFA detected.
Acetates↗
Glycyl-L-sarcosine absorption across ovine omasal epithelium during coincubation with other peptide substrates and volatile fatty acids.
To define the interactions between the absorption of glycyl-L-sarcosine (Gly-Sar; .1 mM) and glycine, L-methionylglycine, glycyl-L-leucine, L-carnosine, or L-methionylglycyl-L-methionyl-L-methionine (each at 5 mM), ovine omasal epithelium was collected from eight wethers (average BW=69+/-8.2 kg) and mounted in parabiotic chambers. [1,2]-[14C]Glycyl-L-sarcosine was used as a marker to monitor the presence of Gly-Sar. The Gly-Sar concentration in the omasal epithelium after 60 min of incubation was greatest (P < .05; .0055 nmol/mg dry tissue) when only Gly-Sar was present. Glycine inhibited (P < .05) Gly-Sar movement through the tissue by 20%, and peptide substrates inhibited (P < .05) Gly-Sar movement by 60 to 85%. The appearance of Gly-Sar in serosal buffers increased quadratically (P < .001) with time. Numerically, Gly-Sar appearance in serosal buffers was stimulated by the presence of glycine and peptide substrates. In a second experiment, ovine omasal epithelium was collected from four lambs (average BW=47+/-6.0 kg) to determine the interactions of Gly-Sar absorption (.1 mM) alone or when coincubated with either 10 mM butyric acid, or with a mixture of VFA (50 mM acetic acid, 40 mM propionic acid, and 10 mM butyric acid). The movement of Gly-Sar through the omasal epithelium was greatest (P < .05) when only Gly-Sar was present, and the VFA mixture inhibited (P < .05) Gly-Sar movement by 84%. Results from these studies support the idea that peptides can be absorbed across omasal epithelium and that the process involves mediated as well as nonmediated mechanisms, including possibly paracellular transport.
Absorption↗
Net flux of glucose, lactate, volatile fatty acids, and nitrogen metabolites across the portal-drained viscera and liver of pregnant ewes.
Our objective for this study was to determine the pattern of nutrient flux across the portal-drained viscera (PDV) and liver in ewes with varying numbers of fetuses. Catheters were placed in the hepatic portal vein, a branch of the hepatic vein, a mesenteric vein, and the abdominal aorta of ewes. Blood flow and net nutrient release across the PDV and liver were determined before exposure to rams. Ewes were then mated, which resulted in two ewes not pregnant and in six ewes with single and 11 ewes with twin lambs. Additional measurements were taken 103, 82, 61, 39, 19, and 6 d before parturition. Net PDV glucose release did not differ from zero (-.4 +/- 8.4 mmol/h; P = .58). In ewes with singles, premating net hepatic glucose release was 34.4 +/- 2.4 mmol/h, and 19 d before parturition it was 46.2 +/- 3.8 mmol/h. In ewes with twins, premating net hepatic glucose release was 36.8 +/- 2.7 mmol/h, and 19 d before parturition it was 47.4 +/- 2.8 mmol/h. Net PDV lactate release did not differ with litter size (P = .58) or days from parturition (P = .14; 9.7 +/- 4.6 mmol/h). Net lactate uptake by the liver increased in pregnant ewes as the pregnancy progressed (P < .001). The hepatic extraction ratio for lactate increased in late pregnancy (P = .02). Net PDV and hepatic release of acetate and propionate were not different with litter size or days from parturition. Hepatic extraction ratios of VFA did not differ with litter size or day from parturition. The patterns of change in hepatic metabolite fluxes are similar to the patterns of change in gravid uterus metabolite uptake. Hepatic lactate uptake seems to be regulated during pregnancy.
Ammonia↗
The effect of narasin on apparent nitrogen digestibility and large intestine volatile fatty acid concentrations in finishing swine.
The effect of narasin on apparent nitrogen and dry matter digestibilities and large intestine VFA concentrations in finishing swine was investigated. The study used 21 crossbred barrows averaging 72 kg. Seven blocks were formed on the basis of pretreatment dry matter digestibility, and barrows were randomly assigned to three treatments in each block. Treatments consisted of a control (C) and narasin (N15 and N30) applied at 15 and 30 ppm, respectively. Fecal and urine samples were collected. Upon the completion of the digestibility work, intestinal samples were taken from three locations, and VFA concentrations for each animal were measured. Weight gains for the N15 and N30 treatments were increased 3.0 and 6.0% (not significant), respectively, over control. Fecal nitrogen was decreased (P < .05) in the narasin-fed barrows, and apparent nitrogen digestibility was increased (P < .05). Neither nitrogen retention nor urinary nitrogen excretion was altered (P > .05) due to narasin. There were no increases (P > .05) in apparent dry matter digestibility due to narasin. Analysis of pooled colon samples showed an increase (P < .05) in the concentration of propionic acid in relation to acetic and butyric in the narasin-fed barrows. Butyric acid was reduced (P < .05) in the transverse colon of narasin-fed barrows. In summary, narasin administration to finishing barrows resulted in improved apparent nitrogen digestibility, thus decreasing fecal nitrogen, and increased relative concentrations of propionic acid in the large intestine.
Animals↗
Net absorption and hepatic metabolism of glucose, L-lactate, and volatile fatty acids by steers fed diets containing sorghum grain processed as dry-rolled or steam-flaked at different densities.
