The digestion of pasture plants by sheep. I. Ruminal production of volatile fatty acids by sheep offered diets of ryegrass and forage oats

1968 ◽  
Vol 19 (3) ◽  
pp. 419 ◽  
Author(s):  
RH Weston ◽  
JP Hogan
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Crude Protein ◽  
Volatile Fatty Acids ◽  
Alimentary Tract ◽  
Soluble Carbohydrate ◽  
Wide Range ◽  
The Mean ◽  
Ad Libitum Intake ◽  
Pasture Plants

The production of volatile fatty acids (VFA) in the rumen of sheep was estimated by isotope dilution techniques. The 12 diets used consisted of dried ryegrass and forage oats and covered a wide range of levels of cell wall constituents (46–40% of the organic matter), crude protein (6–32%), and soluble carbohydrate (5–18%). Each diet was offered at a level equal to approximately 90% of the sheep's ad libitum intake. The production of VFA was correlated with the total amount of organic matter digested in the alimentary tract (r = 0.93–0.95). The mean VFA production per 100 g of organic matter digested in the alimentary tract was equivalent to 56.8 g, 243 kcal, or 0.85 mole. Values for individual diets varied about these means with a coefficient of variation of 6–7%. Rates of VFA production in, and VFA absorption from the rumen were correlated with VFA concentration in rumen liquor (r = 0.67, r = 0.67) and the rumen VFA pool (r = 0.81, r = 0.79). Approximately 76% of the VFA produced in the rumen was absorbed from the rumen, 19% was absorbed from the omasum and abomasum, and 5% passed from the abomasum to the intestines.

The digestion of pasture plants by sheep. III. The digestion of forage oats varying in maturity and in the content of protein and soluble carbohydrate

1969 ◽  
Vol 20 (2) ◽  
pp. 347 ◽  
Author(s):  
JP Hogan ◽  
RH Weston
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Cell Wall ◽  
Organic Matter ◽  
Volatile Fatty Acids ◽  
Fertilizer Application ◽  
Feed Consumption ◽  
Soluble Carbohydrate ◽  
Fertilizer Treatment ◽  
Soluble Nitrogen

A comparison has been made of the composition, intake, and digestion of forage oats grown with and without the application of nitrogen fertilizer and harvested at three stages of maturity. The chemical composition of the forages showed the usual changes with maturity. Fertilizer application had little effect on the levels of cell wall constituents but, as expected, decreased the levels of soluble carbohydrate and increased those of total nitrogen, alcohol-soluble nitrogen, and nitrate. The digestibility of organic matter, cell wall constituents, and nitrogen declined with advancing maturity, all three parameters being little affected by the fertilizer treatment. Feed consumption declined only with the most mature diet and was not affected by the fertilizer treatment even though the high nitrogen (HN) diets supplied 4–5 g nitrate nitrogen per day and relatively small amounts of soluble carbohydrate. There was a loss of dietary nitrogen from the stomach with the HN diets and a gain with the low nitrogen (LN). The amount of nitrogen in the digesta leaving the stomach per unit intake of nitrogen increased with maturity. The quantities of protein leaving the stomach were too great to be accounted for as microbial protein, and hence appreciable quantities of plant protein must have passed through the stomach. The digestibility of crude protein in the intestines was not affected either by maturity of the forages or by fertilizer treatment. There was little effect of advancing maturity or fertilizer application on: (a) the extent of digestion of organic matter and the structural carbohydrates in the stomach relative to that occurring in the intestines; (b) the proportion of digestible organic matter derived from rumen volatile fatty acids and amino acids; � the potential value of the metabolizable energy from volatile fatty acids and amino acids to provide net energy for fattening; (d) most parameters associated with the movement of digesta through the stomach. Advancing maturity of the diets was associated with increased expenditure of time in chewing activities.

The digestion of pasture plants by sheep. IV*. The digestion of Phalaris tuberosa at different stages of maturity

1969 ◽  
Vol 20 (5) ◽  
pp. 925 ◽  
Author(s):  
JP Hogan ◽  
RH Weston ◽  
JR Lindsay
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Organic Matter ◽  
Plasma Levels ◽  
Crude Protein ◽  
Volatile Fatty Acids ◽  
Essential Amino Acids ◽  
Digestible Organic Matter ◽  
Time And Energy ◽  
Dietary Origin

