1. Veterinary
Parasitology Group, Department of Veterinary Disease Biology, University of Copenhagen, Dyrlægevej 100, DK-1870 Frederiksberg C, Denmark
2. Chemistry
and Biochemistry Laboratory, School of Agriculture, Policy and Development, University of Reading, Reading RG6 6AT, United Kingdom
3. Animal Nutrition Group, Wageningen University & Research, P.O. Box 338, 6700 AH Wageningen, The Netherlands
4. Section
for Bacteriology, Pathology and Parasitology, National Veterinary
Institute, Technical University of Denmark, Bülowsvej 27, DK-1870 Frederiksberg C, Denmark
5. Norwegian Veterinary Institute, P.O. Box 750 Sentrum, N-0106 Oslo, Norway