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Michael K. Theodorou

Bio: Michael K. Theodorou is an academic researcher from Aberystwyth University. The author has contributed to research in topics: Rumen & Neocallimastix. The author has an hindex of 43, co-authored 98 publications receiving 6893 citations. Previous affiliations of Michael K. Theodorou include Rowett Research Institute & Harper Adams University.


Papers
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Journal ArticleDOI
TL;DR: Results obtained establish the pressure transducer as a suitable tool for determining the fermentation kinetics of ruminant feeds and ranking them with respect to their in vitro fermentability.

1,524 citations

Journal ArticleDOI
TL;DR: The Reading Pressure Technique (RPT) as discussed by the authors is a semi-automated gas production technique based on a pressure transducer interfaced with a PC that allows accumulated head-space gas pressure values to be directly entered into a spreadsheet.

524 citations

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TL;DR: A kinetic derivation of this model is offered and it is demonstrated how its parameters can be used to calculate the extent of degradation in the rumen to lend support to the theory that fibrolytic rumen bacteria degrade by erosion and rumen fungi degrade by invasion.

383 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the potential of using perennial ryegrass with a high concentration of watersoluble carbohydrate (WSC) to increase the efficiency of milk production.
Abstract: Eight multiparous Holstein‐Friesian dairy cows in late lactation were used to investigate the potential of using perennial ryegrass with a high concentration of watersoluble carbohydrate (WSC) to increase the efficiency of milk production. After a pretreatment period on a common pasture, the cows were each given ad libitum access to one of two varieties of zero-grazed grass continuously for 3 weeks. Treatments were: high sugar (HS), an experimental perennial ryegrass variety bred to contain high concentrations of WSC; or control, a standard variety of perennial ryegrass (cv. AberElan) containing typical concentrations of WSC. The two grass varieties were matched in terms of heading date. All animals also received 4 kg day ‐1 standard dairy concentrate. Grass dry matter (DM) intake was not significantly different between treatments (11AE6 vs. 10AE7 kg DM day ‐1 ; s.e.d. 0AE95 for HS and control diets respectively), although DM digestibility was higher on the HS diet (0AE71 vs. 0AE64 g g ‐1 DM; s.e.d. 0AE23; P <0 AE01) leading to higher digestible DM intakes for that diet. Milk yield from animals offered the HS diet was higher (15AE3 vs. 12AE6 kg day ‐1 ; s.e.d. 0AE87; P <0 AE05) and, although milk constituent concentrations were unaffected by treatment, milk protein yields were significantly increased on the HS diet. The partitioning of feed N was significantly affected by diet, with more N from the HS diet being used for milk production (0AE30 vs. 0AE23 g milk N g ‐1 feed N; s.e.d. 0AE012; P <0 AE01) and less being excreted in urine (0AE25 vs. 0AE35; s.e.d. 0AE020; P <0 AE01). In a separate experiment, using the same grasses harvested earlier in the season, the fractional rate of DM degradation, measured by in situ and gas production techniques, was higher for the HS grass than for the control. It is concluded that increased digestible DM intakes of the HS grass led to increased milk yields, whereas increased efficiency of utilization of the HS grass in the rumen resulted in the more efficient use of feed N for milk production and reduced N excretion.

375 citations

Journal ArticleDOI
TL;DR: This review highlights some of the many factors that are likely to influence the degree of pollution by their effect on both the vertical and horizontal transport of microorganisms through soil.

319 citations


Cited by
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Journal ArticleDOI
TL;DR: It is shown that a major factor is the total amount of fat and that phospholipid, where 18:2n-6 is located, declines as a proportion of muscle lipid and the proportion of neutral lipid, with its higher content of saturated and monounsaturated fatty acids, increases.

2,116 citations

Journal ArticleDOI
TL;DR: This review presents an overview of the dynamically developing field of mass spectrometry-based metabolomics, a technique that analyzes all detectable analytes in a given sample with subsequent classification of samples and identification of differentially expressed metabolites, which define the sample classes.
Abstract: This review presents an overview of the dynamically developing field of mass spectrometry-based metabolomics. Metabolomics aims at the comprehensive and quantitative analysis of wide arrays of metabolites in biological samples. These numerous analytes have very diverse physico-chemical properties and occur at different abundance levels. Consequently, comprehensive metabolomics investigations are primarily a challenge for analytical chemistry and specifically mass spectrometry has vast potential as a tool for this type of investigation. Metabolomics require special approaches for sample preparation, separation, and mass spectrometric analysis. Current examples of those approaches are described in this review. It primarily focuses on metabolic fingerprinting, a technique that analyzes all detectable analytes in a given sample with subsequent classification of samples and identification of differentially expressed metabolites, which define the sample classes. To perform this complex task, data analysis tools, metabolite libraries, and databases are required. Therefore, recent advances in metabolomics bioinformatics are also discussed.

1,954 citations

Journal ArticleDOI
TL;DR: This paper surveys the development ofMOEAs primarily during the last eight years and covers algorithmic frameworks such as decomposition-based MOEAs (MOEA/Ds), memetic MOEas, coevolutionary MOE As, selection and offspring reproduction operators, MOE as with specific search methods, MOeAs for multimodal problems, constraint handling and MOE
Abstract: A multiobjective optimization problem involves several conflicting objectives and has a set of Pareto optimal solutions. By evolving a population of solutions, multiobjective evolutionary algorithms (MOEAs) are able to approximate the Pareto optimal set in a single run. MOEAs have attracted a lot of research effort during the last 20 years, and they are still one of the hottest research areas in the field of evolutionary computation. This paper surveys the development of MOEAs primarily during the last eight years. It covers algorithmic frameworks such as decomposition-based MOEAs (MOEA/Ds), memetic MOEAs, coevolutionary MOEAs, selection and offspring reproduction operators, MOEAs with specific search methods, MOEAs for multimodal problems, constraint handling and MOEAs, computationally expensive multiobjective optimization problems (MOPs), dynamic MOPs, noisy MOPs, combinatorial and discrete MOPs, benchmark problems, performance indicators, and applications. In addition, some future research issues are also presented.

1,842 citations

Journal ArticleDOI
TL;DR: The adaptation strategies of the extremophilic xylanases isolated to date and the potential industrial applications of these enzymes will also be presented.
Abstract: Xylanases are hydrolytic enzymes which randomly cleave the β 1,4 backbone of the complex plant cell wall polysaccharide xylan. Diverse forms of these enzymes exist, displaying varying folds, mechanisms of action, substrate specificities, hydrolytic activities (yields, rates and products) and physicochemical characteristics. Research has mainly focused on only two of the xylanase containing glycoside hydrolase families, namely families 10 and 11, yet enzymes with xylanase activity belonging to families 5, 7, 8 and 43 have also been identified and studied, albeit to a lesser extent. Driven by industrial demands for enzymes that can operate under process conditions, a number of extremophilic xylanases have been isolated, in particular those from thermophiles, alkaliphiles and acidiphiles, while little attention has been paid to cold-adapted xylanases. Here, the diverse physicochemical and functional characteristics, as well as the folds and mechanisms of action of all six xylanase containing families will be discussed. The adaptation strategies of the extremophilic xylanases isolated to date and the potential industrial applications of these enzymes will also be presented.

1,584 citations

Journal ArticleDOI
TL;DR: Results obtained establish the pressure transducer as a suitable tool for determining the fermentation kinetics of ruminant feeds and ranking them with respect to their in vitro fermentability.

1,524 citations