Autor: Stefan Patrick Stuchlich

Organic trace elements – a review The objective of the present review was to summarize the current state of knowledge on the use of organic trace elements in the livestock feed and to examine in what way organic trace elements based on terms of bioavailability and performance parameters, such as body weight development, retention in tissues and organs, immunity, reproduction and excretion considering the allowance ranges are distinct from conventional mineral trace element compounds. On the one hand, trace elements were examined for their function mechanisms, effect spectra and social significance, and on the other hand, current study results were compared with their effectiveness in consideration of the above reference values. In addition to a brief sketching of the investigated elements copper, selenium, iron, zinc and manganese, the use of these elements in the legal framework as well as national and international supply recommendations were presented as a clear overview of the complex trace elements. Furthermore, in addition to a historical classification, organic trace elements were put into a current context, especially with regard to their production, chemical structure, bioavailability and resorption behavior. In chapter 11 the use of organic trace elements was collected in the current literature and summarized by species. In addition to the performance, the contents of the above five trace elements in excrement, blood and the concentration of these elements in organs and tissues were of particular interest. For the present work a total of 564 studies on organic trace elements in farm animals were evaluated. Taking into account the timeliness (not older than 30 years), the target species (pigs, poultry, cattle), the comparability of the studies (organic and inorganic study group), the trace elements (Zn, Mn, Cu, Fe, Se) and the examination parameters (supply area, bioavailability, immunity, reproduction, environment) remained a total of 173 studies, summarized in Chapter 11. The literature research was carried out on the basis of the Cochrane guidelines and the required literature mostly could be downloaded online as a PDF file. These sources of literature have been incorporated into the literature management program Mendeley, which automatically reads author, year etc. from the files and can create text references by means of a MS Word plug-in. Furthermore, a search for catchwords within the literature selected as described above is possible, whereby cross-connections can be produced better and documented results by several research groups can be demonstrated. The following conclusions were made: • For organic trace elements, a number of positive effects are described which are mostly due to their chemical structure. In connection with this, there is often the indication of improved biological availability. The positive effects are partly due to increased retention in different organs or a more effective transition to offspring, eggs or milk. This can lead to an improved supply of the young animals. • Another point of view is a more effective intermediate utilization, which manifests itself, for example, in an improved activity of different metalloenzymes and has positive influences on immune defense, reproduction, etc. • When the trace element supply was carried out in the lower supply area, the trace elements from the organo compounds were usually more readily available than from mineral sources. The study results show that the use of organic trace element compounds in situations with suboptimal supply can have positive effects on performance parameters. This finding also applies to the incorporation of trace elements into the organs or tissues suitable for the indication. • Through the use of smaller doses of organic trace elements, it is also possible to reduce the amount of trace element supplementation in various cases and thus to considerably reduce the discharge of trace elements via economic fertilizers. • Although usualy the most cost-effective way to provide trace elements is the use of a highly available inorganic source of nutrients, the bioavailability of organic trace elements is often higher, which is why they are increasingly used in recent years. However, it is not completely scientifically determined whether this increase in bioavailability is accompanied by improved efficiency. Depending on species and study design, past studies could show the same, diminished or increased efficiency of organic versus mineral trace elements, with the majority of the investigated organic trace elements having equal efficiency.