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PubMed1981

Cellulose fermentation by a rumen anaerobic fungus in both the absence and the presence of rumen methanogens.

The fermentation of cellulose by an ovine rumen anaerobic fungus in the absence and presence of rumen methanogens is described. In the monoculture, moles of product as a percentage of the moles of hexose fermented were: acetate, 72.7; carbon dioxide, 37.6; formate, 83.1; ethanol, 37.4; lactate, 67.0; and hydrogen, 35.3. In the coculture, acetate was the major product (134.7%), and carbon dioxide increased (88.7%). Lactate and ethanol production decreased to 2.9 and 19%, respectively, little formate was detected (1%), and hydrogen did not accumulate. Substantial amounts of methane were produced in the coculture (58.7%). Studies with [2-C]acetate indicated that acetate was not a precursor of methane. The demonstration of cellulose fermentation by a fungus extends the range of known rumen organisms capable of participating in cellulose digestion and provides further support for a role of anaerobic fungi in rumen fiber digestion. The effect of the methanogens on the pattern of fermentation is interpreted as a shift in flow of electrons away from electron sink products to methane via hydrogen. The study provides a new example of intermicrobial hydrogen transfer and the first demonstration of hydrogen formation by a fungus.

Journal Article↗
PubMed1983

Rumen protein degradation and biosynthesis. I. A new method for determination of protein degradation in rumen fluid in vitro.

A method is described for the determination of protein degradation based on measurements of ammonia concentration and gas production (Menke et al. 1979) when a feedingstuff was incubated with rumen fluid in vitro. NH3 liberated during incubation is in part used for microbial protein synthesis. Production of carbon dioxide and methane can be regarded as a measure of energy available for protein synthesis. The ratio, gas production: incorporation of NH3-nitrogen was estimated by addition of starch to the substrate. The response in gas production was linear in the range 0-200 mg starch, when starch was added to 0-200 mg feedingstuff dry matter and 30 ml rumen fluid-medium mixture. Linear regression between NH3-N concentration (y, mg) and gas production (x, ml) yielded an intercept (bo) representing that amount of NH3-N which would be released when no fermentable carbohydrates were available and consequently no bacterial protein synthesis took place. The difference between this intercept bo and NH3-N content in the blank (rumen fluid without substrate added) indicated the amount of NH3 liberated from protein and other N-containing compounds of the feeding-stuff incubated. In vitro-degradable N (IVDN) was calculated as a proportion of total N by the equation: (formula; see text).

Ammonia↗
PubMed1995

Simulation of the effects of diet on the contribution of rumen protozoa to degradation of fibre in the rumen.

A previously described mathematical model, that stimulates the metabolic activities of rumen bacteria and protozoa, was used to examine the contribution of protozoa to neutral-detergent fibre (NDF) degradation in the rumen of cattle. Comparisons between predicted and experimentally observed NDF degradation showed general agreement. Further simulations were performed with diets containing variable proportions of concentrate (between 0 and 1 kg/kg diet DM) and at intake levels ranging between 5.3 and 21.0 kg DM/d. The simulated protozoal contribution to NDF degradation was 17-21% at the lowest intake level. Except for the all-concentrate diets, raising the feed intake level reduced this contribution to 5-13% at the highest intake level. The changes in contribution of protozoa to NDF degradation were related to variations in the fibrolytic bacteria: protozoa value and the NDF-degrading activities of protozoa predicted by the model. In simulations where dietary NDF levels were reduced and starch and sugar levels were increased independently, protozoal contribution to NDF degradation generally increased. These differences were reflected also in the generally increased protozoal contribution to NDF degradation predicted in response to a decreased roughage:concentrate value. The contribution of protozoa also generally declined in response to added N. These changes in predicted protozoal contribution to NDF degradation resulting from dietary variations provided possible explanations for the differences in rumen NDF degradation observed when animals are defaunated.

Animal Feed↗
PubMed2004

Rumen odd and branched chain fatty acids in relation to in vitro rumen volatile fatty acid productions and dietary characteristics of incubated substrates.

