Gastrointestinal Physiology Team

Staff

  • Melanie Brede, PhD
  • Dr. rer. nat. Alexandra Muscher-Banse
  • Yvonne Ambrecht, Animal care taker
  • Joie Behrens, Doctoral Student
  • Marion Burmester, VMTA
  • Madeleine Heinzendorff, Trainee animal takecarer
  • Pascal Hoffmann, PhD Student
  • Karin Hustedt, Biology lab technician
  • Nicole Issel, PhD Student
  • Michael Rohde, animal takecarer
  • Nadine Schnepel, BTA
  • Dirk Voigtländer, Biology lab technician
  • Sarah Weber, Doctoral Student
  • Luisa Sophie Zillinger, PhD Student

Research

The ingestion, digestion and absorption of food serves to supply the body with nutrients that drive vital processes in the body as a source of energy and serve as building materials for body substance. Furthermore, the composition of the ingested food influences the intermediary metabolism and hormone balance, as well as the environment via the excretion of metabolic end products.

In our working group “Gastrointestinal Physiology” we deal with the influences of the diet on growth, health and metabolism of animals, the mechanisms of digestion and absorption, as well as the excretion of nutrients and their effects on metabolic processes.

We especially focus on the microbial digestion of food in the forestomach system, the reduction of nitrogen and methane emissions by ruminants as well as the influence of dietary factors (nitrogen, calcium or phosphorus) on the growth of young ruminants.

Main focus

Melanie Brede, PhD

Main focus: Microbial fermentation in the forestomach of ruminants

Ruminants are characterized by a forestomach system, in which plant food can be efficiently degraded with the help of bacteria, protozoa and fungi and thus broken down into substrates usable by the ruminant. The community of microorganisms in the rumen is a highly complex system that is influenced by both diet and genetics of the host animal and is also related to its productivity. Using the so-called Rumen Simulation Technique, an in vitro apparatus for investigations on rumen metabolism, we investigate the influence of different feeds or feed additives on rumen fermentation and the composition of the rumen microbiota. In addition, the effects of different physiological and pathological conditions on classical fermentation parameters and the microbial community are investigated. For this purpose, for example, a model for the generation of subacute ruminal acidosis was established and characterized in the RUSITEC system. Furthermore, we study e.g. approaches to reduce methane emissions and to improve fiber degradation in biogas plants. For detailed analysis of the rumen microbiome and metabolome, we collaborate with research groups with sequencing facilities and with metabolomics facilities.

Link Article TiHo Anzeiger (02/2019): Die klimafreundliche Kuh?

 

Dr. rer. nat. Alexandra Muscher-Banse

Main focus: Effect of nitrogen reduction on vitamin D metabolism in growing goats

Nitrogen (N)-reduced feeding of ruminants is desirable in terms of resource conservation as well as environmental and climate protection. Due to the ruminohepatic cycle, ruminants can adapt metabolism and maintain growth and metabolism in times of reduced N supply. From our own studies on growing goats fed a N-reduced diet, it has been shown that there is a disruption of the somatotropic axis and thus decreased insulin-like growth factor 1 (IGF1) levels. The reason for this disruption is thought to be decreased insulin levels, which inhibit growth hormone receptor expression in the liver. Decreased IGF1 levels modulate, among other things, vitamin D metabolism, in which the central enzyme, 1-α-hydroxylase, is decreased in expression and thus many vitamin D-dependent metabolic processes are inhibited such as intestinal absorption of calcium. The 1-α-hydroxylase ensures the formation of active vitamin D3, calcitriol. Thus, the modulation of calcitriol synthesis in the kidney by an N-reduced diet in growing goats will be characterized. The results of this work will contribute to a better understanding of possible interaction partners as well as their dietary regulability by N in growing ruminants. In addition, these metabolic data will provide information to assess animal health.

Link Article BJN (03/2020): https://pubmed.ncbi.nlm.nih.gov/31775916/

Methods/Equipment

RuSiTec Anlage

Rumen simulation technique (RUSITEC)

The rumen simulation technique (RUSITEC) represents a long-established method for simulating microbial fermentation in the rumen in vitro. For this purpose, the fermenters are filled with liquid and solid rumen contents of ruminants at the beginning of the experiment, supplied daily with an appropriate feed ration and continuously supplied with a buffer mimicking ruminant saliva. Liquid effluent and fermentation gas produced are collected. Using this method, the effects of e.g. different feeds or feed additives on microbial fermentation (determination of short-chain fatty acid concentration by gas chromatography, photometric ammonia-N and lactate determination, production of carbon dioxide and methane) and the microbial community can be examined over several weeks. To study the community of bacteria and archaea in RUSITEC in detail, DNA can be obtained for next-generation sequencing or real-time PCR analyses.

Ussing Kammer Schema

Voltage Clamp Ussing Technique

The absorption of nutrients into the body occurs through complex transport processes in the epithelia of the mucous membranes of the gastrointestinal tract. These transport processes are regulated by various factors such as the composition of the diet, age and hormone status of the animals, but may also be altered by diseases and infections. Since nutrient uptake is a basis of the organism's supply according to its needs, its mechanisms and their regulation are the subject of research. The Ussing chamber, introduced as early as 1951 by USSING and ZERAHN and continuously developed since then, allows functional studies to be performed on intact epithelia (from slaughter and biopsy material, cell cultures) under controlled in vitro conditions over several hours.

Gaschromatograph

Gas Chromatography

A key feature of microbial fermentation processes is the production of short-chain fatty acids. A GC2025 (Shimadzu) is available for the analysis of short-chain fatty acids in rumen or intestinal contents.

Photometer

Photometry

Various photometric protocols are established in the institute, e.g. for the determination of calcium, total protein, urea, lactate, NH3-N, phosphate and of enzyme activities (e.g. alkaline phosphatase, Na+/K+-ATPase).

qPCR

Real-time PCR

The gene expression analysis of the structures involved in nutrient transport (transporters, channels, receptors, intracellular signal cascades,...) is performed by real-time PCR. Among other things, the extent to which the amount of specific gene products can be influenced by different dietary factors at the RNA level is investigated. For this purpose, two chemical methods are available for the quantification of mRNA by real-time PCR: TaqMan probe-based chemistry and SYBR Green dye-based chemistry.

Western Blot

Western Blot

In addition to gene expression, dietary factors can also modulate translational processes such as protein expression. The detection of proteins using specific antibodies as well as their quantification is performed by Western blot analysis or ELISA, among others. Chemiluminescence detection using a ChemiDoc system or a color change can be used to quantify the amount of proteins examined.

 

Immunohistochemische Bild

Immunohistochemistry

Besides the quantification of protein expression, the localization of the investigated proteins in an organ system can be characterized in more detail by immunohistology. Here, detection is also performed by direct binding of specific antibodies to an epitope in a tissue section. Visualization is performed by different detection systems.

Feeding trials

Sheep, goats, pigs or poultry can be kept in the institute's own stables for experimental purposes.