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At least 19 recordsLinked to original sources

PubMed1977

[Relationship between the volatile fatty acids (VFA) in the rumen and nitrogen secretion into isolated sheep's rumen].

Two sheep with a ruminal fistula and an isolated small rumen were studied for the secretion of ammonia nitrogen, urea nitrogen, and amino nitrogen into the isolated rumen at different levels of volatile fatty acids (VFA) (50, 133-97, and 97-66 M Mol 1(-1)) in the rumen. The VFA level in the rumen was found to exert a great influence on the quantitative secretion of endogenous nitrogen from the blood through the rumen wall into rumen content. When the VFA level in the rumen was increased by administration of a single dose of acetic, propionic, and butyric acid, the secretion of ammonia nitrogen and amino nitrogen abruptly dropped and the secretion of urea into the isolated rumen slightly increased. The over-all amount of nitrogen (NH3-N + urea-N + amino-N) that had passed into the isolated rumen in the course of an hour showed a highly significant correlation with the passage of nitrogen in the form of ammonia and amino nitrogen and was greatest before the application of VFA to the rumen, i.e. at the level of 50 m mol 1-1. Of the metabolites under study, which were passing to the isolated rumen, amino nitrogen shared the greatest proportion (45.38-46.54%). When the VFA level in the rumen was raised, the proportion of ammonia secreted to the isolated rumen decreased and the proportion of urea in the total amount of nitrogen increased.

Animals↗

PubMedDate not supplied

Rumen motility in experimental acidosis of the rumen in sheep.

In rumen acidosis, induced by infusion of saccharose solution and solutions of different volatile fatty acids and lactic acid into the rumen, and during induced disturbances of acid-base equilibrium in the arterial blood the motility of the dorsal sac of the rumen, the pH of rumen content and the indices of acid-base equilibrium in the arterial blood were investigated. The pH and the indices were determined by the micromethod of Astrup with an Acid-Base-Cart ABC-1 unit. During saccharose-induced acidosis of the rumen the pH of its content was decreased and its motility was strongly inhibited. Acidification of rumen content corresponded to the dissociation constant of a given acid. The motility of the rumen was inhibited most strongly by butyric acid, followed with regard of this effect by acetic acid, propionic acid and lactic acid. It was found that hydrogen ions as well as anions and non-dissociated forms of acids produced in the rumen were responsible for inhibition of this motility and that the rise in the concentration of hydrogen ions in the blood had no inhibitory effect on the motility of the rumen.

Acetates↗

PubMed1976

A rumen linear programming model for evaluation of concepts of rumen microbial function.

A linear programming model provides for analysis of general input-output relationships in the rumen, for evaluation of competitive relationships among rumen microbes, and for computation of optimal relationships in the rumen. Eight rumen microbial groups defined on the bases of substrate specificity, nutrient requirements for growth, fermentation products, and relative metabolic activities comprise the central core of the model. Relative metabolic rates of microbial groups calculated from their cell sized were used as coefficients in the objective function. The model was used to evaluate effects of different amounts of protein from feed and various carbohydrates upon microbial population and fermentation patterns as accommodated by current concepts. During the several solutions of the model, considerable simplification of the rumen microflora occurred. This implies that current data and concepts, and the hypothesis regarding relative metabolic rate, as represented in the model, do not accommodate adequately competitions among the several rumen microbial species and, thus, that additional data and concepts regarding rumen microbial interactions are required. Also evaluated were effects of ingestion of bacteria by protozoa upon over-all rumen function, absolute microbial cell yields, cell yields per mole of adenosine triphosphate, and factors affecting these.

Adenosine Triphosphate↗

PubMedDate not supplied

[The use of ribonucleic acids as markers for the measuring of microbial protein yield in the rumen. 2. The effect of sample treatment, the time of sampling and the composition of the ration on the RNA:N ratio in rumen microbes].

In two experiments the influence of the treatment of samples, the sampling time and the composition of the rations on the RNA: N ratio in the rumen microbes was checked. Experiment I proved that freezing (-21 degrees C), thawing and freeze-drying of isolated bacteria and protozoa from the rumen fluid and from the duodenal content did not result in a change of the RNA content and the RNA-N: total N relation. If, however, the rumen fluid is stored deep-frozen before the isolation of the bacteria the N content in the DM of the bacteria decreases by 17% and that of RNA by 30%. This results in a change of the RNA: N relation of 16%. In conclusion, the bacteria are to be isolated immediately after rumen fluid sampling. Isolated bacteria can be stored deep-frozen before RNA determination and then freeze-dried. Experiment II showed that the RNA content of the rumen protozoa varies according to the period after feeding. The RNA: N relation was 0.50, 0.92, 0.70 and 0.58 on average 0, 3, 6 and 8 h after feeding, in which the 3rd hour after feeding can obviously be considered the time of increased microbial activity. The conclusion from this variation is that more than one isolation of microbes must be carried out in the course of the day in order to achieve representative samples. These statements apply to easily and not easily fermentable protein as N source in the feed. It could also be proved that no essential variation is to be expected in the RNA: N relation in the microbes isolated from the rumen fluid in the range of 8-21% crude protein in the DM of the ration (roughage: concentrate = 55: 45). On average the rumen microbes contained 1.7 g RNA-N/16 g N, essential differences between bacteria and protozoa could not be ascertained. From the slight variation of the RNA-N: N relation in the isolated bacteria from various cows one can conclude that there is no need to isolate the microbes of each individual animal.