A first aim of this batch in vitro experiment (21 h) was to use changes in odd and branched chain fatty acid (OBCFA) patterns to suggest shifts in microbial populations, associated with four types of incubated whole dairy cow diets. Principal component analysis suggested higher dietary starch increased the proportion of C15:0 and C17:0, whereas increased neutral detergent fibre content was positively related to anteiso C15:0 concentrations, which is in agreement with the importance of these fatty acids in respectively amylolytic and cellulolytic bacteria. A second aim of the experiment was to relate rumen volatile fatty acid proportions to OBCFA by principal component regression and to compare these relations with predictions based on diet proximate composition. The R2 values achieved for the regressions between acetate, propionate and butyrate, and OBCFA were 79.6%, 86.6% and 84.9% respectively. Moreover, in the current study, predictions of the rumen fermentation pattern showed higher R2 (p < 0.01) when based on OBCFA compared with proximate feed composition. If relations persist in vivo, there could be scope for milk OBCFA to predict the supply of specific rumen nutrients.

Animal Feed↗
PubMed1986

Rumen ciliate fauna of some Brazilian cattle: occurrence of several ciliates new to the rumen, including the cycloposthid Parentodinium africanum.

Parentodinium africanum was observed in rumen contents of four Brazilian cattle and constituted 4.4, 0.9, less than 0.1, and 10.0% of the total ciliates. This appears to be the first observation of the family Cycloposthiidae in the rumen habitat. Blepharoconus krugerensis, previously observed in the intestines of the elephant, and an unknown species of ciliate with many characteristics similar to the family Paraisotrichidae were each observed in a single animal. A new subspecies, Diplodinium flabellum laterospinatum n. subsp., is also described. Total number of ciliates per ml of rumen contents ranged from 9.0 to 51.2 X 10(4) and included an overall total of 55 species and 4 subspecies.

Animals↗
PubMedDate not supplied

Establishment of a spinated type of Diplodinium rangiferi by transfaunation of the rumen ciliates of Japanese sika deer (Cervus nippon centralis) to the rumen of two Japanese shorthorn calves (Bos taurus taurus).

One liter of rumen fluid containing 4.7 x 10(4) ciliates/ml, representing four genera including nine species of ciliates from a Japanese sika deer was inoculated into two unfaunated Japanese shorthorn calves. Two weeks after inoculation, all species originally present in the inoculum were subsequently detected in the rumen fluid of one or both calves. Ciliate densities ranged from 10(5)-10(6) cells/ml over the remainder of the 33-wk experiment. The inoculum contained Diplodinium rangiferi. which lacks caudal appendages, as is characteristic for the species. However, three weeks later, the rumen fluid of both calves contained D. rangiferi, which possesses caudal appendages varying from a single spine to multiple spines with a complicated furcate appearance. The caudal spines of D. rangiferi did not disappear during the experiment, even when the diet of the calves was switched to the ration of sika deer from which the inoculum was obtained.

Animals↗
PubMed1995

Simple method for cryopreservation of an anaerobic rumen fungus using ethylene glycol and rumen fluid.

The cryopreservation of an anaerobic rumen fungus, Piromyces communis OTS1, was examined at -84 degrees C using dimethyl sulfoxide, propylene glycol or ethylene glycol as cryoprotectants. Ethylene glycol was the most effective agent, combining high survival and low toxicity, followed by dimethyl sulfoxide and propylene glycol. Cell-free rumen fluid in the cryopreservation medium decreased the toxicity of the cryoprotectant agents and also had a protective action per se. A survival of 80% after 1 year storage was obtained when samples with an initial zoospore density of 5 x 10(4) zoospores/ml were equilibrated for 15 min in medium containing 0.64 M ethylene glycol and 5% cell-free rumen fluid, then frozen with dry ice and stored at -84 degrees C.

Animals↗
PubMed1978

Effects of heavy metals and other trace elements on the fermentative activity of the rumen microflora and growth of functionally important rumen bacteria.

