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Mode of action of feed additives

Trace elements

Trace elements are essential for growth and health. The adequate supply in feed is ensured by additional supplementation of respective trace element salts. However, there are products, in which trace elements are bound in organisc substances that may lead to a better bioavailability for the animal. The Institute of Animal Nutrition investigates these products regarding their effects on growth, health or milk production/quality. Trace elements may also be used as nutritional factors, such as zinc or copper.

Phytogenic substances

Herbs and essential oils are interesting feed additives that may be beneficial for growth and health of animals. Due to the complex composition of these products the related research is also a complex process, involving physiological, immunological and microbiological studies to elucidate their effects.


Microbial enzymes

Microbial enzymes used as feed additives are mainly phytases and xylanases or beta-Glucanases. They are often supplemented to feed for pigs and poultry. The Institute of Animal Nutrition carries out studies on their efficiacacy and mode of action with a range of analytical methods to investigate their effect on animal physiology, -microbiota and –immunology.



These enzymes lead to a better digestibility of plant feeds, as they release bound phytic phosphorus and thus reduce the entry of phosphorus into the environment. Work on phytases include characterization of new (bacterial, modified) phytases regarding their biochemical characteristics, stability in feed and in the digestive tract and this their suitability as feed additive.


Xylanases and beta-glucanases

These enzymes effect a partial degradation of carbohydrates that cannot be digested by the animal. Especially young animals like piglets and chicks are disposed to digestive disturbances when cereals like rye or barley as well as wheat with higher amounts of soluble carbohydrates are fed. The main beneficial effect of xylanases and beta-glucanases is the elimination of intestinal viscosity that interferes with digestive processes. The Institute of Animal Nutrition has been investigating different commercial enzyme products regarding their efficiacy in the animal.