Animal Feed↗

PubMed1992

Studies of method of conserving grass herbage and frequency of feeding in cattle. 2. Eating behaviour, rumen motility and rumen fill.

The influence of the method of conserving grass herbage and the frequency of feeding on eating behaviour, rumen motility and rumen fill was studied in growing steers. Silage and hay were offered to twelve rumen-cannulated Friesian steers (average initial live weight (LW) 128 kg) at a restricted level of intake (20 g dry matter (DM)/kg LW) either once or eight times daily. With once daily feeding, the daily intake of hay was consumed in a single large meal which lasted about 2 h, while silage was eaten in many small meals throughout the day. The proportion of the day spent ruminating was higher (0.39) for steers offered hay once daily than for those offered silage (0.28) or hay eight times per day (0.29). There was little effect of conservation method on frequency of rumen contraction, but contractile intensity (integration of frequency and amplitude) increased during the second half of the 24 h feeding cycle in steers offered hay either once daily or eight times daily, while the same effect was only observed when silage was offered once daily. Total daily contractile activity (the integration of the frequency and duration of myoelectric spike bursts) was significantly (P less than 0.05) higher in steers offered hay, compared with silage, once daily. The mean weight of organic matter in the reticulo-rumen of steers offered hay was significantly higher than for silage both with once (1593 v. 1326 g organic matter (OM)/100 kg LW, P less than 0.01) and eight (1367 v. 1160 g OM/100 kg LW, P less than 0.05) times daily feeding. The proportion of the particulate pool which was present as small (less than 1.2 mm) particles was always greater than 0.60.

Animals↗

PubMed1992

Comparative growth rates of various rumen bacteria in clarified rumen fluid from cows and sheep fed different diets.

Pure cultures of strains of different species of rumen bacteria were grown in filter-sterilized rumen fluid supplemented with glucose, bicarbonate, and reducing agent (cysteine and sulfide). Growth rates were determined in a series of experiments. Strains of species most abundant in the rumen grew more rapidly than strains of less abundant bacteria. Ammonia, amino acids, and peptides increased growth rates to some extent, but the greatest stimulatory effect for less abundant bacteria was provided by other factors, present in yeast extract. Factors released from lysates of mixed rumen microbes stimulated growth, but their rate of release was slow. It was concluded that, besides energy and nitrogen sources, growth factors of an as-yet-undetermined nature probably play an important role in determining the predominance of different bacterial species in the rumen.

Animals↗

PubMed1978

[Behavior of the trace elements copper, zinc and manganese in bovine rumen. 1. Trace element content of different fractions of rumen fluid and the effect of copper sulfate administration].

Two adult, rumen-fistulated steers were fed, over four consecutive 3-week periods, Cu-deficient and normal hays with and without copper sulphate supplementation. Their rumen liquor levels of copper, zinc and manganese were determined correspondingly. The rumen liquor samples were split into 3 fractions by way of centrifugation, sodium dodecyl sulphate treatment of the sediment and filtration. The fractionation of the rumen liquor showed copper to be contained mainly in the water-soluble supernatant (68%), whilst zinc and manganese are more strongly linked to the microbial fraction (57 and 46%, resp.). The plant residue did not average but 9, 24 and 22% of copper, zinc and manganese, respectively. Copper sulphate supplementation to normal hay resulted in a significantly increased copper content in the supernatant and in the microbial fraction. At the same time, the zinc and manganese content values in the microbial fraction were found increased. However, the same copper sulphate supplementation to Cu-deficient hay was found to reduce highly significantly the copper level in the microbial fraction. It is supposed that the excessively high molybdenum content of this hay (2.5 ng/kg) has prevented any effect of the copper sulphate supplementation. The positive effects of copper sulphate supplementation on the zinc and manganese levels in the bacterial fraction were maintained even when feeding Cu-deficient hay rich in Mo.

Animal Feed↗

PubMed1978

[Behavior of trace elements copper, zinc and manganese in bovine rumen. 2. Passage rate and course of trace element concentration in rumen as influenced by copper sulfate administration].