A study was made of the composition, intake, and digestion of dried Phalaris tuberosa forage that had been harvested at three stages of maturity. Advancing maturity was associated with: (i) decreased food intake; (ii) increased expenditure of time and energy in chewing activities; (iii) decline in the rate of flow of digesta from the abomasum though not from the rumen; (iv) decline in digestibility in the whole tract of organic matter, nitrogen, and the structural carbohydrates; (v) decline in the digestion of fibre in the rumen relative to that occurring in the whole tract; (vi) decline in the quantities of volatile fatty acids and amino acids made available to the animal. By contrast only small differences attributable to maturity were observed in: (i) the distribution of digestion of organic matter between stomach and intestines; (ii) the digestibility of nitrogen other than ammonia in the intestines; (iii) the proportions of digestible organic matter derived from volatile fatty acids and amino acids; (iv) the proportions of individual amino acids in the digesta passing to the intestine. It was calculated that microbial piotcin contributed 33, 38, and 47% of the protein passing from the stomach to the intestincs with the diets of advancing maturity. Most of the remaining protein was presumably of dietary origin. About 80% of the crude protein in the digesta was present in the form of amino acids, and the quantities of amino acids released in the intestines were calculated to be equivalent to 64–66 g/100 g crude protein intake. With advancing maturity of the diets the plasma levels of the essential ammo acids except lysine, histidine, and arginine declined; there was little effect of diet on the plasma levels 01 non-essential amino acids. However, relative to total essential amino acids, the ratios of valine and leucine decreased with advancing maturity of the diet while those of lysine, histidine, glutamate, glycine, alanine, and serine increased. * Part 111, Aust. J. Agric. Res., 1969, 20, 347.

Factors limiting the intake of feed by sheep. IV. The intake and digestion of mature ryegrass

1968 ◽  
Vol 19 (4) ◽  
pp. 567 ◽  
Author(s):  
RH Weston ◽  
JP Hogan
Keyword(s):  
Organic Matter ◽  
Feed Intake ◽  
Crude Protein ◽  
Alimentary Tract ◽  
Apparent Digestibility ◽  
Additional Protein ◽  
Ryegrass Hay ◽  
Ad Libitum ◽  
Ad Libitum Intake ◽  
Daily Gain

Intake and digestion studies were conducted with sheep fed on ryegrass hay containing 6% crude protein and having an organic matter digestibility of 58%. The intake of ryegrass was little affected when additional protein was provided both as a dietary supplement and as an infusion per abomasum. When supplements containing adequate amounts of protein and minerals were given, the intake of the hay was still comparatively low at 780 g organic matter per day. Grinding and pelleting the diet of hay + supplements permitted a higher feed intake. It was concluded that feed intake was limited by the resistance of the organic matter of the hay to removal from the rumen. Digestion studies were conducted at a level of feeding equal to approximately 90% of the ad libitum intake. The quantity of organic matter apparently digested in the stomach was equal to 60% of the organic matter digested in the alimentary tract; about 80% of the digestion of fibre took place in the stomach. There was a net daily gain of 7.5 g of nitrogen during the passage of digesta through the stomach, and part of this gain appeared to be due to the passage of endogenous nitrogen into the rumen. The apparent digestibility in the intestines of nitrogen that left the stomach in digesta was 73%; 1.6 g of nitrogen was apparently digested in the intestines per 100 g organic matter intake. Values of certain parameters relating to the movement of digesta through the stomach were similar to those previously recorded with a low quality cereal hay.

The digestion of two diets of differing protein content but with similar capacities to sustain wool growth

1967 ◽  
Vol 18 (6) ◽  
pp. 973 ◽  
Author(s):  
JP Hogan ◽  
RH Weston
Keyword(s):  
Organic Matter ◽  
Protein Content ◽  
Dietary Protein ◽  
Protein Intake ◽  
Crude Protein ◽  
Alimentary Tract ◽  
Soluble Carbohydrate ◽  
Cellulose Digestion ◽  
Low Protein ◽  
Wool Growth

Measurements were made of the digestion in sheep of two diets of differing protein content but known to support similar levels of wool growth. When offered to the sheep at 500 g/day, the high protein (HP) diet provided 13.8 g nitrogen (N), while the low protein (LP) diet provided 5.5 g. With the HP diet, approximately 8.8 g N in forms other than ammonia passed daily through the pylorus; 6.8 g of this N was apparently digested in the intestines. The corresponding values for the LP diet were 8.1 and 6.2. The similarity in wool growth recorded with these diets, despite large differences in dietary protein intake, is consistent with the hypothesis that wool growth is limited by the quantity of amino acid N absorbed from the alimentary tract. The stomach was the site of 72–73 % of the organic matter digestion and more than 90% of the cellulose digestion that occurred in the whole alimentary tract. In addition, approximately 90% of the dietary soluble carbohydrate was apparently digested in the stomach. It was calculated, by making several assumptions, that the quantity of microbial crude protein synthesized in the rumen did not exceed 44–49 g/day, equivalent to 15–16 g/100 g organic matter digested in the rumen. The implications of this calculation in the protein nutrition of ruminants are discussed. The retention time of a soluble marker in the rumen was 15–18 hr, and rates of flow of digesta from the rumen and abomasum were comparatively low.

