New species of rumen treponemes

Three strains of rumen treponemes were isolated and partially characterized. The strains differed significantly one from another in morphology, fermentation characteristics and plasmid profiles. Their genetic variability was assayed using DNA-based molecular approaches. Easily differentiated ARDRA (amplified ribosomal DNA restriction analysis) patterns indicated that the strains represent different bacterial species.     

Pectinolytic enzymes of large rumen treponemes.

Large spiral organisms isolated from the rumen of cattle produced and released into the external environment a complex of pectinolytic enzymes, consisting mainly of poly(1,4-alpha-D-galacturonide) lyase (EC 4.2.2.2, formerly EC 4.2.99.3), most active at pH 8.0 to 9.0, and another enzyme acting at pH below 7.0, probably a poly(1,4-alpha-D-galacturonide) glycanohydrolase (EC 3.2.1.15). The mixture of enzymes degraded polygalacturonate to saturated and unsaturated monogalacturonates as the end products. A pectin pectylhydrolase (pectinesterase) (EC 3.1.1.11) was also present in the clarified cultures.     

Pectinolytic enzymes of large rumen treponemes.

Large spiral organisms isolated from the rumen of cattle produced and released into the external environment a complex of pectinolytic enzymes, consisting mainly of poly(1,4-alpha-D-galacturonide) lyase (EC 4.2.2.2, formerly EC 4.2.99.3), most active at pH 8.0 to 9.0, and another enzyme acting at pH below 7.0, probably a poly(1,4-alpha-D-galacturonide) glycanohydrolase (EC 3.2.1.15). The mixture of enzymes degraded polygalacturonate to saturated and unsaturated monogalacturonates as the end products. A pectin pectylhydrolase (pectinesterase) (EC 3.1.1.11) was also present in the clarified cultures.     

Isolation and characterization of large treponemes from the bovine rumen.

Ten strains of strictly anaerobic spiral organisms were isolated in pure culture from a 10(-7) dilution of bovine rumen contents. Three strains were studied in detail. These strains morphologically resembled previously isolated and described rumen treponemes except the new isolates were larger, 0.7 micrometer wide and 12 to 25 micrometer long. They rapidly fermented pectin and, less readily, L-arabinose, inulin, and sucrose. Acetic and formic acid were the main fermentation products from pectin; small amounts of succinic acid were also formed.     

Staphylococci associated with the rumen of young and wild ruminants

Staphylococcus warneri, Staph, xylosus, Staph. saprophyticus, Staph. epidermidis, Staph. sciuri subsp. lentus, Staph. sciuri subsp. sciuri and Staph. cohnii subsp. urealyticum were the most frequently occurring staphylococci in the rumen content and wall of young and wild ruminants. Staphylococcus warneri formed a high percentage mainly among 2–9-week-old ruminants. Staphylococcus hominis was found only in mouflons. Staphylococcus gallinarum was detected only in calves. Staphylococcus aureus was the predominant representative of coagulase-positive staphylococci in the rumen of wild ruminants. Most of the strains examined could not be identified as known species.     

Influence of diet on the rumen protozoal fauna of indigenous African wild ruminants

A study was carried out to determine if the protozoal fauna of indigenous African wild ruminants was different from that found in their domestic counterparts and if the animal's diet influenced the number and types of protozoa. Samples of rumen contents were collected in 1997 and 2001 from various indigenous African wild ruminants in Kenya. All three ruminant feeding types were sampled: browsers or concentrate selectors (giraffe and Guenther's dik-dik); intermediate or adaptable mixed feeders (impala, Thomson's gazelle, Grant's gazelle and eland); grass or roughage eaters (hartebeest and wildebeest). Total concentration of ciliate protozoa and percentage generic distribution were determined. In general, protozoal concentrations were higher in concentrate selectors, followed by the intermediate or opportunistic mixed feeders and lowest in the grass and roughage eaters. Both Thomson's and Grant's gazelle were protozoa-free in the 2001 samples. Entodinium percentages were considerably higher in concentrate selectors and intermediate mixed feeders, compared to roughage eaters. Two genera of protozoa previously found in only a few African ruminants, Epiplastron and Opisthotrichum, were observed in several additional animal species and represent new host records. A difference was noted in the protozoal species composition of the indigenous wild ruminants from that previously observed in African domestic ruminants.     