The inhibitory effects of high concentrations of essential and non-essential trace elements were tested on the rumen microflora using the rate of fermentation in vitro as the assay. The elements (and the concentration causing 50% inhibition) in decreasing order of toxicity were Hg2+ (20 microgram/ml), Cu2+ (21 microgram/ml), Cr6+ (70 microgram/ml), Se4+ (73 microgram/ml), Ni2+ (160 microgram/ml), Cd2+ (175 microgram/ml), As3+ (304 microgram/ml) and As5+ (1610 microgram/ml). The elements tested that were either weak or noninhibitory at concentrations greater than 400 microgram/ml included Zn2+, Cr2+, Fe2+, Mn2+, Pb2+, and Co2+. Methylmercury was as inhibitory as mercuric chloride to the fermentation. When the inhibitory effect of Cd2+ was tested on separated bacterial and protozoal fractions, it was more inhibitory to the bacteria. The inhibitory effects of trace elements were also determined for a number of axenic cultures of rumen bacteria. The bacteria which most frequently exhibited the greatest sensitivity were Bacteroides succinogenses, Ruminococcus albus, Bacteroides amylophilus, and Eubacterium ruminantium. Those often exhibiting intermediate sensitivities included Butyrivibrio fibrisolvens, Selenomonas ruminantium, and Megasphera elsdenii, while Streptococcus bovis was very refractory to all elements tested. Rumen fluid provided a modest protective effect for the bacteria.

Animals↗
PubMedDate not supplied

Effect of nisin and monensin on rumen fermentation in the artificial rumen.

The objective of this study was to investigate the effect of nisin and monensin on rumen fermentation of diets containing hay and barley (80:20%) in artificial rumen (Rusitec system). The Rusitec system consisted of four fermentation vessels (V1, V2, V3, V4): V1 was without additives (control), V2 received daily 2 mg of nisin, V3 involved 5 mg of monensin and V4 combination of 2 mg of nisin with 5 mg of monensin. After an adaptation period (7 days), the fermentation parameters were determined for six consecutive days. Compared to control diet, the addition of nisin resulted in an increase (P < 0.05) of hemicellulose degradation, acetate, propionate (mmol.day-1) production and energetic efficiency of VFA (E), decrease of butyrate production. Nisin had no effect on dry matter (DM), organic matter (OM), cellulose and detergent fiber degradation, production of total gas, methane and efficiency of microbial synthesis. The addition of monensin resulted in an decrease of DM, OM (P < 0.05), cellulose, hemicellulose, detergent fiber degradation (P < 0.001), total gas, methane and ammonia nitrogen (NH3-N) production. Monensin also significantly decreased acetate, butyrate, L-lactate (mmol.day-1) production and it increased propionate production (P > 0.001) and efficiency of microbial synthesis. The combined effect of nisin and monensin in V4 was similar to the effect of monensin in V3 compared to control. Then, the effect of additive monensin was dominant over nisin. In conclusion, our results indicate that nisin was less effective than monensin on some fermentation parameters (important for the improvement of the efficiency of utilization of the diet by ruminants) in artificial rumen.

Animal Feed↗
PubMed1994

[The effect of cadmium on the protozoan population and rumen fermentation of feed in an artificial rumen].

In our experiment, the effects of 5, 10 and 20 mg cadmium per kg dry matter (DM) on protozoan population and rumen fermentation of feed ration consisting of 11.7 g DM of hay and 2.8 g DM of barley (80: 20%) were followed in artificial rumen (Rusitec). The results of the experiment showed that the addition of 5 and 10 mg cadmium per kg DM less significantly (P < 0.05) decreased the digestibility of DM, organic matter and neutral detergent fibre and significantly (P < 0.01) decreased the digestibility of cellulose of feed ration. It is interesting that the addition of 20 mg cadmium per kg DM did not influence these parameters. Although the total gas production showed a tendency of decrease due to the influence of the addition of 5, 10 and 20 mg cadmium/kg DM, methane and CO2 production was not altered. However, cadmium significantly influenced the production of individual volatile fatty acids-VFA's (mmol/day). The addition of 5, 10 and 20 mg cadmium per kg DM significantly increased acetic acid production (by 10-20%) and decreased propionic acid production (by 18-30%). Therefore, the acetate: propionate ratio was significantly increased (from 1.57 to 2.45-2.60) by the addition of cadmium. The production of n-valeric and iso-valeric acids was also significantly decreased in comparison with the control. The decrease of individual VFA's was more significant at the higher amount of cadmium added into the fermentation system. The proportions of individual VFA's in total VFA production expressed in molar % showed a similar character. The changes in the production of individual VFA's due to the influence of the addition of 5, 10 and 20 mg cadmium per kg DM caused a decrease in energetic efficiency of VFA's (P < 0.001) in comparison with the control. The other parameters of rumen fermentation - utilization of glucose, adenosine triphosphate (ATP) production, fermented hexose, fermented amino acids and fermented organic matter (OMF) were not influenced by the cadmium addition. Although the total microbial matter production in effluent and undigested feed (residues) was significantly (P < 0.001) decreased by the addition of 5, 10 and 20 mg cadmium per kg DM, the efficiency of microbial synthesis expressed as YATP and g microbial N/kg OMF was not changed and achieved the values 11.78-12.68 (YATP), 25.56-28.35 (g microbial N/kg OMF), respectively. The total protozoan population was significantly decreased by the cadmium addition mainly as a result of the decrease of infusoria of Entodinium spp.(ABSTRACT TRUNCATED AT 400 WORDS)

