[Observations on the apparent digestibility of copper, iron, zinc and magnesium in dogs]

Investigations on the precaecal and postileal apparent digestibility (net absorption) of trace elements (copper, zinc, iron, manganese) were performed in ileumfistulated and intact dogs (4 each). The animals were fed 3 different protein sources (greaves, soy protein, corn gluten), either isolatedly (except corn gluten) only with mineral and vitamin supplement or as a part of a complete diet (55% of the respective protein source plus rice, cellulose, soy oil and vitaminated mineral supplement). Precaecal and total apparent digestibility of trace elements were evaluated by the marker method (chromium oxide). 1. Copper was mainly net absorbed in the small intestine, with the other elements absorption and secretion in the small and large intestine was seen. 2. The variation of the protein supply in the own experiments did not influence the net absorption of trace elements. 3. Own results and data from the literature show a depression of Zn- and Fe-absorption with diets containing low digestible carbohydrates or crude fibre, in part there may be considerable net losses of trace elements under these conditions. With regard to the feeding practice a suboptimal trace element status of the animal may result not only from low intake but also from an impaired net absorption in the intestinal tract, especially concerning zinc from diets containing low digestible carbohydrates.