scholarly journals Impact of Organic Loading Rate in Volatile Fatty Acids Production and Population Dynamics Using Microalgae Biomass as Substrate

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jose Antonio Magdalena ◽  
Silvia Greses ◽  
Cristina González-Fernández
Keyword(s):  
Fatty Acids ◽  
Population Dynamics ◽  
Organic Matter ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Building Blocks ◽  
Biofuel Production ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Wide Range

AbstractVolatile fatty acids (VFAs) are regarded as building blocks with a wide range of applications, including biofuel production. The traditional anaerobic digestion used for biogas production can be alternatively employed for VFAs production. The present study aimed at maximizing VFAs productions from Chlorella vulgaris through anaerobic digestion by assessing the effect of stepwise organic loading rates (OLR) increases (3, 6, 9, 12 and 15 g COD L−1 d−1). The biological system was proven to be robust as organic matter conversion efficiency into VFAs increased from 0.30 ± 0.02 COD-VFAs/CODin at 3 g COD L−1 d−1 to 0.37 ± 0.02 COD-VFAs/CODin at 12 g COD L−1d−1. Even though, the hydrolytic step was similar for all studied scenario sCOD/tCOD = 0.52–0.58), the highest OLR (15 g COD L−1 d−1) did not show any further increase in VFAs conversion (0.29 ± 0.01 COD-VFAs/CODin). This fact suggested acidogenesis inhibition at 15 g COD L−1d−1. Butyric (23–32%), acetic (19–26%) and propionic acids (11–17%) were the most abundant bioproducts. Population dynamics analysis revealed microbial specialization, with a high presence of Firmicutes followed by Bacteroidetes. In addition, this investigation showed the microbial adaptation of Euryarchaeota species at the highest OLR (15 g COD L−1d−1), evidencing one of the main challenges in VFAs production (out-competition of archaea community to avoid product consumption). Stepwise OLR increase can be regarded as a tool to promote VFAs productions. However, acidogenic inhibition was reported at the highest OLR instead of the traditional hydrolytic barriers. The operational conditions imposed together with the high VFAs and ammonium concentrations might have affected the system yields. The relative abundance of Firmicutes (74%) and Bacteroidetes (20%), as main phyla, together with the reduction of Euryarchaeota phylum (0.5%) were found the best combination to promote organic matter conversion into VFAs.

scholarly journals Comparison and evaluation of mechanistic rumen models

1997 ◽  
Vol 78 (4) ◽  
pp. 563-581 ◽  
Author(s):  
A. Bannink ◽  
H. De Visser ◽  
A. M. Van Vuuren
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Dairy Cows ◽  
Volatile Fatty Acids ◽  
Microbial Metabolism ◽  
Nutrient Flows ◽  
Lactating Dairy Cows ◽  
Wide Range ◽  
Physical And Chemical ◽  
Microbial N

Mechanistic rumen models of Baldwin (1995), Danfæer (1990) and Dijkstra et al. (1992) were compared on identical inputs that were derived from trials with lactating dairy cows fed on grass herbage. Consistent differences were detected between models and between predicted and observed outputs. None of the models seemed to predict all nutrient flows best. The models particularly differed in the representation of microbial metabolism: degradation of insoluble substrate, fermentation of substrate into volatile fatty acids, and incorporation of substrate into microbial matter. Differences amongst models in the prediction of these processes compensated for each other and consequently all models predicted the duodenal flow of non-NH3 N, microbial N and organic matter reasonably well. Large differences remained in the prediction of individual nutrient flows, however, and it was stressed that in order to enhance prediction of the profile of nutrient flows, the mechanisms of microbial metabolism need to be tested on their ability to describe the intraruminal transactions. However, this requires more-detailed information on individual nutrient flows and on the microbial or non-microbial origin of duodenal contents. Parameter inputs for physical and chemical feed properties were identified that are improperly defined in extant models or susceptible to error. The description of these feed characteristics needs to be developed further and become identifiable for a wide range of dietary conditions.