Production of indolic compounds by rumen bacteria isolated from grazing ruminants

AIM: To screen rumen bacterial cultures and fresh ruminal isolates for indole and skatole production. METHODS AND RESULTS: Culture collection strains and fresh bacterial isolates from rumen contents of sheep and dairy cows were screened for the production of indolic compounds. Clostridium aminophilum FT, Peptostreptococcus ssp. S1, Fusobacterium necrophorum D4 produced indole and Clostridium sticklandii SR produced indoleacetic acid. Fresh isolates from sheep (TrE9262 and TrE7262) and dairy cows (152R-1a, 152R-1b, 152R-3 and 152R-4) produced indole, indolepropionic acid, tryptophol and skatole from the fermentation of tryptophan and indoleacetic acid. Glucose altered the indolic compounds produced in some, but not all, isolates. TrE7262 and 152R-4 were identified as Clostridium sporogenes and 152R-1b as a new Cl. aminophilum strain. Isolates TrE9262, 152R-1a and 152R-3 were not closely related to any described species but belong to Megasphaera, Prevotella and Actinomyces genera, respectively. CONCLUSIONS: Rumen bacteria that produced a range of indolic compounds were identified. Some isolates are distinct from the previously described bacteria and may represent novel species. SIGNIFICANCE AND IMPACT OF THE STUDY: These observations will contribute to understanding skatole and indole formation in the rumen and will lead to methods that control the formation of indolic compounds in pasture-grazed ruminants.     

微生物介导反刍动物瘤胃氨生成及其对瘤胃功能的影响

反刍动物瘤胃中栖息着丰富多样的微生物,其在瘤胃内氨生成过程中发挥了重要的作用。微生物介导的氨基酸脱氨基作用和非蛋白氮水解作用是瘤胃内氨生成的主要途径。微生物介导了瘤胃内氨的生成,同时瘤胃内产生的氨也会反馈影响微生物菌群结构及瘤胃上皮功能,进而影响瘤胃发酵及宿主健康。本文主要综述了瘤胃微生物在介导氨生成中的作用和氨对瘤胃消化及瘤胃上皮功能的影响,以期对后续研究有所启发。     

Influence of rumen protozoa on methane emission in ruminants: a meta-analysis approach

A meta-analysis was conducted to evaluate the effects of protozoa concentration on methane emission from ruminants. A database was built from 59 publications reporting data from 76 in vivo experiments. The experiments included in the database recorded methane production and rumen protozoa concentration measured on the same groups of animals. Quantitative data such as diet chemical composition, rumen fermentation and microbial parameters, and qualitative information such as methane mitigation strategies were also collected. In the database, 31% of the experiments reported a concomitant reduction of both protozoa concentration and methane emission (g/kg dry matter intake). Nearly all of these experiments tested lipids as methane mitigation strategies. By contrast, 21% of the experiments reported a variation in methane emission without changes in protozoa numbers, indicating that methanogenesis is also regulated by other mechanisms not involving protozoa. Experiments that used chemical compounds as an antimethanogenic treatment belonged to this group. The relationship between methane emission and protozoa concentration was studied with a variance−covariance model, with experiment as a fixed effect. The experiments included in the analysis had a within-experiment variation of protozoa concentration higher than 5.3 log₁₀ cells/ml corresponding to the average s.e.m. of the database for this variable. To detect potential interfering factors for the relationship, the influence of several qualitative and quantitative secondary factors was tested. This meta-analysis showed a significant linear relationship between methane emission and protozoa concentration: methane (g/kg dry matter intake)=−30.7+8.14×protozoa (log₁₀ cells/ml) with 28 experiments (91 treatments), residual mean square error=1.94 and adjusted R²=0.90. The proportion of butyrate in the rumen positively influenced the least square means of this relationship.     

Variability in individual animal's intake of minerals offered free-choice to grazing ruminants

A review of the literature indicates that there is very little published information on the variation in intake of minerals and other supplements offered free-choice to grazing animals. Most of the studies have been conducted with molasses feedblocks and liquid licks and the data indicate large day to day and among animal variation. A computer recording system has been developed and tested which allows for more information to be collected with regard to frequency of consumption of free-choice supplements by grazing animals. Studies have been conducted with molasses blocks and loose mineral supplements provided to grazing cattle. Results indicate that the supplements were consumed by almost all animals on a regular basis. However, there was considerable variation among animals in the quantity of supplement consumed. For the molasses blocks daily intake averaged 1.2 ± 0.6 kg per head within a range of 0.72–1.65 kg. For the mineral supplement the average daily consumption was 135 ± 55 g per head within a range of 50–300 g. The supplement feeders were visited every hour of the day but approximately 40% of the visits occurred in the late evening. Information on the behavioural pattern of consumption may enable strategies to be developed which could reduce the variation in consumption.     