Animal Feed↗
PubMed2006

Klebsiella to Salmonella gene transfer within rumen protozoa: implications for antibiotic resistance and rumen defaunation.

The rumen has long been thought to be a site of gene transfer for microorganisms. Rumen protozoa (RPz) are active predators of bacteria that can harbor antibiotic resistance genes. In this study, RPz were assessed as sites of gene transfer between two bacterial species, Salmonella and Klebsiella. One Klebsiella isolate carried a plasmid bearing bla(CMY-2), encoding an extended-spectrum beta-lactamase conferring ceftriaxone resistance, while the Salmonella was susceptible to ceftriaxone yet capable of thriving within protozoa. In vitro studies revealed that ceftriaxone-resistant Salmonella could be isolated following co-incubation of Salmonella and Klebsiella with RPz obtained from adult cattle and goats. Ceftriaxone-resistant Salmonella were not recovered in the presence of an inhibitor of protozoa engulfment or when a protozoa-sensitive Salmonella was part of the co-incubation. This transfer event was additionally observed in vitro for protozoa-independent stressors although at a significantly lower frequency. The gene transfer event was related to bacterial conjugation since a conjugation inhibitor, nalidixic acid, perturbed the phenomenon. Ceftriaxone-resistant Salmonella were recovered from calves, sheep, and goats co-challenged with ceftriaxone-resistant Klebsiella and ceftriaxone-sensitive Salmonella. However, the transfer event was not observed in calves and sheep that were defaunated prior to the co-challenge. Moreover, Salmonella transconjugants were isolated from separate bovine in vivo studies involving a Klebsiella donor carrying a plasmid conferring colicin activity while no such transconjugants were obtained from defaunated calves. These results provide an important basis for evaluating and preventing the spread of antibiotic resistance and other selective advantages for pathogens present in ruminants.

Animals↗
PubMed1980

[Studies on the effect of phosphoric phenyl ester diamide as inhibitor of the rumen urease of dairy cows. 1. Influence on urea hydrolysis, ammonia release and fermentation in the rumen].

An amount of 0, 0.1, 0.5 and 1.0% (related to N) of phosphoric phenyl ester diamide (PPD) effective as urease blocking substance was applied to the surface of urea with oilbitumen and fed to cows with rumen cannulae over a period of 31 resp. 164 ... 167 days. (The ration essentially consisted of 4.5 kg dried roughage and 1.5 kg starch or 1.1 kg starch plus 0.4 kg sugar and contained 50 g urea). By treating the urea with PPD, the activity of urease, the hydrolysis rate of urea and the NH3-concentration in the rumen were significantly diminished 0.5 to 2 hours after feeding (alpha = 0.05). The effect of PPD was greatest in the first days and decreased with the advancing feeding period. In the variant with 0.5% PPD the examined parameters were significantly reduced after 142 to 164 days, too. This effect remained traceable in its diminished form even after the preparation was discontinued over a period of 35 days. The dynamics of the NH3-concentration was not altered by PPD after a longer feeding period. One can conclude that PPD inhibits the hydrolysis of urea but does not retard it. In conclusion one can say that, because of PPD, the toxicity of urea is lower without the utilisation of urea being better. Due to PPD the molar propionate level in volatile fatty acids decreases significantly and the acetate-propionate relation is expanded.

Ammonia↗
PubMed1999

Morphological and functional development of the rumen in the calf: influence of the time of weaning. 1. Morphological development of rumen mucosa.

