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In: Progress in Research on Energy and Protein Metabolism
In: Progress in Research on Energy and Protein Metabolism
In: Progress in Research on Energy and Protein Metabolism
In: Energy and protein metabolism and nutrition in sustainable animal production
"This book compiles the scientific content of the International Symposium on Energy & Protein Metabolism and Nutrition, in Rostock-Warnemünde 13th-18th September 2003. Specialists from all over the world working in energy and protein metabolism research were assembled to discuss scientific matters of physiology, nutrition, immunology and genetics. All scientific contributions, presented as oral communications or posters, are published in this book. Additionally to these more than 150 articles and 10 review papers, presented by invited speakers, give an overview of the state of the art in special research areas of energy and protein metabolism. The book presents latest results in topics of energy metabolism such as environmental aspects of energy homeostasis, dietary and genetic aspects as well as tissue, organ and whole body energy metabolism and methodology. Furthermore this compilation also gives insight in current affairs of protein research, i.e. protein metabolism and microbiology in the gastro-intestinal tract and requirements and post-absorptive metabolism of amino acids. Apart from these specific questions other topics concerning genes and nutrition or modelling and regulation of energy and protein status were of common interest. The intention of these proceedings is to disseminate latest perceptions of energy and protein research and with this to attempt the connection of areas in animal and human life sciences."
Authors: , , and

Respiration chambers equipped with O2, CO2 and CH4 gas analysers allow the short-term measurement of gas exchange as a prerequisite to study dynamics in energy metabolism of farm animals. Starting from those technical aspects and limitations of dynamic gas exchange recordings, this chapter covers the mathematical evaluation of data obtained from short-term gas exchange measurements, circadian variation of fat and carbohydrate oxidation and the dynamics of methane production in relation to feed intake. The final section of this chapter deals with the identification of specific components of energy expenditure from dynamic records of gas exchange such as the thermic effect of feeding, heat production due to physical activity, basal metabolic rate, resting metabolic rate, and fasting heat production.

In: Indirect calorimetry
In: Book of Abstracts of the 68th Annual Meeting of the European Federation of Animal Science
Authors: and

There is the possibility that the metabolic requirement of indispensable amino acids in monogastric mammals is met not only by the diet but also by amino acids synthesized de novo by the gastrointestinal microflora, which are then absorbed. It is therefore crucial to better understand and quantitate the microbial biosynthesis of amino acids in the gastrointestinal tract and its potential role in providing amino acids to meet amino acid requirement. This paper summarizes the available evidence on a contribution of microbial lysine to the host’s lysine homeostasis, applying isotope tracers in humans, pigs, and rats. Between 2 and 20 % of circulating plasma lysine, urinary lysine and body protein lysine of the host, respectively, is derived from intestinal microbial sources. Factors affecting estimates of net microbial IAA contribution are discussed. It was estimated that the porcine small intestine is responsible for more than 90% of microbial lysine uptake. Microbial amino acid synthesis in the gastrointestinal tract utilizes a mixture of various nitrogen sources, i.e. endogenous amino acids, urea and ammonia. Acetate and CO2 and to a lesser degree propionate derived from microbial carbohydrate fermentation form an active precursor pool of carbon for amino acid synthesis. Certain dietary non-starch polysaccharides and oligosaccharides, poorly digestible by mammalian enzymes can affect the composition and metabolic activity of the intestinal microflora, and are demonstrated to serve as carbon precursors for de novo amino acid synthesis in the intestinal microflora. This opens the possibility of manipulation of the microbial composition, and thus its fermentation products potentially available to the host. The intestine is a highly dynamic tissue of continuous replacement. Due to its direct vicinity to the intestinal flora it controls the effect of intestinal microbes on whole-body physiology. There is evidence that at low dietary protein intakes, or lysine concentrations splanchnic tissues benefit more from microbial amino acid sources than peripheral tissues.

In conclusion, using the 15N labeling paradigm a significant contribution of microbial lysine to the host lysine homeostasis is found. However, to assess net contribution of microbial amino is complicated by the nitrogen and amino acid recycling in the gut and the uncertainty of the precursor pool of absorption. Evidence based on 14C data and digesta exchange experiments supports the view that the de novo indispensable amino acid (i.e. isoleucine, leucine, valine, phenylalanine, lysine) synthesis by the small intestinal microflora represents a net addition to dietary amino acids absorbed from the gut.

In: Progress in Research on Energy and Protein Metabolism
In: Energy and protein metabolism and nutrition in sustainable animal production