The copper-molybdenum antagonism in ruminants. I. The formation of thiomolybdates in animal rumen

The formation of thiomolybdates, MoO_xS_4?x^2?(x = 0, 1, 2, or 3), from molybdate and sulphide salts in aqueous media has been studied under conditions which simulate the fluid phase in the rumen. The influences of the sulphide:molybdenum ratio, pH and phosphate levels on the nature of the species formed were investigated. The thiomolybdates, in particular the MoS_4^2? ion, have been implicated as the active intermediates in the widespread molybdenum induced copper deficiency that affects ruminants. The results presented here show that, under physiological conditions, di- and trithiomolybdates will form more readily than tetrathiomolybdate.     

Variability of Actinobacteria, a minor component of rumen microflora

Actinobacteria (Actinomycetes) are a significant and interesting group of gram-positive bacteria. They are regular, though infrequent, members of the microbial life in the rumen and represent up to 3 % of total rumen bacteria; there is considerable lack of information about ecology and biology of rumen actinobacteria. During the characterization of variability of rumen treponemas using non-cultivation approach, we also noted the variability of rumen actinobacteria. By using Treponema-specific primers a specific 16S rRNA gene library was prepared from cow and sheep rumen total DNA. About 10 % of recombinant clones contained actinobacteria-like sequences. Phylogenetic analyses of 11 clones obtained showed the high variability of actinobacteria in the ruminant digestive system. While some sequences are nearly identical to known sequences of actinobacteria, we detected completely new clusters of actinobacteria-like sequences, representing probably new, as yet undiscovered, group of rumen Actinobacteria. Further research will be necessary for understanding their nature and functions in the rumen.     

In vitro fibrolytic potential of anaerobic rumen fungi from ruminants and non-ruminant herbivores

In the present study, anaerobic fungi were isolated from different ruminants and non-ruminants; i.e., cattle, buffalo, sheep, goats, wild bluebulls, elephants, deer, and zebras; and were identified as Anaeromyces, Orpinomyces, Caecomyces, Piromyces, and Neocallimastix sp., based on their morphological characteristics. These isolates possessed significant in vitro hydrolytic enzyme activities; however, an isolate of Caecomyces sp. from elephant was found to exhibit maximum activity, i.e., filter paper cellulase (Fpase; 21.4 mIU/ml), carboxymethyl cellulose (CMCase; 15.1 mIU/ml), cellobiase (37.4 mIU/ml), and xylanase (26.0 mIU/ml). Besides, this isolate also showed the significantly highest ability to digest plant cell-wall contents in vitro. The in vitro dry matter digestibility increased from 45.1 to 48.9% after 48 h of incubation, and the plant cell-wall contents, in terms of neutral detergent fiber and acid detergent fiber, decreased from 64.2 to 61.3% and from 31.3 to 29.6%, respectively. These results indicate that such fibrolytic ruminal fungal strains are prevalent in wild herbivores such as elephants, as well as in other ruminants and non-ruminants, and could be exploited as microbial feed additives for improved nutrition and productivity in domesticated ruminants.     

The intraruminal papillation gradient in wild ruminants of different feeding types: Implications for rumen physiology

Browsing and grazing ruminants are thought to differ in the degree their rumen contents are stratified—which may be due to different characteristics of their respective forages, to particular adaptations of the animals, or both. However, this stratification is difficult to measure in live animals. The papillation of the rumen has been suggested as an anatomical proxy for stratification—with even papillation indicating homogenous contents, and uneven papillation (with few and small dorsal and ventral papillae, and prominent papillae in the atrium ruminis) stratified contents. Using the surface enlargement factor (SEF, indicating how basal mucosa surface is increased by papillae) of over 55 ruminant species, we demonstrate that differences between the SEF_dorsal or SEF_ventral and the SEF_atrium are significantly related to the percentage of grass in the natural diet. The more a species is adapted to grass, the more distinct this difference, with extreme grazers having unpapillated dorsal and ventral mucosa. The relative SEF_dorsal as anatomical proxy for stratification, and the difference in particle and fluid retention in the rumen as physiological proxy for stratification, are highly correlated in species (n = 9) for which both kind of data are available. The results support the concept that the stratification of rumen contents varies among ruminants, with more homogenous contents in the more browsing and more stratified contents in the more grazing species. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.