We determined the effect of processing method (dry-rolled [DR] vs steam-flaked [SF]) and degree of processing (flake density; FD) of SF sorghum grain on splanchnic (gut and liver) metabolism of energy-yielding nutrients by growing steers. Diets contained 77% sorghum grain, either DR or SF, with SF at densities of 437, 360, or 283 g/L (SF34, SF28, or SF22). Eight multicatheterized steers (340 kg initial BW) were used in a randomized complete block design. Net output or uptake of glucose, L-lactate, VFA, and beta-hydroxybutyrate (BHBA) were measured across portal-drained viscera (PDV), liver, and splanchnic (PDV plus liver) tissues. Net absorption of glucose across PDV was negative and similar for all treatments (average of -104 g/d). Decreasing FD of SF sorghum grain linearly increased (P < or = .04) net absorption and splanchnic output of L-lactate by 20 and 130%, respectively, and hepatic synthesis (P = .06) and splanchnic output (P = .01) of glucose by 50%. Reducing FD did not alter output or uptake of acetate or n-butyrate by gut and liver tissues, but linearly decreased (P = .06) splanchnic output of BHBA by 40%. Net absorption (P = .18) and splanchnic output (P = .15) of propionate tended to be increased linearly by 50% with decreasing FD. Neither processing method (SF vs DR) nor degree of processing (varying FD) altered hepatic nutrient extraction ratios or estimated net absorption and splanchnic output of energy. Maximal contribution of propionate, L-lactate, and amino acids (alpha-amino N) to gluconeogenesis averaged 49, 11, and 20%, respectively. Feeding steers SF compared to DR diets did not alter net output or uptake of energy-yielding nutrients across splanchnic tissues, except net absorption of acetate tended to be greater (P = .13) for steers fed DR. Increasing degree of grain processing in the present study, by incrementally decreasing FD, tended to linearly increase the net absorption of glucose precursors (propionate and lactate), resulting in linear increases in synthesis and output of glucose by the liver to extrasplanchnic tissues (e.g., muscle).
3-Hydroxybutyric Acid↗
Volatile fatty acid metabolism by epithelial cells isolated from different areas of the ewe rumen.
Cells were harvested from four rumen locations in four 2- to 3-yr-old ewes fed fescue hay to determine whether cell origin has an effect on cellular VFA metabolism. Tissue (approximately 150 cm2) was excised from the anterior cranial pillar, ventral sac floor, caudal pillar surface, and dorsal sac ceiling. Cells were isolated using serial tryptic digestion. One milliliter of isolate was incubated for 2 h in 6 mL of medium containing 25 mM propionate and 10 mM butyrate. Incubations were terminated at 0, 30, 60, 90, and 120 min and analyzed for beta-hydroxybutyrate, acetoacetate, lactate, and pyruvate. Cell yield was 22, 22, 24, and 14 (+/- 6) x 106 cells/mL, and viability was 92, 92, 94, and 87% for anterior cranial pillar, ventral sac floor, caudal pillar surface, and dorsal sac ceiling, respectively. All metabolite concentrations and ratios of redox pairs increased throughout the incubations, indicating continuous cellular activity. Final 2-h concentrations (nmol/10(6) cells) were 123, 113, 163, and 158 (+/- 35) for beta-hydroxybutyrate; 38, 42, 24, and 45 (+/- 10) for acetoacetate; 25.3, 20.6, 10.1, and 20.4 (+/- 5.6) for lactate; and 2.54, 0.98, 1.06, and 1.31 (+/- 0.61) for pyruvate in the anterior cranial pillar, ventral sac floor, caudal pillar surface and dorsal sac ceiling incubations, respectively. Origin of rumen tissue had no significant effect on metabolite production, indicating that cellular location is not a critical factor that affects rate of rumen epithelial cell VFA metabolism under these specific in vitro conditions.
Animal Feed↗
Effects of volatile fatty acid supply on their absorption and on water kinetics in the rumen of sheep sustained by intragastric infusions.
Three sheep fitted with a ruminal cannula and an abomasal catheter were used to study water kinetics and absorption of VFA infused continuously into the rumen. The effects of changing VFA concentrations in the rumen by shifting VFA infusion rates were investigated in an experiment with a 3 x 3 Latin square design. On experimental days, the animals received the basal infusion rate of VFA (271 mmol/h) during the first 2 h. Each animal then received VFA at a different rate (135, 394, or 511 mmol/h) for the next 7.5 h. Using soluble markers (polyethylene glycol and Cr-EDTA), ruminal volume, liquid outflow, apparent water absorption, and VFA absorption rates were estimated. There were no significant effects of VFA infusion rate on ruminal volume and water kinetics. As the VFA infusion rate was increased, VFA concentration and osmolality in the rumen were increased and pH was decreased. There was a biphasic response of liquid outflow to changes in the total VFA concentration in the rumen, as both variables increased together up to a total VFA concentration of 80.1 mM, whereas, beyond that concentration, liquid outflow remained stable at an average rate of 407 mL/h. There were significant linear (P = 0.003) and quadratic (P = 0.001) effects of VFA infusion rate on the VFA absorption rate, confirming that VFA absorption in the rumen is mainly a concentration-dependent process. The proportion of total VFA supplied that was absorbed in the rumen was 0.845 (0.822, 0.877, and 0.910 for acetate, propionate, and butyrate, respectively). The molar proportions of acetate, propionate, and butyrate absorbed were affected by the level of VFA infusion in the rumen, indicating that this level affected to a different extent the absorption of the different acids.
Animals↗