1. Institute of Animal Physiology; Physiological Chemistry and Animal Nutrition, Veterinary Faculty; Ludwig- Maximilians University of Munich; Veterinarstrasse 13 D-80539 Munich Germany
2. Institute of Brain Chemistry and Human Nutrition; University of North London; London N7 8DB
3. Erben, Fitz and Partners Veterinary Clinic; Gessertshausen Germany
4. Institute of Zoo Biology and Wildlife Research (IZW); Berlin Germany