In experiments on the distribution of copper, zinc and manganese in fractions of rumen liquor (Wetzel and Menke, 1977 (1)) changes in PEG and in trace element concentration during day-time (between 8 a.m. and 6 p.m.) were measured at 2-hour intervals. Rumen volume was 61 l and passage rate 108 and 128 l/day in the two animals used. Average daily passage was calculated to be 40 mg copper, 98 mg zinc and 371 mg manganese. These values were found to be 11% higher than copper intake and 44 and 68% lower than zinc and manganese intakes, respectively. The differences indicate a remarkable endogenous secretion of copper, and a high absorption of zinc and manganese within the rumen. Concentration (mcg/g dry matter) of copper, zinc and manganese in the bacterial fraction and in total rumen liquor decreased slowly in the first hours after feeding, reaching a minimum after 4 to 6 hours and showed a slight increase thereafter. After addition of copper sulphate the curves mostly became linear. The conclusion is drawn that 1.8 ppm copper in inorganic binding does not lead to changes in trace element concentration to an extent that might be harmful to bacterial fermentation.

Animals↗

PubMed1977

The rumen flagellate Piromonas communis: its life-history and invasion of plant material in the rumen.

The rumen flagellat Piromonas communis is the zoospore of a phycomycete fungus inhabiting the rumen. Zoosporogenesis was stimulated by a dietary component (the inducer), and inhibited by compounds affecting membrane structure and function, but not by inhibitors of protein synthesis. The zoospores showed taxis towards the tissues surrounding the inflorescence of Lolium perenne L. in the rumen, invading principally the stomata and damaged tissues. The zoospores germinated on this substratum and the rhizoids of the developing vegetative stage penetrated the tissue, taking up C14 from labelled plant material, which was incorporated into the fungal cells. The conditions for maximum flagellate production (39 degrees C, pH 6-0 to 7-0, high concentration of CO2, absence of O2) resembled those found in the rumen. The organism was cultured in an undefined medium in vitro in the absence of other flagellates.

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↗

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↗

PubMed1992

[Preparatory feeding of the dry stage cow in regard to nutritional condition and the status of the rumen mucosa and rumen flora at calving].

Excessive fat deposition prior to calving and a negative energy balance post partum predispose the high producing cow for an intensive postpartal lipolysis and for the health problems resulting thereof. It was postulated that a well proliferated ruminal mucosa at the beginning of lactation could improve the energy supply by stabilizing the pH of the rumen content with energy rich feed and by providing a high absorption capacity for volatile fatty acids. Results of earlier experiments dealing with this problem are reviewed. Furthermore there is described a pilot experiment with 9 dry cows, which was directed to stimulate rumen mucosa growth ante partum by a low energy ration (roughage) during the first half of the dry period and a high energy ration during the last 3 to 4 weeks prior to calving, without inducing a fat cow. The ruminal mucosa reacted to that feeding regimen as expected and desired. The body weight of 3 cows in moderate and 4 cows in medium body condition increased by 7.2% or 3% during 8 to 11 or 7 to 9 weeks respectively. One of two fat cows lost 4.9% of her body weight within 8 to 9 weeks while the condition of the second animal remained unchanged. No problems were observed at calving. A further progress is expected by feeding the dry cows in two groups with different rations according to their body condition at the end of lactation. Results of experiments as well as practical experiences show that no more than 8 to 10 days are necessary to adapt the ruminal flora to a mixed ration (roughage + concentrates).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1975

Rumen modeling: rumen input-output balance models.

Two models of rumen fermentative relationships expressed as systems of simultaneous linear equations and based on requirements for maintenance of balances of elementary imput and output and metabolic pathways are presented in matrix format consistent with solution by linear programs. Matrix entries defining the two models were verified carefully based upon a survey of the literature, and conceptual bases of the models were validated by comparisons of model outputs with experimental data not used in model construction. The models then were used to evaluate interactions among feed composition, volatile fatty acid yields and patterns, microbial growth yields and efficiencies, and microbial metabolic pathways.

Amino Acids↗

PubMed1978

[The influence of different straw-based ration type on fermentation and production of volatile fatty acids in the rumen of lactating cows. 3. Rumenal fermentation processes and milk yield criteria after using a low-fiber straw pellet batch as basal ration component and a fully pelleted straw-based ration].

Lactating Black-Pied (DSR) cows were used to study, over a period of 100 days, the influence of different basal ration types (I-treated wheat straw pellets, low-fibre; II- monodiet pellets containing 48% of wheat straw; III = conventional rations based on fresh forage and arable root crops) on the molar fermentation pattern and the daily rate of VFA production and some milk yield criteria. Ration types I and II results in almost equal fermentation patterns of the VFA; as against the conventional ration types (III) a significantly higher molar acetate propertion as well as a highly significantly decreased molar proportion of iso-acids were found. The daily rated of VFA production relativated to energy intake were as follows (in the order of the ration types mentioned): 4.9, 4.2 and 5.0, and 3.3, 2.5 and 3.3 moles per 1,000 anergetic feed equivalents (cattle) after 30 and 100 days of feeding, respectively. In both trials, only about 80% of the relative VFA production of the straw pellet-concentrate (I) and conventional (III) ration types were found when feeding fully pelleted diets (II). On account of the relatively wide variation of the experimental results no statistically secured findings were obtained as to the milk yield criteria, but ration type II produced some 200 and 300 kg milk less thant ration types I and III, respectively, during the 100-day experimental period.

Animal Feed↗

PubMed1976