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Biomedical subjects

J W Czerkawski

Publications and source records attributed to J W Czerkawski.

At least 19 recordsLinked to original sources
PubMed1985

Metabolism of protein supplements studied by the rumen simulation technique (Rusitec).

Long-term experiments were made with the Rumen Simulation Technique (Rusitec) with hay diet and with three different protein supplements (casein, fish meal and soyabean meal). Soyabean meal made the greatest contribution to the output of end-products of fermentation and casein made the smallest contribution. The supplements did not have any marked effect on the metabolism of the basal diet of hay. The experiments showed that rumen microorganisms destroy a large proportion of protein (measured as total alpha-NH2 groups) and that this loss of protein was increased by supplementation with high protein compounds. The degradation of protein in soyabean meal and fish meal appeared to be considerably greater in the model system than the reported results of measurement in vivo and in situ.

Animals↗
PubMed1984

Microbial metabolism of 1,2-propanediol studied by the Rumen Simulation Technique (Rusitec).

A series of experiments with the Rumen Simulation Technique (Rusitec) showed that 1,2-propanediol was metabolized efficiently by rumen micro-organisms and that the main end-products of fermentation were propionic and 2-methylbutyric acids. Propionaldehyde and n-propanol were also formed as intermediate compounds. The effect of the diol on digestion of the basal diet appeared to be small with concentrate, or when the roughage was supplemented with additional nitrogen (urea). The decrease in the output of acetic and butyric acids was consistent with utilization of C2 units for synthesis of 2-methylbutyric acid. The fermentation of 1,2-propanediol resulted in little or no increase in the output of additional microbial matter. The distribution of radioactivity from [1-14C]1,2-propanediol confirmed that propionaldehyde and n-propanol were the primary products of metabolism of the diol and that the end-products were propionic and 2-methylbutyric acids, with very little labelling of microbial matter. Between 2% and 3% of radioactivity was found in gases and surprisingly the specific radioactivity of methane was higher than that of carbon dioxide, particularly during the initial stages of incubation. Possible pathways in the degradation of 1,2-propanediol by rumen micro-organisms are suggested and discussed in relation to similar reactions established in other systems.

Acyl Coenzyme A↗
PubMed1982

Distribution and changes in urease (EC 3.5.1.5) activity in Rumen Simulation Technique (Rusitec).

1. The Rumen Simulation Technique (Rusitec) was used in a series of long-term experiments to study the distribution and changes of urease (EC 3.5.1.5) activity in a heterogeneous fermentation system. 2. It was shown that in Rusitec the high urease activity from the inoculum decreased to low values, that the rate of decrease was consistent with simple dilution of ureolytic micro-organisms and that the urease activity could be restored to original values by infusion of urea into the reaction vessels. The magnitude of this urease activity was a direct function of the amounts of urea infused. Single daily additions of the same or greater amounts of urea in food or as solid failed to increase the urease activity significantly. 3. In general, urease activity increased 2-6 h after feeding and the increases were greater with roughage diets. 4. The ureolytic activity per unit volume was always higher in compartment 2(space occupied by micro-organisms that are loosely associated with the solid) than in compartment 1 (strained rumen contents) or compartment 3 (space occupied by microbial population that cannot be washed out of the solid matrix). 5. The distribution of urease activity between the compartments was different from the distribution of certain other enzymes (e.g. protease and alkaline phosphatase (EC 3.1.3.1)). 6. Apart from the boundary region, the concentrations of urease, ammonia and volatile fatty acids in compartment 2 were constant, while the concentrations of protein, DNA and another enzyme (alkaline phosphatase) increased with the depth of the compartment. Specific urease activity (per unit weight of protein or DNA) was much higher in compartment 1 than in compartment 2 and it decreased markedly with depth of compartment. 7. The concentrations of ammonia were always much higher in the solid matrix (compartments 2 and 3) than in the free suspension of micro-organisms (compartment 1). There was a linear relation between these two quantities. 8. The results are discussed in relation to published work on the entry and metabolism of urea in the rumen.

Alkaline Phosphatase↗
PubMed1981

Effect of monensin on the fermentation of basal rations in the Rumen Simulation Technique (Rusitec).