The objective of this study was to determine whether the nutritional regimen of rearing calves would influence the morphometric and histological development of rumen mucosa. Twelve male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I), early weaned (6 weeks) group (II) and late weaned (9 weeks) group (III). All animals received additional solid feed. Animals of group I were slaughtered after 6 weeks of age, whereas those in groups II and III were slaughtered after 9 weeks of age. At slaughter, the ruminal digesta amounted to 2035 g (milk group), 3092 g (late weaned group) and 5374 g (early weaned group). The differences in the ruminal molar percentage of SCFA were not significant. There was a trend for lower pH and higher SCFA concentrations in the order late weaned, early weaned and milk fed animals (pH: 6.4, 6.6 and 6.7, respectively; SCFA: 96, 87 and 77 mmol/l, respectively). The mean length (1.07 mm in milk group, 1.45 mm in late weaned group and 1.87 mm in early weaned group), width (0.43, 0.58 and 0.71 mm, respectively) and surface of papillae (190, 232 and 241 mm2/cm2 mucosa, respectively) increased with both the age of the animals and the elevated intake of solid feed, whereas the number of papillae (210, 140 and 92 per cm2 mucosa, respectively) decreased. In both milk-fed groups type A and B corneal cells were present in the Stratum corneum, whereas in the earlier weaned calves type C-cells could be also seen. These findings indicate a more advanced stage of development of the rumen epithelium in the earlier weaned calves fed higher amounts of concentrate and hay.

Animal Feed↗
PubMed1976

Factors affecting the uptake and metabolism of soluble carbohydrates by the rumen ciliate Dasytricha ruminantium isolated from ovine rumen contents by filtration.

A filtration technique is described whereby metabolically-active suspensions of Dasytricha ruminantium can be isolated from rumen contents with negligible contamination by bacteria or other protozoa. The effects of environmental factors and of the diurnal cycle of the rumen on the uptake and metabolism of soluble carbohydrates by these isolated cells were examined. The principal contribution of the protozoan metabolic end-products to the host ruminant is the supply of lactic, acetic and butyric acids during periods when soluble sugars are in excess.

Acetates↗
PubMed1984

Negative correlation between protozoal and bacterial levels in rumen samples and its relation to the determination of dietary effects on the rumen microbial population.

The bacterial protein content and protozoal protein content of unfractionated samples from the liquid-small particle phase of the rumen were determined on the basis of direct microscopic measurement of bacteria numbers and protozoa numbers and cell volumes. Standard values of 8.7 X 10(-11) mg of protein per bacterial cell and 5.9 X 10(-11) mg/micron 3 of protozoa cell volume, obtained from analysis of isolated cells, were used to convert the microscopic measurements to an estimate of the protein content of the rumen sample. When the correlation between bacterial and protozoal protein levels was examined within groups of animals, a highly significant negative correlation between these two parameters was found (P less than 0.001). The variation among animals for total (bacterial plus protozoal) microbial protein was smaller than the variation among animals for bacterial or protozoal protein alone. There was also a highly significant positive correlation (P less than 0.001) between protozoal protein level and total microbial protein level. The variation found among animals in total microbial protein level could be reduced by using a regression equation determined for bacterial versus protozoal protein to correct for the different population dynamics of the two groups.

Animals↗
PubMed1993

Changes in the rumen microbial population and its activities during the refaunation period after the reintroduction of ciliate protozoa into the rumen of defaunated sheep.

Changes in the microbial populations, their activities, and the ruminal fermentation were monitored for 50 d following the reintroduction of ciliate protozoa into four defaunated sheep. A protozoal population was reestablished successfully in each recipient, using a washed inoculum containing approximately 10(3) cells, although there were between-animal differences in the rates of recolonization and genus establishment. Entodinium spp. predominated in the initial stages of the refaunation period and had an apparent maximal generation time of 9-10 h. Bacterial and fungal numbers did not decline following the reintroduction of protozoa and a small transient increase in the numbers of amylolytic and xylanolytic bacteria and fungal zoospores occurred in the early stages of refaunation when the protozoal population was < 10(5)/g ruminal contents, but these subsequently declined as the protozoa established. Although the fibrolytic bacterial population was lowest in period 3 (> 10(5) protozoa/g), the in sacco ruminal digestion of Lolium perenne hay and polysaccharolytic enzyme activities in the solids-associated populations were either maintained or increased when protozoa were present confirming the important contribution of protozoa to fibre breakdown in the rumen. Significant changes in ruminal microbial activities occurred after protozoal reinoculation but before the rumen had refaunated completely. Arylamidase activities in the liquor-phase population and ruminal ammonia concentrations increased significantly within 48 h of transfaunation; the magnitude of the effects became more pronounced as the protozoal population developed. However, volatile fatty acid formation and ruminal pH were not affected after the reintroduction of protozoa.