Nutritional studies with sheep fed conserved ryegrass. 2. Silage supplemented with dried grass or barley

1980 ◽  
Vol 94 (1) ◽  
pp. 219-227 ◽  
Author(s):  
C. G. Wernli ◽  
R. J. Wilkins
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Energy Demand ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Nitrogen Retention ◽  
High Rate ◽  
Physical Factors ◽  
Digestible Organic Matter ◽  
Nutritional Studies

SummaryGrass silage (21.0 % D.M.) was given ad libitum to sheep together with supplements of rolled barley, dried-grass pellets or dried-grass wafers at 12 and 25 g organic matter (OM)/kg0·75.Intake of silage was greater with supplement at 12 g/kg0·75 but total intake of OM and digestible organic matter (DOM) increased with increasing supplement. Intake of OM was higher with the pellet supplement than with other supplements. Intake of DOM, however, did not differ between the pellet and barley treatments, but was lower with wafers.Concentrations of ammonia and total volatile fatty acids and the molar proportions of butyric and higher volatile fatty acids were higher when silage was supplemented with barley than with dried grass. Mean rumen retention times of silage and of supplement were highest in the barley-supplemented treatments. Dried-grass wafers were retained longer than dried-grass pellets. Supplement treatments did not differ significantly for eating and ruminating times, rumen fluid volume and pH, digestion rate in the rumen and nitrogen retention.At the low supplement rate silage consumption may have been controlled by factors associated directly with the silage, whereas at the high rate intake was limited either by physical factors or by the potential energy demand of the animals.

Volatile fatty acids and sulfide in pressure mains

1995 ◽  
Vol 31 (7) ◽  
pp. 169-179 ◽  
Author(s):  
T. Hvitved-Jacobsen ◽  
K. Raunkjær ◽  
P. H. Nielsen
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Production Rate ◽  
Volatile Fatty Acids ◽  
Production Rates ◽  
Net Production ◽  
Toc Removal ◽  
Sulfide Production ◽  
Transformation Of Organic Matter ◽  
High Sulfide

The main objective was to study the anaerobic transformation of organic matter and sulfide production during wastewater transportation. Emphasis was on the transformation of easily biodegradable organic matter in terms of volatile fatty acids (VFA). Samples from two intercepting pressure mains located in the Northern part of Jutland, Denmark, were taken. The concentration of VFA in the wastewater varied considerably during day and night, being typically between 5 and 50 g/m3. A net production as well as a net removal of VFA was seen during transportation in the pressure mains probably depending on the quality and quantity of the organic matter. Typically 85% of the VFA was acetate and 10% propionate; the remainder was formate, n-butyrate and iso-butyrate. Observed sulfide production rates from the sewer biofilms were typically 0.05 and 0.005 g S/m2 h at 12 and 4 °C, respectively. A high sulfide production rate corresponded with a high VFA concentration. TOC removal was observed in the pressure mains.

Rumen volatile fatty acids on six pasture species and relations with digestibility, voluntary intake and chemical composition

1974 ◽  
Vol 14 (67) ◽  
pp. 161 ◽  
Author(s):  
PJ Michell
Keyword(s):  
Fatty Acids ◽  
Lolium Perenne ◽  
White Clover ◽  
Volatile Fatty Acids ◽  
Total Concentration ◽  
Dactylis Glomerata ◽  
Single Species ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Seasonal Differences

The total concentration and the relative proportions of the volatile fatty acids (VFA) were measured in rumens of sheep fed 78 single species pasture samples. The pastures consisted of regrowths of white clover (Trifolium repens cv. Grasslands Huia), Manawa regrass (Lolium perenne x multiflorum cv. Grasslands Manawa), Ariki ryegrass (Lolium (multiflorum x perenne) x L. perenne cv. Grasslands Ariki), perennial ryegrass (Lolium perenne cv. Tasmania No. 1) , Currie cocksfoot (Dactylis glomerata cv. Currie) and Apanui cocksfoot (Dactylis glomerata cv. Grasslands Apanui), cut eight times between May, 1969 and August, 1970. Sheep fed cocksfoot had lower VFA concentrations, higher proportions of acetate (HAc) and lower proportions of butyrate (HBu) than sheep fed white clover and ryegrass (P < 0.05). They also had lower proportions of propionate (HPr) than sheep fed ryegrass (P < 0.05). Sheep fed white clover had higher proportions of valerate (HVa) than those fed the grasses (P < 0.05). There were no significant (P < 0.05) seasonal differences in total VFA concentration but HAc was lowest with spring pasture (P < 0.05) and HBu was lowest with autumn pasture (P < 0.05). Total VFA concentration was positively related to digestibility (DMD) (r = +0.52, P < 0.01) but species differences occurred and at similar DMD, white clover produced higher concentrations than ryegrass (P < 0.05) which produced higher concentrations than cocksfoot (P < 0.01). The overall relation between total VFA and intake (DMI) was weak but seasonal differences occurred and at similar levels of DMI, winter pasture produced higher VFA concentrations than spring-summer pasture (P < 0.01). The proportion of HPr was positively related to VFA concentration (r = +0.53, P < 0.01) and to water soluble carbohydrate (WSC) content (r = +0.51, P < 0.01) and relations with DMD and DM1 were weak and non-significant (P > 0.05).

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