1. A long-term experiment was made with the Rumen Simulation Technique (Rusitec), in which the fermentation of a mixed ration of hay (10 g/d) and bruised barley (5 g/d) was compared with the fermentation of the same diet in the presence of 2, 10 and 50 mg monensin/d. 2. Monensin depressed the production of acetic and butyric acids, markedly increased the production of propionic acid and virtually, eliminated the production of isovaleric acid. The production of methane was decreased in the presence of monensin, but this decrease could be accounted for entirely by the changes in the production of volatile fatty acids and redistribution of metabolic hydrogen. 3. The digestibility of dry matter (DM) in the rations declined in the presence of monensin. Determinations of the rates of digestion showed that the digestion of the readily-fermented food in the initial stages was not affected by monensin, but that at 24 h digestion had been inhibited by monensin. The inhibition was due entirely to its effect on the digestion of the fibrous components. Digestion of non-fibrous material was not affected. 4. The efficiency of microbial growth, expressed as g dry weight/mol ATP formed (YATP) and in terms of DM digested, tended to be increased by monensin. This however occurred only at high, non-practical doses. 5. Urease (EC 3. 5. 1. 5) was induced by the addition of urea of the fermentation, but monensin had no effect on urease activity. Although monensin increased the activity of protease in washed suspensions, more food protein apparently escaped degradation. This may have been due to decreased deaminative activity. 6. Monensin altered the microscopic appearance of the fermentation fluid, and changed the activity of some enzymes in sonicated extracts, including alkaline phosphatase (EC 3. 1. 3. 1), acetate kinase (EC 2. 7. 2. 1) and succinate dehydrogenase (EC 1. 3. 99. 1). These results are discussed in terms of known sensitivities of rumen microbes to monensin and their contribution to the fermentation as a whole.

Animal Feed↗
PubMed1980

A novel estimate of the magnitude of heat produced in the rumen.

Using a well-known equation relating the heat production to the respiratory measurements, the total heat produced in the animal is partitioned into heat produced in the rumen and heat produced in the body. It is shown that the values of the partition constants can be calculated by making two simple logical deductions. Consideration of known heats of fermentation of carbohydrate and protein shows that the deductions are justified.

Animals↗
PubMed1979

Experiments with the long-term rumen simulation technique (Rusitec); response to supplementation of basal rations.

1. It is shown that a basal roughage diet can be successfully supplemented with glucose, as long as nitrogen is not limiting. Lack of N depresses the digestibility of the basal ration, results in incomplete fermentation and the increased recoveries of N are consistent with fixation of atmospheric N2. 2. Using a complex, but soluble supplement (whey powder) it is shown that reproducible incremental measurements can be made and that the supplement used gives increases in production of characteristic end-products only (carbon dioxide, methane, acetic and butyric acids). 3. The location of the solid dietary components within the reaction vessel is not important and it is possible to measure changes in a particular component in the presence of others. It is shown that there is sequestration of bacteria and protozoa on the solid digesta.

Ammonium Chloride↗
PubMed1979

Experiments with the longterm rumen simulation technique (Rusitec); use of soluble food and an inert solid matrix.

1. The role of soluble nutrients and of the solid matrix in rumen fermentation was investigated in some detail, and experiments designed to explore the possibility of using a balanced soluble diet and an inert solid matrix, are described. 2. The use of a balanced soluble substrate as the only source of nutrients in the presence of an inert solid phase in the reaction vessels results in vigorous fermentation but is accompanied by disappearance of protozoa from the effluent. 3. In the absence of digestible solid phase, the rate of fermentation and the fermentation pattern depends mainly on the amount and type of nutrients supplied and to a smaller extent on the dilution rate, the variations being greatest at low dilution rates. 4. The solid matrix in the form of wood shavings or the residue remaining after prolonged digestion of hay could sequestrate micro-organisms and could be used as solid phase, but the defined mixture of soluble substrates used resulted in somewhat abnormal fermentation compared with fermentation obtained with solid food. 5. When the solid food included some hay extract and when the dilution rate was not too great a reduced output of protozoa could be maintained. At high dilution rate the outflow of protozoa was negligible and yet considerable numbers of protozoa were found in the solid matrix and associated liquid. 6. A three-compartment model was developed to describe the flow of liquid and microbial matter within the simplified system.