Aminopeptidases↗
PubMed1981

Degradation of protein by mixed cultures of rumen bacteria: identification of Streptococcus bovis as an actively proteolytic rumen bacterium.

Mixed cultures of rumen bacteria were inoculated into anaerobic buffer solutions containing mixed carbohydrates, casein and ammonia, and rates of bacterial growth, protein degradation, ammonia formation or utilization and lactate production were determined. Bacterial growth rate was varied by the provision of excess carbohydrate (one large dose at the onset of the incubation) or limited carbohydrate (small doses every hour or every 2 hr). When carbohydrate was limited, growth rate was slow, the extent of protein degradation was small and lactate did not accumulate in the fermentation vessels. Lactate production and protein degradation were also negligible during the initial phases of the high carbohydrate, fast growth rate incubations, but large increases in each were seen after 3 hours. Microscopic examination of the fast growth incubations revealed large numbers of small ovoid cells similar to Streptococcus bovis, while tha slow growth incubations exhibited a variety of morophological types and very few small ovoid cells. Because the lactic acid and morphological data suggested that proliferation of S. bovis might be responsible for rapid proteolysis, effects of gram-positive antibiotics were examined. When compared against a fast growth control, both thiopeptin (5 ppm) and monensin (5ppm) were found to decrease protein degradation, but the inhibition by thiopeptin (50%) was greater than that by monensin (13%). The ratios of protein degraded to bacteria protein synthesized were .659, .362 and .628 for the control, thiopeptin and monensin treatments, respectively. Actively proteolytic strains of S. bovis were isolated from fast growth incubations, and subsequent experiments showed that the ratio of protein degraded to bacterial protein synthesized was approximately 1.50. Collectively, the data indicate that S. bovis is a very proteolytic rumen bacterium.

Ammonia↗
PubMed2005

Rumen fermentation and intestinal supply of nutrients in dairy cows fed rumen-protected soy products.

Four multiparous lactating Holstein cows that were fistulated in the rumen and duodenum and that averaged 205 d in milk were used in a 4 x 4 Latin square design to evaluate the practical replacement of solvent-extracted soybean meal (SSBM) with soy protein products of reduced ruminal degradability. On a dry matter (DM) basis, diets contained 15% alfalfa silage, 25% corn silage, 34.3 to 36.9% corn grain, 19.4% soy products, 18.2% crude protein, 25.5% neutral detergent fiber, and 35.3% starch. In the experimental diets, SSBM was replaced with expeller soybean meal (ESBM); heated, xylose-treated soybean meal (NSBM); or whole roasted soybeans (WRSB) to supply 10.2% of the dietary DM. Intakes of DM (mean = 20.4 kg/d), organic matter, and starch were unaffected by the source of soy protein. Similarly, true ruminal fermentation of organic matter and apparent digestion of starch in the rumen and total tract were not altered by treatments. Intake of N ranged from 567 (WRSB) to 622 g/d (ESBM), but differences among soy protein supplements were not significant. Compared with SSBM, the ruminal outflow of nonammonia N was higher for NSBM, tended to be higher for ESBM, and was similar for WRSB. The intestinal supply of nonammonia nonmicrobial N was higher for NSBM and WRSB and tended to be higher for ESBM than for SSBM. However, no differences were detected among treatments when the flow to the duodenum of nonammonia nonmicrobial N was expressed as a percentage of N intake or nonammonia N flow. The ruminal outflow of microbial N, Met, and Lys was not altered by the source of soy protein. Data suggest that partially replacing SSBM with ESBM, NSBM, or WRSB may increase the quantity of feed protein that reaches the small intestines of dairy cows. However, significant improvements in the supply of previously reported limiting amino acids for milk production, particularly of Met, should not be expected.

Amino Acids↗