Animal Feed↗
PubMed1977

Design and development of a long-term rumen simulation technique (Rusitec).

1. The paper describes the development and construction of an apparatus for maintaining a normal microbial population of the rumen under strictly controlled conditions over long periods of time. 2. The apparatus is simple to construct and operate. It is possible to do four replicate experiments at the same time. 3. The results of three experiments are given. The experiments showed that when the steady-state was reached it could be maintained indefinitely, with the type and quantities of products of fermentation very similar to those in the rumen of donor animals, including the maintenance of normal protozoal populations for up to 49 d. 4. It was found that within wide ranges, the digestibility of rations and the output of products were independent of dilution rate. 5. Except for the lowest 'level of feeding', the digestibility was independent of the level of feeding. The output of products was proportional to the amount of food digested and was the same as would be expected in sheep on similar rations. 6. An experiment in which a ration of hay was changed to a mainly concentrate ration showed that the fermentation characteristics were determined mainly by the food given.

Animal Feed↗
PubMed1976

The use of pivalic acid as a reference substance in measurements of production of volatile fatty acids by rumen micro-organisms in vitro.

1. A procedure is described for using pivalic acid as an inert reference substance in determination of changes in concentrations of volatile fatty acids (VFA). 2. Pivalic acid in concentrations of up to 80 mmol/1 had no effect on production of methane or VFA by rumen contents. 3. Pivalic acid was inert during incubation with rumen contents from sheep given different diets and with samples taken at different times with respect to feeding.

Acetates↗
PubMed1975

Changes in the rumen metabolism of sheep given increasing amounts of linseed oil in their diet.

1. Linseed oil was incorporated gradually into the diet of four sheep until the animals received 90 g additional fat/d. Attempts were made to measure changes in concentration of substances and rates of synthesis in the rumen directly, and by incubation of rumen contents in vitro (zero-time technique). 2. The high-fat diet increased the dilution rate and the volume of rumen contents and decreased the synthesis of diaminopimelic acid in the rumen. The number of protozoa decreased and the number of bacteria increased in the rumen of animals receiving the high-fat diet. 3. The concentration of volatile fatty acids (VFA) in the rumen decreased for sheep given the high-fat diet, but the capacity of rumen contents to produce VFA in vitro increased. 4. The incorporation of radioactivity from [14C]acetate into lipids during incubation of rumen contents vitro increased with the amount of linseed oil in the diet. The greatest proportional increase was with the bacterial fraction of rumen contents. 5. In the group of four animals used, one animal showed consistent differences in the magnitude of the measured varibles. This animal appeared to have a smaller rumen, a lower dilution rate and larger concentrations of some substances in the rumen. A higher proportion of fatty acids appeared to be synthsized by the micro-organisms from this animal.

Animal Nutritional Physiological Phenomena↗
PubMed1975

New inhibitors of methane production by rumen micro-organisms. Development and testing of inhibitors in vitro.

1. A procedure is described for assaying in vitro the activity of various inhibitors of methane production by rumen micro-organisms. 2. Methods of preparation of various inhibitors are described together with attempts to characterize these compounds by determining their physical properties (physical state, density, chromatographic behaviour), their hydrolysis by rumen contents and their relative potency as inhibitors. 3. The results of preliminary studies with trichloroethanol and its ester with pivalic acid are given. 4. The inhibitory activities of several groups of related compounds are reported. These include the polyhalogenated alcohols and their esters with pivalic acid, the esters of trihalogenated alcohols and monobasic fatty acids from C2 and C16 and the trihalogenated alcohol esters of dibasic acids. The results of experiments with esters of alcohols and polyhalogenated carboxylic and sulphonic acids are also given. 5. It is concluded that the mechanism of action of the inhibitors might be similar to that of known polyhalogenated methane analogues (e.g. chloroform). The relative activity of various compounds might be partly governed by the ease of their absorption into the microbial cells and by the extent to which the esters can be hydrolysed by rumen contents. 6. The results show that some substances are very poor inhibitors, unless they are esterified (e.g. trichloroacetic acid) but on the whole the esters in which the polyhalogen grouping is on the alcohol portion of the molecule are better inhibitors than those in which it is on the acid portion of the molecule.

Animals↗